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Sector Guidance Note IPPC S6.13
www.environment-agency.gov.uk
General Guidance for the Dairy and Milk Processing Sector
Commissioning Organisation
Environment Agency Rio House Waterside Drive Aztec West Almondsbury Bristol BS32 4UD Tel 01454 624400 Fax 01454 624409 © Environment Agency First Published 2001 ISBN 0 11 3101740 This document is Environment Agency copyright . We specifically allow the following: • Internal business or personal use. You may use this document for your own private use or for use within your business without restriction. • Giving copies to others. You may do this without restriction provided that you make no charge. If you wish to use this document in any way other than as set out above including in particular for commercial gain, for example by way of rental, licence, sale or providing services you should contact: Liz Freenland Data and Information Exploitation Manager Environment Agency Rio House Waterside Drive Aztec West Almondsbury Bristol BS32 4UD
This is an uncontrolled document. To ensure you are using the latest version please check on any of the websites listed within the references. Table 0.1: Record of changes
Version
Date
Issue 1
October 2003
Change
Template Version V5
Written comments or suggested improvements should be sent to Mark Maleham at the Environment Agency by email at
[email protected] or at: Environmental Protection National Service Environment Agency Block 1 Government Buildings Burghill Road Westbury-on-Trym Bristol. BS10 6BF Telephone 0117 914 2868
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Executive summary
This guidance has been produced by the Environment Agency for England and Wales with the Scottish Environment Protection Agency (SEPA) and the Northern Ireland Environment and Heritage Service (EHS). Together these are referred to as “the Regulator” throughout this document. Its publication follows consultation with industry, government departments and non-governmental organisations. What is IPPC
Integrated Pollution Prevention and Control (IPPC) is a regulatory system that employs an integrated approach to control the environmental impacts of certain industrial activities. It involves determining the appropriate controls for industry to protect the environment through a single Permitting process. To gain a Permit, Operators will have to show that they have systematically developed proposals to apply the Best Available Techniques (BAT) and meet certain other requirements, taking account of relevant local factors.
This Guidance and the BREF
This UK Guidance for delivering the PPC (IPPC) Regulations in this sector is based on the BAT Reference document BREF (see Ref. 1) produced by the European Commission. The BREF is the result of an exchange of information between member states and industry. The quality, comprehensiveness and usefulness of the BREF is acknowledged. This guidance is designed to complement the BREF and is cross-referenced to it throughout. It takes into account the information contained in the BREF and lays down the indicative standards and expectations in the UK (England and Wales, Scotland and Northern Ireland). The reader is advised to have access to the BREF.
The aims of this Guidance
The aims of this Guidance are to: •
provide a clear structure and methodology for Operators to follow to ensure they address all aspects of the PPC Regulations and other relevant Regulations
•
minimise the effort by both Operator and Regulator in the permitting of an installation by expressing the BAT techniques as clear indicative standards
•
improve the consistency of Applications by ensuring that all relevant issues are addressed
•
increase the transparency and consistency of regulation by having a structure in which the Operator's response to each issue, and any departures from the standards, can be seen clearly and which enables Applications to be compared
To assist Operators in making applications, separate, horizontal guidance is available on a range of topics such as waste minimisation, monitoring, calculating stack heights and so on. Most of this guidance is available free through the Environment Agency, SEPA or EHS (Northern Ireland) websites (see References) key environmental issues
The key environmental issues for this sector are: •
Water use
•
Effluent management
•
Waste handling
•
Accident risk
•
Hygiene
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Contents 1 Introduction ..............................................................................................1 1.1 Understanding IPPC .............................................................................................2 1.2 Making an application ...........................................................................................5 1.3 Installations covered .............................................................................................6 1.4 Timescales ............................................................................................................7 1.4.1 Permit review periods ............................................................................................ 7 1.4.2 Upgrading timescales for existing plant ................................................................. 7
1.5 Key issues .............................................................................................................9 1.6 Summary of releases ..........................................................................................11 1.7 Technical overview ..............................................................................................12 1.8 Economics ...........................................................................................................13 1.8.1 Sector costs ........................................................................................................ 14
2 Techniques for pollution control ..........................................................16 2.1 The main activities and abatement .....................................................................17 2.1.1 In-process controls .............................................................................................. 17 2.1.2 Materials handling, unpacking, storage ............................................................... 20 2.1.3 Pasteurisation, Sterilisation and UHT .................................................................. 21 2.1.4 Evaporation ......................................................................................................... 22 2.1.5 Drying .................................................................................................................. 23 2.1.6 Centrifugation and Bactofugation ........................................................................ 25 2.1.7 Membrane Separation ......................................................................................... 26 2.1.8 Ion Exchange ...................................................................................................... 27 2.1.9 Filtration .............................................................................................................. 28 2.1.10 Churning ............................................................................................................ 29 2.1.11 Cooling and Chilling .......................................................................................... 30 2.1.12 Freezing and Blast Cooling ............................................................................... 31 2.1.13 Mixing, Blending and Homogenisation .............................................................. 32 2.1.14 Filling ................................................................................................................. 34 2.1.15 Fermentation/Incubation Process ..................................................................... 35 2.1.16 Cleaning and sanitation ..................................................................................... 36
2.2 Abatement of point source emissions .................................................................41 2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6
Abatement of point source emissions to air ........................................................ 41 Abatement of point source emissions to surface water and sewer ..................... 46 Abatement of point source emissions to groundwater ........................................ 61 Control of fugitive emissions to air ...................................................................... 62 Control of fugitive emissions to surface water, sewer and groundwater ............. 65 Odour .................................................................................................................. 67
2.3 Management techniques .....................................................................................69 2.4 Raw materials .....................................................................................................72 2.4.1 Raw materials selection ...................................................................................... 72 2.4.2 Waste minimisation ............................................................................................. 74 2.4.3 Water use ............................................................................................................ 77
2.5 Waste handling ...................................................................................................82 2.6 Waste recovery or disposal .................................................................................83 2.7 Energy .................................................................................................................85 2.7.1 Basic energy requirements (1) ............................................................................ 86 2.7.2 Basic energy requirements (2) ............................................................................ 87 2.7.3 Further energy-efficiency requirements ............................................................... 89
2.8 Accidents .............................................................................................................90 2.9 Noise ...................................................................................................................94 2.10 Monitoring .........................................................................................................96 2.10.1 Emissions monitoring ........................................................................................ 96 2.10.2 Environmental monitoring (beyond installation) ................................................ 99
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2.10.3 Monitoring of process variables ...................................................................... 100 2.10.4 Monitoring standards (Standard Reference Methods) .................................... 101
2.11 Closure ............................................................................................................103 2.12 Installation issues ............................................................................................105
3 Emission benchmarks .........................................................................106 3.1 Emissions inventory ..........................................................................................106 3.2 Emission benchmarks .......................................................................................108 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6
Emissions to air associated with the use of BAT ............................................... 108 Emissions to water associated with the use of BAT .......................................... 109 Standards and obligations ................................................................................. 109 Units for benchmarks and setting limits in permits ............................................ 110 Statistical basis for benchmarks and limits in permits ....................................... 111 Reference conditions for releases to air ............................................................ 111
3.3 Biochemical oxygen demand ............................................................................112 3.4 Chemical oxygen demand .................................................................................114 3.5 Halogens ...........................................................................................................115 3.6 Heavy metals ....................................................................................................116 3.7 Nitrogen oxides .................................................................................................117 3.8 Nutrients (phosphates and nitrates) ..................................................................118 3.9 Particulate and suspended solids .....................................................................120 3.10 Sulphur dioxide ...............................................................................................121 3.11 Volatile organic compounds ............................................................................122
4 Impact ..................................................................................................123 4.1 Impact assessment ...........................................................................................123 4.2 Waste Management Licensing Regulations .....................................................125 4.3 The Habitats Regulations ..................................................................................126 References ...............................................................................................................127 Abbreviations ...........................................................................................................130 Appendix 1: Some common monitoring and sampling methods .............................131 Appendix 2: Equivalent legislation in Scotland & Northern Ireland .........................135 Appendix 3: Groundwater Regulations 1998 Sechdule of listed substances and recommendations for List I (DEFRA) .......................................................................137
List of figures Figure 1.1: Overview of the activities within the milk processing sector ............................................. 12 Figure 2.1: Cleaning-in-place chemical recovery membrane system ................................................. 76 Figure 2.2: Example of four-stage counter-flow system based on pea cannery ................................. 81
List of tables Table 1.1: Specific timescale improvements ......................................................................................... 8 Table 2.1: Process monitoring and control equipment ........................................................................ 19 Table 2.2: Abatement options for specified pollutants ........................................................................ 44 Table 2.3: Abatement options information .......................................................................................... 45 Table 2.4: Water treatment for the Food and Drink sector .................................................................. 57 Table 2.5: Summary of aerobic and anaerobic treatment processes ................................................. 58 Table 2.6: Membrane bio reator (MBR) - activated sludge (AS) comparison ..................................... 60 Table 2.7: Raw material substitutions ................................................................................................. 74 Table 2.8: Potential use for waste ....................................................................................................... 84 Table 2.9: Example breakdown of delivered and primary energy consumption ................................. 86 Table 2.10: Example format for energy efficiency plan ....................................................................... 88 Table 2.11: Monitoring of process effluents released to watercourses ............................................... 97 Table 2.12: Monitoring of process effluents released to sewer ........................................................... 98
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Table 2.13: Monitoring substances released from sources ................................................................ 98 Table 2.14: Monitoring of process variables ..................................................................................... 100 Table 3.1: Biochemical oxygen demand: water quality objectives in England, Wales and Northern Ireland ............................................................................................................................. 112 Table 3.2: Biochemical oxygen demand: water quality objectives in Scotland ................................. 112 Table 3.3: Halogen standards ........................................................................................................... 115 Table 3.4: Benchmark emission values ............................................................................................ 115 Table 3.5: Heavy metal standards .................................................................................................... 116 Table 3.6: Heavy metal benchmark emission values ........................................................................ 116 Table 3.7: Nitrogen oxides benchmark emission values ................................................................... 117 Table 3.8: Nutrients:water quality objectives in England, Wales and Northern Ireland .................... 118 Table 3.9: Nutrients:water quality objectives in Scotland .................................................................. 118 Table 3.10: Particulate and suspended solids in water ..................................................................... 120 Table 3.11: Particulate and suspended solids: benchmark emission values .................................... 120 Table 3.12: Sulphur dioxide: benchmark emission values ................................................................ 121 Table 3.13: Volatile organic compounds: benchmark emission values ............................................ 122 Table 4.1: Measurement methods for common substances to water ............................................... 131 Table 4.2: Measurement methods for other substances to water ..................................................... 132 Table 4.3: Measurement methods for air emissions ......................................................................... 134 Table 4.4: Equivalent legislation ....................................................................................................... 135
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Installations covered
Timescales
Emissions Key issues
Summary of releases
Technical overview
Impact Economics
1 Introduction The status and aims of this Guidance
This Guidance has been produced by the Environment Agency for England and Wales, with the Scottish Environment Protection Agency (SEPA) and the Environment and Heritage Service (EHS) in Northern Ireland - each referred to as “the Regulator” in this document. Its publication follows consultation with industry, Government departments and non-governmental organisations. It aims to provide Operators and the Regulator’s officers with advice on indicative standards of operation and environmental performance relevant to the industrial sector concerned, to assist the former in the preparation of applications for PPC Permits and to assist the latter in the assessment of those Applications (and the setting of a subsequent compliance regime). The use of techniques quoted in the guidance and the setting of emission limit values at the benchmark values quoted in the guidance are not mandatory, except where there are statutory requirements from other legislation. However, the Regulator will carefully consider the relevance and relative importance of the information in the Guidance to the installation concerned when making technical judgments about the installation and when setting Conditions in the Permit, any departures from indicative standards being justified on a site-specific basis. The Guidance also aims (through linkage with the Application Form or template) to provide a clear structure and methodology for Operators to follow to ensure they address all aspects of the PPC Regulations and other relevant Regulations, that are in force at the time of writing. Also, by expressing the Best Available Techniques (BAT) as clear indicative standards wherever possible, it aims to minimise the effort required by both Operator and Regulator to apply for and issue, respectively, a Permit for an installation.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Introduction Introduction Understanding UnderstandIPPC ing IPPC
Techniques Making an application
Installations covered
Timescales
Emissions Key issues
Summary of releases
Technical overview
Impact Economics
1.1 Understanding IPPC IPPC and the Regulations
Integrated Pollution Prevention and Control (IPPC) is a regulatory system that employs an integrated approach to control the environmental impacts of certain listed industrial activities. It involves determination by the Regulator of the appropriate controls for those industries to protect the environment, through a single permitting process. To gain a Permit, Operators have to demonstrate in their Applications, in a systematic way, that the techniques they are using or are proposing to use, are the Best Available Techniques (BAT) for their installation, and meet certain other requirements, taking account of relevant local factors. The essence of BAT is that the techniques selected to protect the environment should achieve an appropriate balance between environmental benefits and the costs incurred by Operators. However, whatever the costs involved, no installation may be permitted where its operation would cause significant pollution. IPPC operates under The Pollution Prevention and Control Regulations (for equivalent legislation in Scotland and N Ireland see Appendix 2). The three regional versions of the PPC Regulations implement in the UK the EC Directive on IPPC (96/61/EC). Further information on the application of IPPC/PPC, together with Government policy and advice on the interpretation of the English & Welsh Regulations, can be found in IPPC: A Practical Guide published by the Department for Environment, Food and Rural Affairs (Defra). Equivalent guidance on the Scottish Regulations is provided in PPC Regulations: A Practical Guide (Part A Activities), published by the Scottish Executive and SEPA. The Department of the Environment, Northern Ireland has published equivalent guidance on its Regulations.
Installation based, NOT national emission limits
The BAT approach of IPPC differs from regulatory approaches based on fixed national emission limits (except where General Binding Rules or Standard Permits are issued). The legal instrument that ultimately defines BAT is the Permit, and Permits can only be issued at the installation level.
Indicative BAT Standards
Indicative BAT standards are laid out in national guidance (such as this) and, where relevant, should be applied unless a different standard can be justified for a particular installation. BAT includes the technical components, process control, and management of the installation given in Section 2, and the benchmark levels for emissions identified in Section 3. Departures from those benchmark levels can be justified at the installation level by taking into account the technical characteristics of the installation concerned, its geographical location and the local environmental conditions. If any mandatory EU emission limits or conditions are applicable, they must be met, but BAT may go further (see “BAT and EQS” below). Some industrial sectors for which national guidance is issued are narrow and tightly defined, whilst other sectors are wide and diffuse. This means that where the guidance covers a wide variety of processes, and individual techniques are not described in detail, the techniques (and their associated emission levels) which might constitute BAT for a particular operation, are more likely to differ, with justification, from the indicative BAT standards than would be the case for a narrow, tightly-defined sector.
BAT and EQS
The BAT approach complements, but differs fundamentally from, regulatory approaches based on Environmental Quality Standards (EQS). Essentially, BAT requires measures to be taken to prevent emissions - and measures that simply reduce emissions are acceptable only where prevention is not practicable. Thus, if it is economically and technically viable to reduce emissions further, or prevent them altogether, then this should be done irrespective of whether or not EQSs are already being met. The BAT approach requires us not to consider the environment as a recipient of pollutants and waste, which can be filled up to a given level, but to do all that is practicable to minimise emissions from industrial activities and their impact. The BAT approach first considers what emission prevention can reasonably be achieved (covered by Sections 2 and 3 of this Guidance) and then checks to ensure that
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Introduction Introduction Understanding UnderstandIPPC ing IPPC
Techniques Making an application
Installations covered
Timescales
Emissions Key issues
Summary of releases
Technical overview
Impact Economics
the local environmental conditions are secure (see Section 4 on page 123 of this Guidance and also Guidance NoteIPPC Environmental Assessments for BAT). The BAT approach is therefore the more precautionary one because the release level achieved may be better than that simply required to meet an EQS. Conversely, if the application of indicative BAT might lead to a situation in which an EQS is still threatened, a more effective technique is required to be BAT for that installation. The Regulations allow for expenditure beyond indicative BAT where necessary, and, ultimately, an installation will only be permitted to operate if it does not cause significant pollution. Further advice on the relationship between BAT, EQSs and other related standards and obligations is given in IPPC: A Practical Guide, its Scottish equivalent, and also in Section 3. Assessing BAT at the sector level
The assessment of indicative BAT takes place at a number of levels. At the European level, the European Commission issues a “BAT reference document” (BREF) for each main IPPC sector. It also issues “horizontal” BREFs for a number of general techniques which are relevant across a series of industrial sectors. The BREFs are the result of an exchange of information between regulators, industry and other interested parties in Member States. Member States should take them into account when determining BAT, but they are allowed flexibility in their application. UK Sector Guidance Notes like this one take account of information contained in relevant BREFs and set out current indicative standards and expectations in the UK. At national level, techniques that are considered to be BAT should represent an appropriate balance of costs and benefits for a typical, well-performing installation in the sector concerned. They should also be affordable without making the sector as a whole uncompetitive, either within Europe or world-wide.
Assessing BAT at the installation level
When assessing applicability of sectoral indicative BAT standards at the installation level, departures may be justified in either direction. Selection of the technique which is most appropriate may depend on local factors and, where the answer is not self-evident, an installation-specific assessment of the costs and benefits of the available options will be needed. The Regulator’s guidance IPPC Environmental Assessments for BAT and its associated software tool may help with the assessment. Individual installation or company profitability (as opposed to profitability of the relevant sector as a whole) is not a factor to be considered, however. In the assessment of BAT at the installation level, the cost of improvements and the timing or phasing of that expenditure, are always factors to be taken into account. However, they should only be major or decisive factors in decisions about adopting indicative BAT where: •
the installation’s technical characteristics or local environmental conditions can be shown to be so different from those assumed in the sectoral assessment of BAT described in this guidance, that the indicative BAT standards may not be appropriate; or
•
the BAT cost/benefit balance of an improvement only becomes favourable when the relevant item of plant is due for renewal/renovation (eg. change to a different design of furnace when the existing furnace is due for a rebuild). In effect, these are cases where BAT for the sector can be expressed in terms of local investment cycles; or
•
a number of expensive improvements are needed. In these cases, a phasing programme may be appropriate - as long as it is not so drawn out that it appears to be rewarding a poorly performing installation.
In summary, departures by an individual installation from indicative BAT for its sector may be justified on the grounds of the technical characteristics of the installation concerned, its geographical location and the local environmental conditions - but not on the basis of individual company profitability, or if significant pollution would result. Further information on this can be found in IPPC: A Practical Guide and IPPC Part A(1) Installations: Guide for Applicants, or the equivalent Scottish Guidance. Innovation
The Regulators encourage the development and introduction of innovative techniques that advance indicative BAT standards criteria, ie. techniques which have been developed on a scale which reasonably allows implementation in the relevant sector, which are technically and economically viable
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and which further reduce emissions and their impact on the environment as a whole. One of the main aims of the PPC legislation is continuous improvement in the overall environmental performance of installations as a part of progressive sustainable development. This Sector Guidance Note describes the indicative BAT standards at the time of writing but Operators should keep up-to-date with improvements in technology - and this Guidance note cannot be cited as a reason for not introducing better available techniques. The technical characteristics of a particular installation may also provide opportunities not foreseen in the Guidance, and as BAT is determined at the installation level (except in the case of General Binding Rules (GBRs)), it is a requirement to consider these even where they go beyond the indicative Standards. New installations
Indicative BAT standards apply, where relevant, to both new and existing installations, but it will be more difficult to justify departures in the case of new installations (or new activities in existing installations) - and for new activities, techniques which meet or exceed indicative BAT requirements should normally be in place before operations start.
Existing installations standards
For an existing installation, it may not be reasonable to expect compliance with indicative BAT standards immediately if the cost of doing so is disproportionate to the environmental benefit to be achieved. In such circumstances, operating techniques that are not at the relevant indicative BAT standard may be acceptable, provided that they represent what is considered BAT for that installation and otherwise comply with the requirements of the Regulations. The determination of BAT for the installation will involve assessment of the technical characteristics of the installation and local environmental considerations, but where there is a significant difference between relevant indicative BAT and BAT for an installation, the Permit may require further improvements on a reasonably short timescale.
Existing installations upgrading timescales
Where there are departures from relevant indicative BAT standards, Operators of existing installations will be expected to have upgrading plans and timetables. Formal timescales for upgrading will be set as Improvement Conditions in the Permits. See Section 1.4.2 on page 7 for more details.
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Installations covered
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Emissions Key issues
Summary of releases
Technical overview
Impact Economics
1.2 Making an application A satisfactory Application is made by: •
addressing the issues in Sections 2 and 3 of this guidance;
•
assessing the environmental impact described in Section 4 (and in England and Wales Environmental Assessment and Appraisal of BAT (IPPC H1));
•
demonstrating that the proposed techniques are BAT for the installation.
In practice, some Applicants have submitted far more information than was needed, yet without addressing the areas that are most important - and this has led to extensive requests for further information. In an attempt to focus application responses to the areas of concern to the Regulator, Application forms (templates) have been produced by the Environment Agency, by SEPA and by EHS in N Ireland. In addition, as the dates for application have approached, the operators in most industrial sectors in England and Wales have been provided with Compact Discs (CDs) which contain all relevant Application Forms, technical and administrative guidance, BREFs and Assessment tools, hyper-linked together for ease of use. For Applicants with existing IPC Authorisations or Waste Management Licences, the previous applications may provide much of the information for the PPC application. However, where the submitted Application refers to information supplied with a previous application the Operator will need to send fresh copies - though for many issues where there is a tendency for frequent changes of detail (for example, information about the management systems), it will be more appropriate simply to refer to the information in the Application and keep available for inspection on site, up-to-date versions of the documents. For further advice see IPPC Part A(1) Installations: Guide for Applicants (for England and Wales) or PPC Part A Installations: Guide for Applicants (for Scotland) or the equivalent Northern Ireland guide for Applicants.
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Installations Installations covered covered
Timescales
Emissions Key issues
Summary of releases
Technical overview
Impact Economics
1.3 Installations covered This Guidance relates to installations containing the activities listed below, as described in Part A(1) of Schedule 1 to the The Pollution Prevention and Control Regulations. The schedules of listed activities are slightly different in Scotland and Northern Ireland so for their equivalent Regulations see Appendix 2 Section 6.8 (e)
Treating and processing milk, the quantity of milk received being greater than 200 tonnes per day (average value on an annual basis).
The installation includes the main activities as stated above and associated activities which have a technical connection with the main activities and which may have an effect on emissions and pollution. They include, as appropriate: •
Raw milk reception
•
Pasteurisation
•
Cheesemaking
•
Butter
•
Yogurt production
•
Packing
•
Cleaning
•
Refrigeration
•
the control and abatement systems for emissions to all media;
•
the power plant
The installation will also include associated activities which have a technical connection with the main activities and which may have an effect on emissions and pollution, as well as the main activities described above. These may involve activities such as: •
the storage and handling of raw materials;
•
the storage and despatch of finished products, waste and other materials;
•
the control and abatement systems for emissions to all media;
•
waste treatment or recycling.
Environment Agency advice on the composition of English or Welsh installations and which on-site activities are to be included within it (or them) is given in its guidance document The Pollution Prevention and Control Regulations (SI 2000 No. 1973) (www.hmso.gov.uk).. Operators are advised to discuss the composition of their installations with the Regulator before preparing their Applications.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Timescales Timescales
Installations covered
Emissions Key issues
Summary of releases
Technical overview
Impact Economics
1.4 Timescales
1.4.1 Permit review periods Permits are likely to be reviewed as follows: •
for individual activities not previously subject to regulation under IPC or Waste Management Licensing, a review should be carried out within four years of the issue of the PPC Permit
•
for individual activities previously subject to regulation under IPC or Waste Management Licensing, a review should be carried out within six years of the issue of the IPPC Permit
However, where discharges of Groundwater List I or List II substances have been permitted, or where there is disposal of any matter that might lead to an indirect discharge of any Groundwater List I or II substance, a review must be carried out within four years as a requirement of the Groundwater Regulations. These periods will be kept under review and, if any of the above factors change significantly, they may be shortened or extended.
1.4.2 Upgrading timescales for existing plant Existing installation timescales
Unless subject to specific conditions elsewhere in the Permit, upgrading timescales will be set in the Improvement Programme of the Permit, having regard to the criteria for improvements in the following two categories: 1
Standard “good-practice” requirements, such as, management systems, waste, water and energy audits, bunding, housekeeping measures to prevent fugitive or accidental emissions, good wastehandling facilities, and adequate monitoring equipment. Many of these require relatively modest capital expenditure and so, with studies aimed at improving environmental performance, they should be implemented as soon as possible and generally well within 3 years of issue of the Permit.
2
Larger, more capital-intensive improvements, such as major changes to reaction systems or the installation of significant abatement equipment. Ideally these improvements should also be completed within 3 years of Permit issue, particularly where there is considerable divergence from relevant indicative BAT standards, but where justified in objective terms, longer time-scales may be allowed by the Regulator.
Local environmental impacts may require action to be taken more quickly than the indicative timescales above, and requirements still outstanding from any upgrading programme in a previous permit should be completed to the original time-scale or sooner. On the other hand, where an activity already operates to a standard that is close to an indicative requirement a more extended time-scale may be acceptable. Unless there are statutory deadlines for compliance with national or international requirements, the requirement by the Regulator for capital expenditure on improvements and the rate at which those improvements have to be made, should be proportionate to the divergence of the installation from indicative standards and to the environmental benefits that will be gained.
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Emissions Key issues
Summary of releases
Technical overview
Impact Economics
The Operator should include in the Application a proposed programme in which all identified improvements (and rectification of clear deficiencies) are undertaken at the earliest practicable opportunities. The Regulator will assess BAT for the installation and the improvements that need to be made, compare them with the Operator’s proposals, and then set appropriate Improvement Conditions in the Permit All improvements should be carried out at the earliest opportunity and to a programme approved by the Regulator. Any longer timescales will need to be justified by the Operator. Table 1.1: Specific timescale improvements
Improvement
By whichever is the later of: Activities under Section 6.8di (see Section 1.3) – Animal raw materials
Activities under Section 6.8dii and 6.8e (see Section 1.3) – Vegetable raw materials and milk
Waste minimisation audit in accordance with Section 2.4.2 on page 74
31 August 2005
31 March 2006
or one year from the issue of the Permit
or one year from the issue of the Permit
A review of water use (water efficiency audit) in accordance with Section 2.4.3 on page 77
31 August 2005
31 March 2006
or one year from the issue of the Permit
or one year from the issue of the Permit
The Applicant should include a proposed timetable covering all improvements.
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Installations covered
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Emissions Key Keyissues issues
Summary of releases
Technical overview
Impact Economics
1.5 Key issues An assessment of the issues indicates that there are no areas where there is a fundamental clash between good environmental practice and good business practice. However the implementation of pollution prevention and control measures represents a balance between environmental protection and costs incurred by the operators and will not always result in cost savings for the operator. Waste minimisation Commercial considerations mean that the controls of parameters such as process yield and product wastage are usually understood. These parameters are also key pollution prevention issues as product loss accounts for a significant proportion of the sectors environmental impact. Water use The sector is a significant water consumer, the vast majority of which is used for cleaning, both manually and in CIP (cleaning in place) systems, which are widely used throughout the industry. In addition to minimising the use of a raw material, measures to optimise water use will be important pollution prevention measures relating to effluent management. There are a number of opportunities to either reuse water (for example low-grade wash waters) or to recycle water from for example membrane systems (also see Hygiene and Food Safety). Releases associated with energy use The industry is a major energy user. There remain significant opportunities for reduction of emissions caused by energy use and choice of energy source (CO2, SOx, NOx, etc. contributing in particular to global warming and acidification). The dairy industry has entered into a Climate Change Levy Agreement with the Government, dated the 6th March 2001. The applicability of techniques and standards for IPPC is explained in Section 2.6. Emissions to air It is an inherent factor within the food, drink and dairy industries that emissions of VOC and odour arise, for example from drying and other processes, including effluent treatment. Emissions of dust and particulate material can also be a factor from milk powder drying and the transfer of materials. Odour emissions can be problematic, not only because of the sometimes subjective nature of the problem, but as emissions tend to be fugitive. Other fugitive emissions considerations include those potentially arising from refrigeration, cooling and effluent treatment systems. Effluent management The composition of the effluent within the dairy industry is very highly variable, dependant on the activity, working patterns, product wastage and cleaning systems. Of these the most important is keeping raw materials, intermediates, product and by product out of the wastewaters, by controlling product wastage and cleaning processes. Accident risk All types of milk, cream and most other dairy products have a very high oxygen demand and spills and leaks into the water environment are serious events. In addition to normal spills and process leaks, they typically arise from for example, overfilling of vessels and failure of containment, wrong drainage connections and blocked drains. Hygiene and food safety Health and safety and product quality issues apply to industry as a whole, but hygiene and food safety is of fundamental importance to the dairy sector. Consequently particular attention must be given to these considerations when specifying particular techniques, especially in relation to pollution prevention
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Installations covered
Timescales
Emissions Key Keyissues issues
Summary of releases
Technical overview
Impact Economics
measures, in for example measures relating to water use, cleaning and reuse and recycling of water. Industry experience of managing risk in relation to hygiene and food safety issues is a sound basis for environmental management issues.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Timescales
Key issues
Summary Summaryof of releases releases
Technical overview
Impact Economics
Pasteurisation and sterilisation
Drying and evaporation
Cleaning and sanitisation
Storage and dispatch of finished
Cooling and refrigeration
Boiler and Combustion plant
Effluent plant (Note 1)
1.6 Summary of releases Mixing, blending and homogenisation (solid/liquid)
Installations covered
-
-
-
-
-
-
-
-
-
A
-
Oxides of nitrogen & car- bon
-
-
-
-
-
-
-
-
-
-
Particulate/TSS
AW
W
AW
W
W
AW
AW
AW
-
A
W
COD/BOD
W
W
-
W
W
W
W
W
-
-
W
Odour
A
AW
W
A
AW
A
A
A
-
A
A
Biocides
-
W
-
-
-
-
W
-
-
-
W
Dispersants & surfactants
-
-
-
-
-
-
W
-
-
-
-
Phosphates & nitrates
-
-
-
-
-
W
-
-
-
-
Refrigerants
-
-
-
-
-
-
AW
W
W
-
-
-
-
-
-
-
-
L
SOURCE
RELEASES
Oxides of sulphur
Cutting and
Making an application
Emissions
Storage and handling of raw
Understanding IPPC
Techniques
Mixing and blending (powders and
Introduction Introduction
-
Ammonia, HCFC, Glycol Sludges KEY
A – Release to Air, W – Release to Water, L – Release to Land
Note: 1. Most of the other releases to water pass through the effluent treatment plant (ETP). Included here are only those which arise as a direct result of the operation of the ETP. 2. Releases to air usually result in a subsequent, indirect emission to land and can therefore affect human health, soil and terrestrial ecosystems. 3. Releases identified above to water can all also appear in the effluent treatment sludge (see Section 2.5 on page 82).
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Installations covered
Timescales
Emissions Key issues
Summary of releases
Technical Technical overview overview
Impact Economics
1.7 Technical overview Figure 1.1: Overview of the activities within the milk processing sector
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Installations covered
Timescales
Emissions Key issues
Summary of releases
Technical overview
Impact Economics Economics
1.8 Economics The food and drink industry is an important part of the manufacturing industry in the UK. It is the largest industrial sector in turnover terms: with a market value in excess of £90 billion. . It is a large and diverse sector and accounts for about 9% of manufacturing output and a commensurate fraction of the jobs available in UK manufacturing. Table 1-1 shows a breakdown of the main activities by SIC code and it is clear that a wide range of activities is represented. Almost half of the milk sold to first-hand buyers under wholesale contract is used to supply the liquid market, with the remainder being processed into a widening range of milk products. Much of the this manufactured product is sold to consumers (e.g. as cream, butter or cheese) but large quantities are also used by food manufacturers as ingredients in the production of a vast range of foods. At one time, much of the by-product (such as skim milk and whey) was of minimal value and was fed to livestock, particularly at times of seasonal surplus. However, such end-uses have diminished as the industry has sought to extract the maximum value from each litre of milk produced and as quotas have sharply reduced milk output. As a result, the vast majority of milk leaving the farm is now destined for human consumption. However, as the table below suggests, there is a mix in size of the dairy companies within England and Wales, with around 38% of them processing in excess of 30 million litres/year, although many more smaller companies processing up to 30 million litres/year. Size Band
No. of Companies processing milk
Percent of Total
1 and under
15
13.3%
Between 1 and 10
35
31.0%
Between 10 and 30
19
16.8%
Between 30 and 100
23
20.4%
Over 100
21
18.6%
TOTAL
113
100%
(million litres/year)
The dairy industry is extremely complex and can be characterised as follows: •
there are a wide range of unit operations
•
some of the unit operations such as pasteurisation, are not well known outside of the immediate industry
•
the consumer market is becoming more sophisticated and demanding
•
there is a continual need for process innovation
•
plant and equipment needs to be flexible to respond to changes in demand
•
quality of production is paramount (and is matched only by pharmaceutical standards)
These factors contribute to making the plant and equipment of dairy food production increasingly complex. Associated abatement equipment needs to be equally flexible and adaptable. There is a potential reluctance to invest in large capital abatement plant when it may be made redundant by a change in the production process, however, changes in the process are opportunities for environmental investment. The food and dairy market-place is characterised by: •
Short time-to-market and competitiveness, where the time between product conception and delivering the product to the market-place is continually reducing; against a background of increasing competitiveness and reduced margins, the emphasis during product development is on the production process itself.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Installations covered
Timescales
Emissions Key issues
Summary of releases
Technical overview
Impact Economics Economics
•
Product innovation with more and more product variations available now to the consumer; this implies that existing products face stiffer competition and product lifetimes become shorter, with the result that manufacturing processes and production lines require change more frequently.
•
Product complexity with the introduction of new flavours, mixtures and combinations of products, pre-prepared products, new packaging, etc..
•
The production runs also become shorter as tastes change more frequently.
•
Raw materials are generally natural and are therefore more variable than other sectors.
All of these factors contribute to the dynamic and complex nature of dairy food production. While this can imply the potential for more frequent upgrade of processing equipment, it has the drawback of providing a degree of instability. With the end of the end of the Milk Marketing schemes in 1994, the milk market in the UK was opened up for greater competition, both for producers selling their milk and for the processors buying the milk. However, the price ex. farm has dropped significantly over the past few years, as the table below shows: YEAR
UK Farm Gate Prices, pence per litre (including bonus payments)
1995
24.94
1996
25.02
1997
22.12
1998
19.37
1999
18.35
2000(1)
16.89
N.B.: Data from “Dairy Facts and Figures” see Ref. 8. 2000 data based on January to November only This highlights the drop in revenues experienced by the farmers, which has also resulted in a drop in milk prices at the supermarkets. The current (December 2001) cost of a 4-pint polybottle (2.27 Litres) is 93pence, which equates to a cost of c. 40 pence per litre to the consumer. This means that the simple milk processing companies, those who take farm milk for liquid consumption in either polybottles for the supermarkets or glass for the declining doorstep delivery market operate at low margins. This requires them to be very efficient in all manner of production, not least in wastage of raw materials. The most successful companies are therefore the most efficient. Considering the manufacturing companies, there is more scope for adding value to their products and hence profit margins are greater.
1.8.1 Sector costs Costs, both capital and revenue, for effluent treatment at dairy plants are site specific, and can vary markedly depending on effluent volumes and loadings, as well as ancillary items such as: •
Landscaping, fencing or planting requirements
•
Access roadways
•
Ground conditions (e.g., piling requirements)
However, in order to provide some specific information, some example projects and costs are provided below.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Introduction Introduction
Understanding IPPC
Techniques Making an application
Installations covered
Timescales
Project
Emissions Key issues
Summary of releases
Total Cost
Technical overview
Impact Economics Economics
Crude Effluent
Final Effluent
Plant Outline
at 2001 prices Volume m3/day
Loading kgCOD/ d
A
£660,000
300
1,000
40:60
Primary screening, 4,800m3 HDPE-lined lagoon, 8.5m diameter settlement tank
B
£2.8 million
1,230
5,240
20:30:5
Anoxic tank, 13,000m3 concrete tank, 15m diam settlement tank and sand filters
C
£1.0 million
1,800
6,720
25:25
Retrofit to existing plant, including 3,000m3 aeration tank, 1,000m3 balance tank, 2 settlement tanks
D
£200,000
500
2,000
25:40:25
Retrofit to remove old technology filter plant, replace with activated sludge
E
£160,000
1,000
N/A
N/A
Pump sump and fat trap, 300m3 balance and 50m3 divert tank and control equipment
N.B.: Costs assume 2001 base, with inflationary increases of 5%pa. In all cases, it is recommended that competent professional assistance is sought to provide a detailed design specification, against which prospective contractors can quote. This provides for competitive quotations on a like-for-like basis. For revenue costs, again the actual costs will be site specific but as a guideline, the following figures provide a reference: •
Conventional Activated sludge = 16pence/kgCOD treated
•
Conventional filtration plants = 12pence/kgCOD treated
•
MBR activated sludge = 19pence/kgCOD treated
These costs are based on electricity and sludge disposal only. As a comparison, the average cost of discharging dairy effluent to sewer for treatment at a local sewage works by the Water Service plc will be 56 pence/kgCOD, assuming 3,000 mg/l COD and 800 mg/l TSS. This is based on the standard Trade Effluent Charging tariffs and does not include the Scottish water companies.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction Economics The main activities and abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
2 Techniques for pollution control BAT Boxes to help in preparing applications
To assist Operators and the Regulator’s officers in respectively making and determining applications for PPC Permits, this section summarises the indicative BAT requirements (i.e. what is considered to represent BAT for a reasonably efficiently operating installation in the sector). The indicative BAT requirements may not always be absolutely relevant or applicable to an individual installation, when taking into account site-specific factors, but will always provide a benchmark against which individual Applications can be assessed. Summarised indicative BAT requirements are shown in the “BAT boxes”, the heading of each BAT box indicating which BAT issues are being addressed. In addition, the sections immediately prior to the BAT boxes cover the background and detail on which those summary requirements have been based. Together these reflect the requirements for information laid out in the Regulations, so issues raised in the BAT box or in the introductory section ahead of the BAT box both need to be addressed in any assessment of BAT. Although referred to as indicative BAT requirements, they also cover the other requirements of the PPC Regulations and those of other Regulations such as the Waste Management Licensing Regulations (see Appendix 2 for equivalent legislation in Scotland and Northern Ireland) and the Groundwater Regulations, insofar as they are relevant to PPC permitting. For further information on the status of indicative BAT requirements, see Section 1.1 on page 2 of this guidance or Guidance for applicants. It is intended that all of the requirements identified in the BAT sections, both the explicit ones in the BAT boxes and the less explicit ones in the descriptive sections, should be considered and addressed by the Operator in the Application. Where particular indicative standards are not relevant to the installation in question, a brief explanation should be given and alternative proposals provided. Where the required information is not available, the reason should be discussed with the Regulator before the Application is finalised. Where information is missing from the Application, the Regulator may, by formal notice, require its provision before the Application is determined. When making an Application, the Operator should address the indicative BAT requirements in this Guidance Note, but also use the Note to provide evidence that the following basic principles of PPC have been addressed: •
The possibility of preventing the release of harmful substances by changing materials or processes (see Section 2.1 on page 17), preventing releases of water altogether (see Section 2.2.2 on page 46), and preventing waste emissions by reuse or recovery, have all been considered, and
•
Where prevention is not practicable, that emissions that may cause harm have been reduced and no significant pollution will result.
This approach should assist Applicants to meet the requirements of the Regulations to describe in the Applications techniques and measures to prevent and reduce waste arisings and emissions of substances and heat - including during periods of start-up or shut-down, momentary stoppage, leakage or malfunction.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
2.1 The main activities and abatement (includes “directly associated activities” in accordance with the PPC Regulations)
Indicative BAT requirements: 1
See each subsection of this section 2.1.
2.1.1 In-process controls Improved process control inputs, conditions, handling, storage and effluent generation will minimise waste by reducing off-specification product, spoilage, loss to drain (for example, fitting a level switch, float valve, or flow meter will eliminate waste from overflows), overfilling of vessels, water use and other losses. Product loss or wastage is a significant benchmark for the dairy industry and is a useful guideline for an operator to assess the performance of the installation against industry standards. In assessing the wastage efficiency of milk processing sites, two co-efficients are used to measure milk loss and water usage: %COD (or milk) loss to effluent (measured as COD) Effluent:Milk Intake Ratio (or Water:Milk Intake Ratio) These techniques have been used for many years, and have proven themselves much more accurate than trying to assess %milk loss using yield calculations or mass balances, which are used by the majority of the dairy companies in the UK. Mass balance or yield figures often give negative variances (milk is gained instead of lost – which is clearly impossible), whereas this never occurs when actually measuring the loss to effluent using %COD loss techniques. To calculate the %COD loss to effluent, the procedure is to use effluent loadings and compare this against the milk intake, converted to kgCOD, as follows:
%COD loss =
Effluent Load, kgCOD
x 100
Milk Intake, as kgCOD To do this we usually consider the COD equivalent of milk as 220 kgCOD/m3, or 220,000 mg/l, although this can vary depending on butterfat content, SNF ratios, etc. As an example, consider a site with a the following conditions: Milk intake:650,000 lpd Effluent volume:1,200 m3/day
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Effluent loading:3,650 kgCOD/day
3,650 kgCOD %COD loss =
x 100 650m3 x 220
%COD loss = 2.55% The effluent:milk ratio (or water:milk ratio) is simply a ratio between the amount of effluent or water used compared against milk or product intake. Again, this allows for comparison across similar processing sites. Using the example above, the effluent:milk ratio would be 1,200/650 or 1.84:1.0, which means that 1.84 litres of effluent are generated for every litre of milk processed. Good wastage co-efficients for simple milk processing sites would be c. 1.5% milk loss to effluent and c. 1.5:1 effluent:milk ratio. Some sites with excellent wastage management can (and do) achieve less than 1% milk loss to effluent and an effluent:milk ratio of 1:1, or less. Sites with poor wastage management, or inefficient processing profiles, can have losses in excess of 5% milk loss. Clearly, these figures can only be a guide as actual wastage performance depends on many other factors including product type and mix, processing profiles, plant utilisation efficiency, age of processing equipment and control systems, and effluent pressure. Using these techniques as part of the wastage monitoring for the site will allow the operator to demonstrate historical wastage performance and highlight improvements as part of an overall wastage control campaign The factors that influence wastage control on a dairy include, but are not limited to the following: •
Management awareness and motivation to improve wastage
•
Operator awareness
•
Measurement of losses
•
Constraints on the effluent disposal route
•
Process design of the CIP systems
•
Plant utilisation efficiency and downtime
•
Willingness to invest time money and effort
For example, consider a small traditional cheese-making factory, with a high desire to implement wastage control to reduce Trade Effluent Charges, and having a committed management team. Despite the oldest of equipment and processes within the dairy, they achieved losses measured at 0.88% COD loss and an effluent:milk ratio of 0.89. Consider, also a very large multiproduct dairy with a milk intake capacity of over 1,000,000 litres/day, but only handling around 380,000 litres/day. This plant has a large effluent plant (due to its’ maximum capacity) but with little pressure to monitor losses as the effluent discharge is well within specification. The losses here are 8.44% COD loss and 3.85 effluent:milk ratio. Finally, consider a another large manufacturing dairy, with a very focussed management team, with effluent pressure due to an old, not very efficient effluent plant discharging into a trout river. The factory was equipped with simple but effective wastage monitoring, including individual drain lines to enable checking on CIP systems, etc., and achieved 0.77% COD loss and a 1.21 effluent:milk ratio. Despite these figures, further on-site survey work highlighted savings of £149,000 pa in product, water and effluent costs. To successfully tackle wastage control and maintain impetus within a factory requires a consideration of all the points detailed above. In addition, a systematic approach is essential for action to be effective, and the one outlined below will provide some guidance:
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Determine the size of the problem - this requires effluent monitoring to be set up to provide information on wastewater loadings (kgCOD and volume). This information can be converted into product or money equivalents, and the loss co-efficients mentioned above can be calculated. “If you’re not monitoring itÖ.you can’t manage it” Set targets/objectives/KPI’s - this could be a reduction in daily kgCOD or volume, a percentage reduction in Trade Effluent Charges, or any other specific objective. As with all objectives, the target should be measurable, realistic and agreed by those who are going to implement it and achievable. Investigate/isolate high loss areas - this is often where factory personnel provide the best input for suggestions and information. Specific machines or departments can be assessed or a complete factory effluent audit conducted, itemising the effluent loadings from all manufacturing and cleaning processes. Catching people doing things RIGHT can be key to ensuring their commitment and interest. Action - this stage may mean an input of capital or revenue expenditure for pipework or recovery systems, but this can be offset against the potential savings. All financial input should have a return on investment, and following completion this should be audited to prove the savings. Often changes in working practices or techniques will provide savings without the need for any additional expenditure. Continue monitoring and review - has the action worked? Have we reached target? Do we re-set our target for further improvements? Selection of process techniques also has a bearing on product loss. While selection is primarily based on product requirements, it will also have implications for pollution. Operators should consider this trade off when implementing BAT. . It is important that process monitoring and control equipment selected is designed, installed, calibrated and operated so that it will not interfere with hygiene conditions in the production process and itself lead to product loss and waste. Measures, which should be implemented as appropriate, include: Table 2.1: Process monitoring and control equipment
Technique
Application
Outcome
Temperature measurement
Storage and processing vessels, transfer lines, etc.
Reduced deterioration of materials and out-ofspecification products
Pressure Measurement
Indirect control of other parameters, for example flow or level
Minimise waste from material damaged by shear friction forces
Level measurement
Storage and reaction vessels
Prevent storage overflow of materials and associated wastage from storage or reaction tanks; minimise waste from transfer losses in inaccurate batch recipes in vessels; and minimise outof-date stock or production losses due to insufficient material
Flow measurement
Transfer lines
Accurate addition of materials to processing vessels and minimise excessive use of materials and formation of out-of-specification products
Steam supply
Maintain correct operating temperature and minimise waste from underheated or overheated materials and products
Cleaning systems
Control and optimise water use, and minimise effluent generation
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Table 2.1: Process monitoring and control equipment
Flow control
Constant flow valves
Control flow rate to water ring vacuum pumps
• Flow regulators
Control process water flow rates for specific processes
The most accurate way of measuring milk intake into most sites is the use of a weighbridge, although this is sometimes not the most convenient approach. Weighbridges are normally very accurate with measurement errors typically less than 0.05%. The move within the UK dairy industry to the use of insitu tanker flow meters has introduced significant errors into milk loss measurement, as it is now generally accepted that unless the flow meter error on the tanker meter is greater than 60 litres, this discrepancy is acceptable. An error of 60 litres on a volume of say 15,000 litres equates to 0.4%, which falls well below the level required for accurate measurements of factory losses, particularly when using yield or mass balance calculations. Packing line efficiency Poorly designed and operated packing lines cause many companies to lose as much as 4% of their product and packaging. To improve efficiency and productivity and to reduce wastage, individual machines should be correctly specified so that they work together as part of an efficient overall design.
2.1.2 Materials handling, unpacking, storage Summary of the activities
Materials handling applies to the receipt, storage and internal conveying of raw materials, intermediate products and final products. Solid materials are commonly delivered in bags on pallets. They are transported with forklift trucks, and stored in a store. The same holds for liquid ingredients in containers. Larger amounts of solid raw materials and powders are mostly delivered in bulk trucks. These are off-loaded directly for processing or stored in silos. Solid raw materials can be conveyed by water (vegetables, roots, tubers), by air (solid particles, powder) or by conveyer belts and elevators. Conveyor systems include: •
gravity systems (direct flow to receptacle)
•
mechanical systems (belts, screw conveyors or buckets)
•
pneumatic systems (positive or negative pressure systems)
•
fans
Liquid raw materials are normally delivered in bulk tankers and then pumped into storage tanks. Internal transport of liquid is carried out by pumping through, sometimes extensive and complex, piping systems. Environmental impact
Water: Leakages, for example from pipework or flume systems. Effluent from cleaning. Results in the release of suspended solids (both organic and/or inorganic) and soluble compounds (both organic and/ or inorganic) to water, which leads to a considerable biochemical oxygen demand and turbidity. Air: Potential emissions from vessel vents whilst filling, which could consist of particulates, gases and odours. Dust and particulate from conveyor systems. Land: Deposition from emissions to air and contamination from leaking pipework. Waste: Residues from vessels and other material handling equipment. Reworked for sale as animal feed where possible.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Energy: Materials handling is almost exclusively electrically driven. Accidents: Spillage from, for example, flume systems or cleaning activities or transfer of materials, for example containers being dropped. Overfilling of storage vessels. Noise: No issue from vessels and static conveying equipment, but there might be noise from certain types of vehicle-mounted blowers used to discharge solids and liquids from road vehicles into silos and other vessels. Safety horns on forklift trucks may also be a factor.
Indicative BAT requirements for storage and handling of materials: 1
The main control issues are: • cleaning techniques – see Section 2.1.16 on page 36 • air emissions from conveyors – see Section 2.5 on page 82 • accidents, for example overfilling of storage silos – see Section 2.8 on page 90
2
No further issues are identified.
2.1.3 Pasteurisation, Sterilisation and UHT Summary of the activities
Heat treatment of products is one of the main techniques used in the food industry for conservation. Within the dairy industry, heat treatment kills all micro-organisms capable of causing disease as well as improving the keeping quality of the end product. In heat treatment various time/temperature combinations can be applied, depending on product properties and shelf life requirements. In pasteurisation generally a heating temperature below 100 ×C is applied (72 to 75oC for 15 seconds for High Temperature Short Time pasteurisation), this means a reduction of enzyme and bacterial activity and a stable shelf life. Sterilisation commonly means a heat treatment over 100oC for such times that a longer shelf life is achieved. UHT means Ultra High Temperature treatment, usually 135 to 140oC during very short times; and was pioneered on milk products to produce extended shelf life. Generally for sterilisation the milk product is canned or bottled and then heat-treated in a retort in hot water (under overpressure) or steam. Sterilising retorts may be batch or continuous in operation.
Environmental impact Air:
Potential for fugitive losses from refrigeration systems.
Water:
Once-through cooling” post heat treatment requires substantial quantities of cooling water. Fouling of heat transfer surfaces requires cleaning.
Land:
No direct impacts.
Waste:
Product residues and concentrated flushes can be collected for recovery or animal feed.
Energy:
Energy required in the form of steam or hot water treatment and for cooling. Cooling can be accomplished by once-through cooling or with a recirculating chilled water system. The latter will involve a mechanical refrigeration system. Most dairy pasteurisers now use a regenerative heat exchangers which can be up to 96% energy efficient
Accidents:
Not applicable.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Noise:
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Not applicable.
BAT for pasteurisation etc. Indicative BAT requirements for heat treatment processes: 1
The main control issues are: • water use – see Section 2.5 on page 82 – the operator should justify why the reuse of ‘once through cooling’ waters is not possible. • cleaning techniques – see Section 2.1.16 on page 36 • fugitive emissions to air (refrigerants) – see Section 2.8 on page 90 • energy efficiency – see Section 2.8 on page 90 for use of regenerative heat exchangers
2
No further issues are identified.
2.1.4 Evaporation Summary of the activities
Evaporation is the partial removal of water from liquid food by boiling. Milk or milk products can be evaporated to produce concentrated, condensed, or evaporated products. Water is usually removed from liquid milk in an evaporator prior to drying. Milk products are normally condensed from an initial solids content of 9 to 13% to a final concentration of 40 to 50% total solids before drying. Steam or vapour is usually used as heating medium. The latent heat of condensation is transferred to the liquid to raise its temperature to the boiling point and evaporate the water. The vapour is then removed from the surface of the boiling liquid. Evaporation systems may be single-stage or multi-stage (also called “effects”) with 2, 3 or more evaporator or vacuum units. In multi-stage evaporators the effects operate at decreasing pressure as the product moves through the stages. These stages are usually under vacuum so that evaporation and boiling temperatures are lower than at atmospheric pressure, so as to reduce heat input and damage to the products. Other options to reduce energy consumption by re-using heat contained in vapours include: •
vapour recompression;
•
preheating using the vapour to heat incoming feedstock or condensed vapour is used to raise steam in a boiler.
Periodical chemical cleaning is carried out in order to ensure clean surfaces and an efficient heat transfer. The cleaning frequency is, depending on product and evaporator type, from 8 to more than 48 hours. Environmental impact Air:
Odour and particulate arising from incondensable gases vented to ensure efficient heat transfer and entrainment, where a fine mist of concentrate is produced during violent boiling.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Water:
Evaporation produces copious quantities of hot water, suitable for boiler feed make-up and potential re-use within the factory (e.g. CIP make-up). During processing the heat exchange surfaces become fouled and require cleaning to prevent reduction in heat transfer. Cleaning is carried out using alkaline and acid solutions, with the choice depending on the composition of the deposits. Vacuum pumps can use “once through” cooling water.
Land:
No direct impacts.
Waste:
Product removed by cleaning can result in high COD loadings.
Energy:
Steam raising requiements
Accidents:
Not applicable.
Noise:
Noise is often produced from evaporation and will be principally generated by the thermo compressor, the mechanical compressor, the steam ejectors and the high velocity of the fluids in the piping.
Indicative BAT requirements for evaporation: 1
The main control issues are: • cleaning techniques – see Section 2.1.16 on page 36 • emissions to air (dust and odour) – see Section 2.8 on page 90 • effluent treatment – see Section 2.8 on page 90, the use of ‘once through’ vacuum pump cooling water should be avoided • consideration required for condensate re-use system – see Section 2.8 on page 90 • energy efficiency – see Section 2.8 on page 90
2
No further issues are identified.
2.1.5 Drying Summary of the activities
Drying is defined as the application of heat under controlled conditions to remove the water present in liquid foods by evaporation yielding solid products with extended shelf life. Skim milk powder has a maximum shelf life of about 3 years, with whole milk powder around 6 months, due to the fat oxidising during storage. Two different principles can be applied for drying, both of which are used in milk processing.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Hot air drying
Surface drying by heat conduction through a heat transfer system
Hot air is used as heating medium and is in direct with the liquid product. The heat transferred from the hot air to the product causes water evaporation.
• bin dryers,
The heating medium is not in contact with the wet food but separated from it by a heat transfer surface. The heat is transferred by conduction through the surface and by convection from the hot surface to the food product for evaporating and removing water from the food. This has two main advantages compared to hot air dryers:
• tray dryers,
• less air volume and therefore higher thermal
The main types of hot air dryers are:
efficiency,
• tunnel dryers,
• and the process may be carried out in absence
• conveyor (belt dryers),
of oxygen.
• fluidised bed dryers,
The two main types of surface dryers are:
• kiln dryers,
• drum (roller dryers),
• pneumatic dryers,
• vacuum band/vacuum shelf dryers.
• rotary dryers, • spray dryers, Fluidised bed dryers have present several advantages: •
good control over drying conditions;
•
relatively high thermal efficiencies and high drying rates;
•
very high rates of heat and mass transfer and consequently short drying times;
•
drying can take place with air temperatures below 100oC.
Ultrasonic and freeze-drying are developing alternative techniques for certain foods. Environmental impact Air:
Spray dryers, for example, have air inlet temperatures from about 150 to 250oC decreasing to an outlet temperature of about 95oC. In spray dryers, the requirement for a high-feed moisture content to enable the evaporated milk to be pumped to the atomiser, can result in a higher loss of volatiles with the outlet air containing powder. This can give rise to emissions of VOC compounds and particulate material.
Water:
Wastewaters from cleaning and wet scrubber systems.
Land:
Deposition of particulate if air emission abatement is in adequate.
Waste:
Residues arising from cleaning of equipment or dust trapped in cyclones or bag filters. Both arisings can either be recycled or reworked for animal feed.
Energy:
For evaporation of water theoretically 2.2 MJ/kg is required. Due to energy losses in the process in practice the energy consumption for water evaporation (drying) ranges from 2.5 to 3.5 MJ/kg. Spray dryers are large-scale continuous process units with high energy costs. Steam dryers can have a considerably lower energy consumption.
Accidents:
Failure of air emission abatement.
Noise:
Not applicable.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Indicative BAT requirements for drying: 1
The main control issues are: • emissions to air – see Section 2.8 on page 90 – Typically exhaust air is passed through cyclones, however, the outlet air of cyclones may contain dust particles up to 200 mg/m3 which wil require secondary abatement, for example, fabric filters. • odour – see Section 2.8 on page 90 • energy efficiency – see Section 2.8 on page 90
2
Various measures typically used to reduce heat losses and save energy can be implemented for drying systems. These include: • recirculation of exhaust air to heat inlet air; • use of direct flame heating by natural gas and low NOx burners; • two-stage drying, for example fluidised beds followed by spray drying followed by fluidised beds; • pre concentrating liquid foods using multiple effect evaporation.
3
No further issues are identified.
2.1.6 Centrifugation and Bactofugation Summary of the activities
Centrifugation is used to separate immiscible liquids and solids from liquids by the application of centrifugal forces. Centrifugation is typically found in the dairy industry for clarification of milk, skimming of milk and whey, concentration of cream, butter oil production, production and recovery of casein, and in the cheese industry, lactose and whey protein processing, etc. Bactofuge treatment is a method of removing undesirable micro-organisms mechanically in a specially designed high-speed centrifuge, called a bactofuge or clarifier. Centrifugation is used to separate mixtures of two or more phases, one of, which is continuous. The driving force for separation is the difference in density between the phases. By using centrifugal forces the separation process is strongly accelerated. Centrifuges need to desludge solid material that builds up in the separating disks to maintain performance and milk quality. This “separator desludge” has a very high COD (c. 100,000 mg/l) and normally takes place every 30 to 60 minutes depending on conditions. Based on surveys completed, separator desludge often accounts for around 10 to 20% of the dairy factory total effluent loading, and is suitable for collection for separate disposal rather than discharge to effluent. When the differences in density are large and time is not a limiting factor separation can take place by gravity (known as sedimentation and skimming).
Environmental impact Air:
Not applicable.
Water:
Cleaning.
Land:
No direct impacts, unless separator desludge is discharged to land
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Waste:
Separator desludge has a very high COD and requires careful consideration for treatment and disposal
Energy:
Centrifuges consume relatively high levels of electricity.
Accidents:
Not applicable.
Noise:
The operation of centrifuges produce relatively high levels of noise in close proximity of the machines and suitable control measures need to be put in place.
Indicative BAT requirements for centrifugation and bactofugation: 1
The main control issues are: • energy efficiency – see Section 2.8 on page 90 • consideration required for the treatment and disposal of separator desludge – see Section 2.1.16 on page 36 • noise – see Section 2.1.16 on page 36
2
No further issues are identified.
2.1.7 Membrane Separation Summary of the activities
Membrane separation aims at selective removal of water (and solutes) from a solution by using semipermeable membranes. So it can also be seen as a fractionation technique. We can distinguish membrane filtration and electro dialysis; both are membrane separation techniques. Membrane separation can be applied for the concentration of liquids (for example cheese whey), the removal of solutes (for example de-mineralisation of whey), and for splitting a liquid into its components (for example whey fractionation). Membrane separation is also widely used for water purification, particularly in the middle-East. Membrane filtration is a pressure driven filtration technique in which a solution is forced through a porous membrane. Some of the dissolved solids are held back because their molecular size is too large to allow them to pass through and this is dependent upon the pore size and type of membrane used. Fractionation of the feed stream occurs with some molecules being concentrated on the upstream side of the membrane which is known as the concentrate or retentate, while the smaller molecules pass through the membrane into the permeate stream. The various membrane filtration techniques for example used in milk component fractionation can be characterised by their membrane pore size (the size of the smallest particle that cannot pass through the membrane): •
Micro Filtration (MF) pore size range 0.1 µm to 5 µm can be used to remove bacteria from skim milk during the production of ultra clean milks, or for fractionation skim milk into a casein rich retentate and a milk serum devoid of casein;
•
Ultrafiltration (UF) pore size range 10 - 100 nm and is applied to both skim milk and whey with the objective of concentrating the respective protein components.
•
Nanofiltration (NF) pore size range 1 - 10 nm with selective permeability for minerals, and are used predominantly for concentration and pre-demineralisation of whey.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
•
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Reverse Osmosis (RO) pore size range 0.1 - 1 nm membranes are permeable to water and not minerals and are therefore used for de watering, concentration of whey or skim milk, polishing UF or NF permeates and recovery of condensate (for example dairy evaporator condensate).
Electro dialysis (ED) is membrane separation in the presence of an applied electro potential. In electro dialysis, low molecular weight ions migrate in an electrical field across cationic or anionic membranes, these membranes being arranged in an alternate manner between the cathode and anode within a stack. Principle application within the dairy industry is for demineralisation of whey. Environmental impact Air:
Not applicable.
Water:
Handling of permeate (if not used as a by-product), and cleaning.
Land:
No direct impacts.
Waste:
No direct impacts.
Energy:
Membrane separation is a pressure driven process, electrical energy is required. In electro dialysis electrical energy is also required for the transporting of ions.
Accidents:
Consideration should be given to membrane failure and how to monitor the process.
Noise:
Not applicable.
Indicative BAT requirements for membrane separation: 1
The main control issues are: • waste water treatment – see Section 2.8 on page 90 • waste handling and disposal – see Section 2.1.16 on page 36 • energy efficiency – see Section 2.1.16 on page 36
2
No further issues are identified.
2.1.8 Ion Exchange Summary of the activities
Ion exchange is used to replace unwanted ions by passing the product through a resin bed of porous material with ions with the same charge as those to be exchanged. During the passage through the bed the ions are replaced and the resin bed picks up the unwanted ions, which then require recharging when the absorbing capacity has been depleted. The process is used within the dairy industry primarily for the demineralisation of whey, i.e. the removal of sodium and chloride ions to give a more valuable whey protein product, suitable for infant feeding, etc. The process requires a cation and anion exchange bed, both of which must be regenerated with concentrated acids and alkalis, producing heavily acidic and caustic effluent streams. Counter-current regeneration is often used for regeneration of the cation exchanger. This means that, when treating whey in the down-flow direction, the regeneration is carried out in the up-flow mode. This counter-current system reduces the consumption of the regeneration chemicals by as much as 3040%, and simply requires a change in construction of the resin tanks to allow the resin bed to expand in both directions.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Environmental impact Air:
Not applicable.
Water:
Cleaning and regenerating the resin beds requires large amounts of acids and alkalis and water.
Land:
No direct impacts.
Waste:
Produces very acidic and alkaline waste streams, which require consideration for disposal to effluent.
Energy:
Electrical energy input for pumps etc..
Accidents:
Spillage and/or of concentrated acid and alkalis and impact on sewer or treatment system..
Noise:
Not applicable.
Indicative BAT requirements for ion exchange: 1
The main control issues are: • cleaning techniques – see Section 2.8 on page 90 • emissions to effluent require careful consideration – see Section 2.1.16 on page 36
2
No further issues are identified.
2.1.9 Filtration Summary of the activities
Filtration is used in the food and drink industry to fulfil the following functions: •
to clarify liquid products by the removal of small amounts of solid particles (e.g. wine, beer oils and syrups). The filtrate is the objective of the operation;
•
to separate solid particles from either a liquid or air stream to avoid contamination (e.g. coarse inline filters on milk pasteuriser systems, or bag filters on milk powder dryers).
Filtration equipment operates either by the simple physical containment, or application of pressure (pressure filtration) to the feed side or by the application of a vacuum (vacuum filtration) to the filtrate side. Environmental impact Air:
The air discharge from the vacuum pump.
Water:
Depending on the purposes of the filtration operation the process may result in a liquid waste system.
Land:
No direct impacts.
Waste:
A filter residue may be produced which will require a suitable method of recovery or disposal, e.g. solids from bag filters.
Energy:
Required for application of pressure or vacuum..
Accidents:
Not applicable.
Noise:
Not applicable.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Indicative BAT requirements for filtration: 1
The main control issues are: • waste water treatment – see Section 2.8 on page 90 • waste handling and disposal – see Section 2.8 on page 90 • energy efficiency – see Section 2.1.16 on page 36
2
No further issues are identified.
2.1.10 Churning Summary of the activities
Churning is the process used in buttermaking after the crystallisation of the fat globules, and is now carried out in cylindrical, conical or tetrahedral churns with adjustable speed settings, that permit a speed selection for any given butter requirement. The fat globules in butter cream contain both crystallised and liquid fat, which when agitated produce butter grains, the precursors to the butter which is separated from the buttermilk. The amount of fat left in the buttermilk gives a measure of the churning recovery, and is typically around 0.5 to 0.7%. This shows that, for example if the churning recovery is 0.5%, only 0.5% of the cream fat has remained in the buttermilk. Working the butter takes place in another section of the continuous buttermaker, after the buttermilk has been drained off. The fat globules are subjected to a high pressure and liquid fat and fat crystals are forced out. In the resulting mass of fat, the moisture becomes finely dispersed, and is prevented from coalescing. In the modern buttermaker, the finished butter is discharged as a ribbon from the end nozzle into a butter trolley or silo for further transport to the packing machines. Due to its high fat content (c. 80%), butter has a very high COD (c. >2,400,000mg/l), and even buttermilk has a COD of around 100,000mg/l, so care has to be taken to avoid loss to effluent. Modern cleaning techniques use steam to melt out the residual butter prior to cleaning, with this melt-out used as re-work during the next production run. Fat losses in effluent streams from buttermaking dairies require consideration when evaluating effluent treatment and disposal options.
Environmental impact Air:
Not applicable.
Water:
Water is used and effluent generated during cleaning, often with high FOG (fats, oils and grease) concentrations.
Land:
No direct impacts.
Waste:
Melt-out can be reused.
Energy:
Normal requirements for electrical motors etc..
Accidents:
Could be problems with spillage of buttermilk, as a less valuable by-product.
Noise:
Not applicable.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Indicative BAT requirements for churning: 1
The main control issues are: • cleaning techniques – see Section 2.8 on page 90 • emissions to effluent require consideration, particularly for fat losses – see Section 2.8 on page 90 • energy efficiency – see Section 2.1.16 on page 36
2
No further issues are identified.
2.1.11 Cooling and Chilling Summary of the activities
The objective of cooling and chilling is to reduce the rate of biochemical and microbiological changes, in order to extend the shelf life of fresh and processed milk and milk products. Cooling can be defined as the processing technique that is used to reduce the temperature of the food from processing temperature to storage temperature. Chilling is the processing technique in which the temperature is kept between –1oC and 8oC. As the shelf life of fresh milk and milk products is relatively short, most dairies have a great demand for refrigeration plant and this can represent a significant item in the budget of any dairy. Typically the cooling of liquid milk and milk products is carried out by passing them through a heat exchanger (cooler). The cooling medium in the cooler can be mains or borehole water, water recirculating over a cooling tower or water (eventually mixed with agents like glycol) which is recirculated via a mechanical refrigeration system (ice-water). The cooling process is usually a closed circuit in which the refrigerant is changed from gaseous to liquid form by reducing the pressure (expansion) and by increasing the pressure (compression) respectively. In cryogenic cooling the food is in direct contact with the refrigerant, which can be solid or liquid carbon dioxide, liquid nitrogen or a liquid freon. The refrigerant evaporates or sublimates removing the heat from the food causing rapid cooling.
Environmental impact Air:
Fugitive emissions of refrigerants, ammonia, freon etc.
Water:
‘Once-through’ cooling post heat treatment requires substantial quantities of cooling water..
Land:
No direct impacts.
Waste:
Not applicable.
Energy:
Mechanical refrigeration systems demand substantial amounts of electrical energy.
Accidents:
Spillages and leaks of refrigerants, especially ammonia have caused some notable major pollution incidents in dairy installations.
Noise:
Refrigeration compressors produce high noise levels in close proximity to the machines and suitable control measures need to be put in place.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Indicative BAT requirements for cooling and chilling: 1
The main control issues are: • water use – see Section 2.8 on page 90 – The operator should justify why the re-use of ‘once through cooling’ waters is not possible. • cleaning techniques – see Section 2.8 on page 90 • fugitive emissions to air and water (refrigerants) – see Section 2.1.16 on page 36, detailed drainage plans are required to ensure that ammonia leaks cannot be discharged to surface waters • energy efficiency – see Section 2.1.16 on page 36
2
No further issues are identified.
2.1.12 Freezing and Blast Cooling Freezing is a method for preservation, where the temperature of a food is reduced below the freezing point and a proportion of the water undergoes a change in state to form ice crystals. Many types of food can be frozen for example, fruits, vegetables, fish, meat, baked goods and prepared foods. In addition both dairy and non-dairy ice cream is also frozen, often by means of continuous freezer units which whip a controlled amount of air into the ice cream mix and freeze the water into a large number of small ice crystals. During the freezing process “sensible” heat is first removed to lower the temperature of the food to the freezing point (in fresh foods this includes heat produced by respiration). Latent heat of crystallisation is then removed and ice crystals are formed. A whole range of methods and equipment for freezing foods is available. Most common are: •
Blast freezers,
•
Belt freezers (spiral freezers),
•
Fluidised-bed freezers,
•
Cooled surface freezers,
•
Immersion freezers,
•
ryogenci freezers.
Environmental impact Air:
Fugitive emissions of refrigerant.
Water:
Not applicable.
Land:
No direct impacts.
Waste:
Not applicable.
Energy:
Mechanical refrigeration systems demand substantial amounts of electrical energy.
Accidents:
Spillages and leaks of refrigerants, especially ammonia have caused some notable major pollution incidents in dairy installations.
Noise:
Compressor noise from larger units.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Indicative BAT requirements for freezing and blast cooling: 1
The main control issues are: • fugitive emissions to air and water (refrigerants) – see Section 2.1.16 on page 36, detailed drainage plans are required to ensure that ammonia leaks cannot be discharged to surface waters • energy efficiency – see Section 2.1.16 on page 36
2
No further issues are identified.
2.1.13 Mixing, Blending and Homogenisation Summary of the activities
The aim of this group of operations is to obtain a uniform mixture from two or more components or to obtain an even particle size distribution in a food material. This may result in improved characteristics and eating quality. These are widely applied in almost all sectors in the food industry. Mixing (blending) is the combination of different materials and their spatial distribution until a certain degree of homogeneity is achieved. In the food industry various mixing operations can be distinguished. Solid/solid mixing is encountered for mixed feed, blends of tea and coffee, dried soup, cake mixes, custard, ice cream mixes, etc. Solid/liquid mixing is applied for canned goods, dough, dairy products, etc. Solid/liquid mixing is also applied for the production of chocolates and sweets; the ingredients are mixed in a more or less liquid state and solidify on cooling. Liquid/liquid mixing is applied for making emulsions like mayonnaise, margarine and mixtures of solutions. Liquid/gas mixing is used in making ice cream, whipping cream, some sweets and baked goods. Commonly applied mixers for solid/solid mixing are rotating drums, other rotary mixers and mixing screws in cylindrical or cone-shaped vessels. For viscous solid/liquid and mixing kneading machines are used. For low viscous solid/liquid mixtures and liquid/liquid mixtures various types of stirrers, impellers and agitators are applied. In making ice cream, whipped cream or stable foams, small gas bubbles are brought into a liquid using a variety of methods. The tendency of milk fat to float in milk and form a creamline on the surface makes it possible to separate fat from milk. In the manufacture of certain dairy products, however, this is undesirable, and homogenisation of the milk can prevent this occurring. Homogenisation is a process whereby the fat globules in milk are subjected to mechanical treatment which breaks them down into smaller globules, uniformly distributed. Homogenisation usually takes place under high pressure (100 to 200 bar) by passing the milk through a very small orifice
Environmental impact Air:
Odour in those operations in where volatile compounds are involved. Particulates (dust) can be formed in operations in which solids or powders are involved.
Water:
Cleaning and used for homogeniser cooling water.
Land:
No direct impacts.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Waste:
Product removed by cleaning.
Energy:
Some of the operations of this group require a substantial energy input.
Accidents:
Not applicable..
Noise:
Not applicable.
Indicative BAT requirements for mixing, blending and homogenisation: 1
The main control issues are: • cleaning techniques – see Section 2.1.16 on page 36 • emissions to air (dust and odour) – see Section 2.1.16 on page 36
2 Summary of the activities
No further issues are identified.
Forming, moulding and extruding are operations for attaining a certain shape of solid or semi-solids materials. Forming/moulding is an operation widely applied for the production of bread, biscuits, confectionery and pies. In cheese making, moulding and pressing is also an important process step to ensure the correct texture of the cheese, and allow residual whey to drain off In forming/moulding the material is brought in a more or less viscous form in the moulds, with subsequent material becoming firmer and solid up to the point that is has a fixed shape. Extrusion is widely used for the production of meat sausages, pasta products such as macaroni, vermicelli and spaghetti, but also for a lot of other products like confectionery and dairy and non-dairy ice-creams. Extrusion can be seen as a continuous process of shaping. The material is kneaded under high pressure and pressed continuously through openings of the required shape. In so-called cooking extruders the material is also heat treated (cooked), for example to solubilise starches. Extruders can contain one or two screws. The rotation of the screws is responsible for the transport of the material, mechanical treatment and pressure built-up.
Environmental impact Air:
Odour from extrusion cooking arising from extruder vents as moisture is flashed off as steam.
Water:
Water is used and effluent generated during cleaning of equipment. Whey released from cheese moulds and presses has a very high COD (c. 60 to 80 000mg/l) and this requires collection rather than disposal to effluent.
Land:
No direct impacts.
Waste:
Some solid waste may be generated due to loss of product at the start and finish of the production process.
Energy:
Extruders show typically high power consumption.
Accidents:
Spillage of whey can seriously overload effluent treatment systems.
Noise:
Not applicable.
Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Techniques for pollution control Techniques
Introduction The Themain main activities activitiesand and abatement abatement
Abatement of point source emissions
Management techniques
Raw materials
Waste handling
Emissions Waste recovery or disposal
Energy
Impact Accidents
Noise
Monitoring
Closure
Installation issues
Indicative BAT requirements for forming, moulding and extrusion: 1
The main control issues are: • cleaning techniques – see Section 2.1.16 on page 36 • emergency planning for dealing with whey spillages – see Section 2.1.16 on page 36 • emissions to air (dust and odour) – see Section 2.1.16 on page 36
2
No further issues are identified.
2.1.14 Filling Summary of the activities
Once the finished products are made they are then put into suitable packages for direct sale to the public or retail outlet. The final product package plays an important part in the sales and marketing of the product, particularly in the dairy industry. The package must sell the product, be convenient, easy to open, pleasant to handle, as well as protect and maintain the quality of the product. Glass bottle filling for milk was introduced at the beginning of the 1900’s, and is still used today, despite the weight and need for cleaning the returned bottles before re-use. With the advert of plastic paper laminates and thermoplastics in the 1960’s, however, the proportion of milk sold in glass bottles has steadily declined. There are a large variety of companies supplying filling machines for dairy products, along with a variety of formats. Consideration should be given to water requirements of the machine, both in use and during cleaning, along with any systems for the separate collection of high strength purges or interfaces that are produced during start-up and shut-down.
Environmental impact Air:
Not applicable.
Water:
Water is used and effluent generated during cleaning of filling equipment.
Land:
No direct impacts.
Waste:
Some solid waste may be generated due to loss of product at the start and finish of the production process.
Energy:
Fillers can show relatively high power consumption.
Accidents:
Spillage of products can seriously overload effluent treatment systems.
Noise:
Some high-speed fillers (especially with glass bottles) are noisy and require abatement measures to be adopted.
Indicative BAT requirements for filling: 1
The main control issues are: • cleaning techniques – see Section 2.1.16 on page 36 • emergency planning for dealing with product spillages – see Section 2.1.16 on page 36 • emissions to air (dust and odour) – see Section 2.1.16 on page 36
2
No further issues are identified.
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2.1.15 Fermentation/Incubation Process Summary of the activities
Fermentation processes are used in the production of yoghurt, kefir and other cultured milk products. These use bacterial cultures under controlled conditions, which results in fermentation of the milk substrate to give the cultured product its characteristic properties, such as acidity, flavour, aroma, and consistency. Cultured dairy products have different characteristics and different starter cultures are therefore used in their manufacture. Commercial starter cultures are available in liquid, freeze-dried, or frozen formats, and are usually progagated in the dairy for production use. Starter manufacture is one of the most difficult processes in the dairy, and problems can result in loss of production, so the highest standards of hygiene are required. The risk of airborne infection by yeasts, moulds and bacteriophages must be eliminated, and therefore most starter culture rooms are provided with sterile air at higher pressure than the surrounding areas. The starter cultures are inoculated into the milk substrate and incubation or fermentation begins. The incubation time is determined by the types of bacteria in the culture, and can vary from 3 to 20 hours. When the product has reached the correct acidity it is cooled, to prevent further fermentation, and then packed. For yoghurt production, there are three main types: •
Set-type, which is filled immediately after inoculation with the bulk starter, with the incubation taking place in the pot
•
Stirred-type, which is inoculated and incubated in a tank, with the product cooled before packing
•
Drink-type, which is similar to the stirred-type yoghurt but with the coagulum being broken down to a liquid prior to filling
Similar processes are used for the manufacture of kefir and cultured cream. The cultured milk product produced in these fermentation reactions is often a viscous, sometimes semi-solid material, with a high COD content (c. 200 to 400,000mg/l), so any spillages to effluent can have an impact on effluent treatment processes. Environmental impact Air:
Not applicable.
Water:
Water is used and effluent generated during cleaning of fermentation vessels.
Land:
No direct impacts.
Waste:
Some solid waste may be generated due to loss of product at the start and finish of the production process.
Energy:
No direct impacts.
Accidents:
Spillage of products can seriously overload effluent treatment systems.
Noise:
Not applicable.
Indicative BAT requirements for fermentation/incubation processes: 1
The main control issues are: • cleaning techniques – see Section 2.1.16 on page 36 • emergency planning for dealing with product spillages – see Section 2.1.16 on page 36 • emissions to air (dust and odour) – see Section 2.1.16 on page 36
2
No further issues are identified.
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Monitoring
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2.1.16 Cleaning and sanitation Summary of the activities
The thorough cleaning and disinfection of equipment is absolutely essential in a dairy factory, since poor hygiene can have disastrous consequences for product quality. With the nature of dairy operations changing over the years, there has been a decline in small units with manual operation and an increase in larger units with factory-style production techniques. Cleaning and sanitation can be carried out in various ways: •
manually
•
cleaning-in-place (CIP)
•
high-pressure jet cleaning
•
foam cleaning
Manual cleaning means that the equipment to be cleaned is taken apart and manually cleaned (brushed) in a cleaning solution. Only mild conditions, with regard to temperature and cleaning agents, can be used. Cleaning in place (CIP) was pioneered in the dairy industry in the 1950’s and is used for closed process equipment and tanks. The cleaning solution is pumped through the pipelines and equipment and is distributed within tanks and vessels by spray-balls or spray turbines, which vigorously blast the surfaces with the cleaning solution. The cleaning programme is mostly run automatically. The following steps can be distinguished: •
pre-rinse with water,
•
circulation with a cleaning solution,
•
intermediate rinse,
•
disinfection,
•
final rinse with water.
In modern automatic CIP-systems the final rinse water is often recirculated and used for pre-rinsing. Furthermore, it is possible to combine the disinfection stage with the final rinse. In CIP-cleaning high temperatures (up to 90oC) are used and strong cleaning agents. CIP systems can be much more efficient than manual cleaning but should be designed and used with due consideration to wastewater minimisation, since experience shows that CIP systems use much more water than manual cleaning techniques. In modern, large-scale dairy plants about half of all the effluent loading (both volumetric and organic, kgCOD) from the factory comes from CIP operations, so it pays to ensure that these systems are fully optimised with regard to water usage and product loss. On most CIP cleans, the pre-rinse stage of the sequence contains the most product loss, so this can be examined in detail to build a picture of product wastage from each CIP pre-rinse operation. Samples of the pre-rinse can be taken every 5-15 seconds. (See Ref. 6 under waste minimisation references). From this a programme can be designed to optimise CIP programmes and ensure minimal losses and efficient cleaning. The programme produces graphs (see following page), from which the efficiency of the CIP can be evaluated from an effluent viewpoint. The CIP-PROP graph on the following page shows that there is a total loss to effluent of nearly 96 litres of milk in this pre-rinse, and about half of this is present in the first 10 seconds of the sequence, indicating the need for better draining or purging of the silo prior to cleaning. In addition, it can be seen that the pre-rinse cycle extends for a total of 130 seconds, despite the fact that after around 70 seconds there is no more product contamination in the wastewater. This means that water savings are possible by trimming the pre-rinse cycle timing by around 50 seconds, saving around 400 litres of water per
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clean. These observations would need checking to establish repeatability but highlight that careful examination of CIP sequences can give substantial savings in product loss (and hence environmental impact) and water usage. Furthermore, with the advent of increased automation in dairy operations in general, and in CIP systems in particular, it often pays to conduct environmental impact, or wastage surveys of product loss and water usage on CIP systems. In most cases, these systems are set up by the contractors to ensure proper cleaning and maintenance of product quality as the primary objective, with water usage and product loss much further down the hierarchy of needs. Wastage minimisation surveys usually find significant product, water and financial savings by examining CIP systems in detail. Also, during CIP plant design, the process contractors are skilled in meeting the various demands imposed by the dairy company, and it pays to ask them to focus on the environmental impact of the operations, by asking specific questions regarding water usage and product loss. The exact design of a CIP system is determined by a variety of factors, including: •
how many individual CIP circuits are to the served by each CIP station? How many require hot rinses and how many require cold rinses?
•
Are the initial milk/product rinses collected? Will they be processed (evaporated), or collected for animal feed?
•
What method of disinfection will be used? Chemicals, steam or hot water?
•
What is the estimated product loss, steam, and water demand of each cleaning operation?
It therefore pays to get a thorough understanding of the environmental impacts of the CIP system at the design stage, so that modifications can be made before the system is installed, rather than have to spend time and effort trying to optimize the system after installation, when it will be in full use. In high-pressure jet-cleaning, water is sprayed at the surface to be cleaned at a pressure of about 40 to 65 bar. Cleaning agents are injected in the water, and moderate temperatures up to 60 ×C are used. An important part of the cleaning action is due to mechanical effects. Pressure washing reduces water and chemical consumption compared with mains water hoses. It is important, however, that a pressure that is both safe and efficient is used. There is some concern in the food and dairy industry about the hygiene implications of over-splash and aerosols associated with the use of high-pressure hoses, and this type of cleaning is sometimes therefore restricted to areas outside the main production areas. In foam cleaning, a foaming cleaning solution is sprayed on the surface to be cleaned. The foam adheres to the surface. It stays about 10 to 20 minutes on the surface and is then rinsed away with water. High-pressure jet cleaning and foam cleaning is generally applied for open equipment, walls and floors. It is common practice for staff involved in clean-up operations to remove floor-drain grates and flush raw materials and product directly down the drain, believing that a subsequent screen or catch pot will trap all solids. However, when these materials enter the wastewater stream they are subjected to turbulence, pumping and mechanical screening. This results in the break down and release of soluble BOD, along with colloidal and possibly suspended grease solids. Subsequent removal of this soluble, colloidal and suspended organic matter can be far more complicated and expensive than the use of simple screens. In all cases, this practice should be strongly discouraged as it engenders the wrong attitude in factory staff. Cleaning agents that are used in food and drink industry are alkalis (sodium and potassium hydroxide, metasilicate, sodium carbonate), acids (nitric acid, phosphoric acid, citric acid, gluconic acid) composed cleaning agents containing chelating agents (EDTA, NTA, phosphates, polyphosphates, phosphonates) and surface-active agents. Sanitation chemicals and techniques Oxidising biocides oxidise the bacterial cell walls in order to prevent replication. They rely on the use of strong oxidising agents such as chlorine/bromine, ozone and hydrogen peroxide. The use of chlorine compounds (chlorine gas, chlorine dioxide, sodium hypochlorite) relies upon the formation of
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hypochlorous acid (the active biocide) in aqueous solution. Bromine-based biocides are also becoming more prevalent in industrial applications due to the hypobromous acid species dissociating at a higher pH than the equivalent chlorine-based compounds. The main disadvantage of chlorine-based chemistry is the ability of chlorine to react with a wide number of other compounds and so actually reduce the “effective” chlorine dose rate. The use of ozone is also increasing for disinfecting purposes. Non-oxidising biocides operate by chemically altering the cell structure in order to prevent bacterial cell replication. These are becoming common, and examples are quaternary ammonium salts and formaldehyde/glutaraldehyde. UV light is perhaps the most significant advancement in disinfection technology over the past 10 years. UV light at 254 nm is readily absorbed by the cellular genetic material within bacteria and viruses, which prevents the cell from replicating. The main advantages of UV disinfection over other techniques include no storage or use of dangerous chemicals, the absence of harmful by-products (no organohalogens) and is a simple technology with relatively low capital and operating costs. The dose rate is measured in milliwatts per square centimetre multiplied by the contact time in seconds. The actual dose is dependent on the transmittance (i.e. compounds which can absorb and reduce UV light effectiveness) of the wastewater stream. UV light also causes an immediate reaction and therefore does not impart any residual effect, with treated waters liable to re-infection. The main disadvantage of UV disinfection is that a direct line of sight must be maintained between the lamp and the bacteria/virus. Any appreciable levels of suspended solids (hence decreasing transmissivity) will actually shield the bacteria and prevent their disinfection. Environmental Impact
Air: Not applicable. Water: Wash waters will contain remnants of cleaning agents, product rinsed from the system and removed from the equipment that is cleaned. Land: No direct impacts. Waste: Not applicable. Energy: Cleaning is commonly carried out at elevated temperatures utilising steam. Pre-clean systems, for example vacuum transfer, blowers and pigging systems, require power and compressed air. Accidents: Spillage of cleaning chemicals. Leakage from effluent system. Overloading of effluent treatment system. Noise: Not applicable.
Indicative BAT requirements for cleaning and sanitation: (Sheet 1 of 3) 1
The single most important factor in reducing wastewater strength in this sector is the adoption of dry clean-up techniques. Wherever possible raw materials and product should be kept out of the wastewater system. EXAMPLE Dairy sector Treating spills of curd, yoghurt or ice cream mix as solid waste rather than washing them down the drain.
2
Taking this as the starting point, the Operator should demonstrate that procedures are in place to achieve this and then ensure that appropriate cleaning procedures are in place and should include such measures as the following:
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Indicative BAT requirements for cleaning and sanitation: (Sheet 2 of 3) 3
Equipment design: • wherever practicable, process lines and operations that cause excessive spillage of material onto the floor should be modified to eliminate or reduce the problem (ETBPP GG154 – Ref. 8) • removing as much residual material as possible from vessels and equipment before they are washed • ensuring that drains are equipped with catchpots • that the catchpots are in place during cleaning (for example by installing lockable catchpots); • optimisation of water pressure at jets, nozzles and orifices • automatic water supply shut off on trigger operated spray guns or hoses
4
Good housekeeping: • installing trays to collect waste as it falls to the floor • sweeping, shovelling or vacuuming spilt material rather than hosing it down the drain • making sure suitable dry clean-up equipment is always readily available • providing convenient, secure receptacles for the collected waste • optimisation of cleaning schedules • matching cleaning cycle durations to the vessel size • product scheduling to minimise numbers of product changes and subsequently cleaning between products
5
Management of manual cleaning: • procedures to ensure that hoses are only used after dry clean-up • trigger controls should be used on hand-held hoses and water lances to minimise the use of washdown water • use of high-pressure/low-volume systems
6
Cleaning chemicals usage: • The Operator should ensure that staff (and contract cleaners) are trained in the handling, making up and application of working solutions, for example, not setting the concentration of the chemical agent too high and avoiding the overuse of chemicals, particularly where manual dosing is used.
7
Cleaning-in-place (CIP): • dry product removal before the start of the wash cycle by gravity draining, pigging or air blowdown • pre-rinse to enable remaining product to be recovered for re-use or disposal • use of in-line turbidity or conductivity detectors to maximise product recovery and isolate product/water interface – for example conductivity sensors can be used to monitor levels of dissolved salts, and hence product contamination in CIP systems, to provide for automatic collection of milk:water interfaces for re-processing. – turbidity sensors can also be used to monitor the quality of process water and CIP systems and will therefore minimise effluent from out-of-specification products/process water and optimise re-use of cleaning water respectively. • optimal CIP programme for the size of plant/vessel and type of soiling • automatic dosing of chemicals at correct concentrations • internal recycling of water and chemicals • recycle control on conductivity rather than time • continuous cleaning of recirculated solutions • water-efficient spray devices
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Indicative BAT requirements for cleaning and sanitation: (Sheet 3 of 3) 8
Sanitisation: • the Operator should justify the use of organohalogen-based oxidising biocides over the alternatives, for example ozone and UV light
9
Recycling of water and recovery of cleaning chemicals – see Section 2.4.2.1 on page 75.
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2.2 Abatement of point source emissions
2.2.1 Abatement of point source emissions to air Nature of the emissions
The nature and source of the emissions expected from each activity is given in previous sections and the inventory of emissions should be confirmed in detail in the Application. Activity
Pollutant VOC
Odour
Particulate
SOx, NOx,
aterials handling of liquid milk and milk products(section 2.3.1) Heat Processing Pasteurisation, sterilisation and UHT Evaporation Drying Separation and Concentration Filtration Processing by the Removal of Heat Cooling and chilling Freezing and blast cooling Other Dairy Processes Mixing, blending and homogenisation Boilers and Combustion plant Effluent treatment systems The distinction between emissions of VOC/odour and particulate/odour are not always clear. Where odour (see Section 2.2.6 on page 67) may be an issue, the cause will typically be emissions of VOCs (sometimes at low concentrations). Measures taken to prevent or reduce VOCs might also lead to a reduction in odour and similarly for particulate.
Indicative BAT requirements for control of point source emissions to air: (Sheet 1 of 3) 1
The benchmark values for point source emissions to air listed in Section 3.2.1 on page 108 should be achieved unless alternative values are justified and agreed with the Regulator.
2
The main chemical constituents of the emissions should be identified, including VOC speciation where practicable.
3
Vent and chimney heights should be assessed for dispersion capability and an assessment made of the fate of the substances emitted to the environment (see Section 4 on page 123).
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Indicative BAT requirements for control of point source emissions to air: (Sheet 2 of 3) Control of visible particulate plumes 4
Even where particulate benchmarks are already met, the aim should be to avoid visible emissions. However, because plume visibility is extremely dependent on the particle size and reflectivity, the angle of the light, and the sky background, it is accepted that, even when BAT is employed and very low emissions are being achieved, some plumes may still be visible under particular conditions. Control of visible condensed water plumes
5
The need to minimise water vapour plumes should always be considered as, in addition to possible local visual amenity issues, in severe cases, plumes can cause loss of light, fogging, icing of roads, etc. High moisture content can also adversely affect plume dispersion so, where practicable, water content of the exhaust stream should be reduced. Ideally, the exhaust should be discharged at conditions of temperature and moisture content that avoid saturation under a wide range of meteorological conditions, including cold damp conditions.
6
The use of primary energy to reduce a plume simply because it is visible is not considered BAT. However, it may be appropriate to use waste or recovered heat, for example, heat in a gas stream prior to wet scrubbing can be used for re-heating the exhaust stream after scrubbing by means of a gas-gas heat exchanger. The use of energy for exhaust gas re-heat should be balanced against the benefits gained.
7
The Operator should provide the identification of the main chemical constituents of the emissions (particularly for mixtures of VOCs) and assessment of the fate of these chemicals in the environment (refer to Section 2.2.6 on page 67, Odour – identification of constituent components may not always be practicable for VOCs where concentrations are low).
8
Air movements around loading/unloading and transfer points for dry powders and grain, etc., are a significant source of dust emissions. Orientation of the plant and installation of roll down or bi-fold doors should reduce wind effects.
9
Enclosure
10
Generally, the volume of air involved determines the degree of difficulty in dealing with air emissions. The volume of air has implications not only for the final size of abatement plant but also for the associated equipment such as fans, ducting, pressure losses, etc. Optimum containment of odorous or polluted air is therefore important in either eliminating the need to treat the air or minimising the amount (and consequently cost) of the abatement technology. Enclosure of specific units identified as being a source of pollution should be implemented to reduce air volumes requiring abatement (see Figure 12 and Figure 13).
11
The Operator should maintain a plan for the reduction of emissions to air, in particular odourous VOCs, combustion gases and particulates. The plan should be revised annually and submitted to the regulator.
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Indicative BAT requirements for control of point source emissions to air: (Sheet 3 of 3) 12
Example of enclosure of a food processing unit
Exhaust Detachable cover
13
Auger conveyor
Example of enclosure of a conveyor system (also see Section 2.1.2 on page 20)
Conveyor Exhaust
Process unit, e.g. crusher
Access door
Conveyor Drain for washing effluent Processes using heat 14
Energy-efficient techniques, such as heat recovery systems on indirect fired ovens and fryers, utilise exhaust air for pre-heating and also recycle the exhaust gas to the heater. The combustion of the recycled exhaust gas should be considered as a technique for reducing NOx emissions in the release to atmosphere. Techniques for the Dairy sector
15
Air movements around loading/unloading and transfer points for dry powders, sugars, etc. are a significant source of dust emissions. Orientation of the plant and installation of roll down or bi-fold doors will reduce wind effects.
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Management techniques
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Monitoring
Closure
Installation issues
Table 2.2: Abatement options for specified pollutants
Activity
Abatement options for specified pollutants (Note 3) VOC
Odour
Receiving and handling of raw materials (Note 1) (Note 2)
Particulate
SOx, NOx,
Cy, FF
Preparation of raw materials Dry cleaning Peeling
Cy, FF C, TO, BO, CO
Mixing (of dry powders) Extrusion
Cy, FF C, TO, BO, CO
Heat processing using steam or water Blanching C, TO, BO, CO Evaporation
Cy, FF
Pasteurisation/sterilisation
Ad, C, TO, BO, CO
Heat processing using hot air Drying
C, TO, BO, CO
Baking and roasting
Cy, FF Ab, Ad, C, TO, BO, CO
See “Processes using heat” on page 43
Frying
Ab, Ad, C, TO, BO, CO
See “Processes using heat” on page 43
Grinding and milling Solvent extraction Effluent treatment systems
Cy, FF Ad, C, TO, BO, CO Ad, C, TO, BO, CO
Notes: 1. In addition to enclosure, emissions from conveyor systems should be prevented by minimising freefall distances and reducing velocities. 2. Gravity unloading of, for example, grain from the delivering vehicle to a bunker can give rise to significant dust emissions. Using a technique such as an enclosure or a choke flow system should be employed as appropriate to reduce these emissions. 3. See Table 2.3 for more information on abatement options. Key: Ab, Absorption; Ad, Adsorption; C, Condensation; TO, Thermal oxidation; BO, Biological oxidation; CO, Catalytic oxidation; Cy, Cyclones; FF, Fabric filters. Guidance for the Dairy and Milk Processing Sector IPPC S6.13 | Issue 1 | Modified on 26 October, 2003
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Table 2.3: Abatement options information
Key
Name
Comment
Ab
Absorption
Suitable for high-flow, low-concentration (1–200 mg/m3 VOC), low-temperature gas streams, where the pollutant is chemically reactive (or soluble in the case of VOC contaminants). A common use is the treatment of contaminated ventilation air. Water supply and effluent disposal facilities must be available.
Ad
Adsorption
The humid nature of many food waste streams counts against carbon adsorption as a technology because the polar nature of the common adsorbents will preferentially adsorb water vapour.
C
Condensation
Air streams from, for example, cookers and evaporators can contain volumes of water vapour, which are much greater than the volume of air and non-condensables. If the air stream is to be abated by thermal oxidation, the required energy to oxidise a wet stream containing 1 kg water/kg dry air (at 100°C) is approximately 2.6 times the energy requirement for the equivalent dry stream. Condensation is a useful pre-treatment, which, in addition to reducing the fuel requirement and the overall size of oxidiser, will also provide abatement.
TO
Thermal oxidation
For Food and Drink sector applications this will usually require the addition of supplementary fuel to support the combustion process. Even for VOC abatement purposes it is unlikely that any food applications will be autothermal. The Operator can offset the cost of the supplementary fuel when there is a requirement elsewhere on-site for the waste heat that is generated.
BO
Biological oxidation
Typically applied to air streams with VOC < 1500 mg/m3. Requires a long residence time, typically > 30 s. For a gas flow of 150,000 Nm3/h, a reactor volume of approximately 1250 m3 would be required. The available surface area may be the limiting factor. Variability in gas flow rate, gas composition in terms of available organic constituents, pH, temperature and humidity may be difficult to manage.
CO
Catalytic oxidation
Suitable for air flow range 150–70,000 m3/h. The catalyst has an upper temperature limit and an increase in VOC concentration may increase the temperature beyond the limit.
Cy
Cyclones
Relatively cheap and reliable. Not effective against particle sizes 7
guideline:
6
50%>9, 100%>5
* 50% median and 100% minimum standard.
Table 3.2: Biochemical oxygen demand: water quality objectives in Scotland
Water quality objectives
BOD (ATU)
Dissolved O2
Scotland
(mg/l, 90%ile)
(% saturation, 10%ile)
Class Excellent
80
Class Good
70
Class Fair
60
Class Poor
20
Class Seriously Polluted
>15
9
guideline
3
50%ile>9, 100%>7
Cyprinind imperative
-
50%ile>7
guideline
6
50%ile>9, 100%>5
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Biochemical oxygen demand
* 50% median and 100% minimum standard. Benchmark emission values The BOD benchmarks are obviously important where a treated effluent is being discharged to a watercourse. Such a benchmark is also an important measure where the effluent is to be treated off-site (see Section 2.2.5 on page 65) where the Operator has to assess the off-site treatment against what could be carried out on-site under BAT criteria. On-site biological treatment plant can be designed to deliver a concentration of 10–20 mg/l (flowweighted monthly average), for any incoming load. The mass release will therefore be determined by the water flow. Minimisation of water usage would therefore be important. Lower values can be achieved by filtration as secondary or tertiary treatment. For new plant discharging to controlled water, 10–20 mg/l represents BAT in the general case. Existing plant should be up-rated to meet at least the larger values in the ranges for the appropriate plant in the above table. In specific cases it may be possible to demonstrate that BAT does not require these levels. Such a case should be based upon: •
understanding of the chemical composition of the discharge, in particular the lack of persistent, bioaccumulative, or toxic elements which could have been removed by further treatment
•
a knowledge of the local environment and an assessment of the likely impact thereon
•
an appropriate environmental monitoring programme to demonstrate that there is no significant impact
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Chemical oxygen demand
3.4 Chemical oxygen demand Other applicable standards and obligations None. Benchmark emission values Not available. Emission limit values would normally only be set if the impact of the COD was understood and there is a clear reason for setting the limit such as to drive a reduction to an agreed plan, as a toxicity surrogate or where there are agreed actions which can be employed to control it. Thus it is more important that there is: •
an understanding of the chemical composition of the discharge, in particular the lack of persistent, bioaccumulative, or toxic elements which could have been removed by further treatment
•
a knowledge of the local environment and an assessment of the likely impact thereon
•
an appropriate environmental monitoring programme to demonstrate that there is no significant impact
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Halogens
3.5 Halogens Other applicable standards and obligations (Extracts from standards are quoted for ease of reference. The relevant standards should be consulted for the definitive requirements.) Table 3.3: Halogen standards
Total residual chlorine (as mg/l HOCl)
Designated freshwaters SI 1997/1331 Salmonid
imperative:
0.005
guideline: Cyprinid
-
imperative:
0.005
guideline:
-
Dangerous Substances List 1 (Fresh or tidal) Benchmark emission values Table 3.4: Benchmark emission values
Media
Substance
Activity
Benchmark value
To air
HCl and HF
Combustion/incineration
See appropriate Guidance
Basis for the benchmark
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Heavy metals
3.6 Heavy metals Other applicable standards and obligations (Extracts from standards are quoted for ease of reference. The relevant standards should be consulted for the definitive requirements.) Table 3.5: Heavy metal standards
Zinc and copper
Mercury
Cadmium
(µg (as metal)/l annual average) Designated freshwaters
Depends on water hardness – see Regulations and Note 1
SI 1997/1331 UK water quality objectives Dangerous Substances emission limits List 1 Fresh:
1.0
5
0.3
2.5
Coastal: Dangerous Substances emission limits List 2
Most metals – see Note 1
(Fresh or tidal) Note 1: Unless these metals are known to be used – from assessment of raw materials inventory or from a one-off analysis (see Section 2.10 on page 96), further monitoring or emission limit values are not normally required. Benchmark emission values Where sources of mercury or cadmium cannot be eliminated or reduced to the above by control at source, abatement will be required to control releases to water. In biological treatment 75–95% of these metals will transfer to the sludge. Levels are unlikely to cause problems for the disposal of sludge, but care will need to be taken to ensure that levels in the receiving water are acceptable. The figures below are achievable, if necessary, to meet water quality standards. Table 3.6: Heavy metal benchmark emission values
Media
Substance
Activity
Achievable levels if required
Basis for the benchmark
To water
Mercury
Transferred from caustic
0.1 µg/l
Parity with other sectors
To Air
Heavy metals
Combustion/incineration
See appropriate guidance
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Emission benchmarks Emissions
Techniques
Impact
Nitrogen oxides
3.7 Nitrogen oxides Other applicable standards and obligations (Extracts from standards are quoted for ease of reference. The relevant standards should be consulted for the definitive requirements.) Statutory Instrument 1989 No 317, Clean Air, The Air Quality Standards Regulations 1989 gives limit values in air for nitrogen dioxide. Statutory Instrument 1997 No 3043, Environmental Protection, The Air Quality Regulations 1997 gives air quality objectives to be achieved by 2005 for nitrogen dioxide. The UNECE Convention on Long-Range Transboundary Air Pollution Negotiations are now under way which could lead to a requirement further to reduce emissions of NOx. Waste Incineration Directive (Draft) requires a NOx level of 200 mg/m3. Benchmark emission values Table 3.7: Nitrogen oxides benchmark emission values
Media
Activity
Benchmark value Mass release
To air
From combustion plant
Basis for the benchmark Concentration See appropriate Guidance
Will require the use of good combustion chamber design and low NOx burners
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Emission benchmarks Emissions
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Nutrients (phosphates and nitrates)
3.8 Nutrients (phosphates and nitrates) Other applicable standards and obligations (Extracts from standards are quoted for ease of reference. The relevant standards should be consulted for the definitive requirements.) Table 3.8: Nutrients:water quality objectives in England, Wales and Northern Ireland
Water quality objectives
Nitrite
Ammonia total
England, Wales and Northern Ireland
(mg/l N)
(mg/l N, 90%ile)
Non-ionised Ammonia (total) (mg/l N, 95%ile)
Class 1
0.25
0.021
Class 2
0.6
0.021
Class 3
1.3
0.021
Class 4
2.5
-
Class 5
9.0
-
-
0.780
0.021
0.150
0.030
0.004
imperative:
-
0.780
0.021
guideline:
0.460
0.160
0.004
Designated freshwaters SI 1997/1331 Salmonid
imperative: guideline:
Cyprinid
Table 3.9: Nutrients:water quality objectives in Scotland
Water quality objectives
Nitrite
Ammonia total
Scotland
(mg/l N)
(mg/l N, 90%ile)
Non-ionised ammonia (total) (mg/l N, 95%ile)
Class Excellent
