Literature Review of Worms in Waste Management: Volume 1

Literature Review of Worms in Waste Management Volume 1 2007 Second Edition

Recycled Organics Unit PO Box 6267 The University of New South Wales Sydney Australia 1466 Internet: http://www.recycledorganics.com Contact: Angus Campbell Copyright © Recycled Organics Unit, 1999. Second Edition. First Published, 1999. This document is and shall remain the property of the Recycled Organics Unit. The information contained in this document is provided by ROU in good faith but users should be aware that ROU is not responsible or liable for its use or application. The content is for information only. It should not be considered as any advice, warranty, or recommendation to any individual person or situation.

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Table of Contents VOLUME 1 LITERATURE REVIEW..............................................................ERROR! BOOKMARK NOT DEFINED. TABLE OF CONTENTS ......................................................................................................................3 1. GLOSSARY OF TERMS ..................................................................................................................5 2. INTRODUCTION..........................................................................................................................7 2.1 PURPOSE ................................................................................................................................................7 2.2 OBJECTIVES ............................................................................................................................................7 2.3 DELIVERABLES ........................................................................................................................................7 2.4 METHODOLOGY ....................................................................................................................................7 2.5 SCOPE ....................................................................................................................................................7 3. VERMICULTURE INDUSTRY OVERVIEW.....................................................................................9 3.1 INTRODUCTION .....................................................................................................................................9 3.2 VERMILOGICAL RESEARCH ......................................................................................................................9 3.3 WASTE MANAGEMENT ...........................................................................................................................9 4. CURRENT STATUS OF VERMICULTURE IN AUSTRALIA .......................................................... 11 4.1 INTRODUCTION ...................................................................................................................................11 4.2 INDUSTRY SECTORS ..............................................................................................................................11 4.2.1 Primary Industry..........................................................................................................................11 4.2.2 Secondary Industry ......................................................................................................................11 4.2.3 Tertiary Industry ..........................................................................................................................12 4.3 EARTHWORMS IN WASTE MANAGEMENT ..............................................................................................12 5. VERMILOGICAL RESEARCH ...................................................................................................... 13 5.1 INTRODUCTION ...................................................................................................................................13 5.2 EARTHWORM CATEGORIES ...................................................................................................................13 5.3 COMMON COMPOST WORM SPECIES ...................................................................................................13 5.4 OTHER COMPOST WORM SPECIES ........................................................................................................14 5.5 COMPOST WORM KNOWLEDGE ...........................................................................................................14 5.6 VERMICOMPOSTING SYSTEMS ...............................................................................................................15 5.7 COMPOST WORM CONSUMPTION RATES.............................................................................................15 5.8 VERMICOMPOST/VERMICAST AS A MEDIUM ..........................................................................................15 5.8.1 Microbial Populations .................................................................................................................15 5.8.2 Structure ......................................................................................................................................15 5.8.3 Nutrient Value..............................................................................................................................16 5.8.4 Pathogens ....................................................................................................................................16 6. VERMICULTURE IN AGRICULTURE.......................................................................................... 17 6.1 INTRODUCTION ...................................................................................................................................17 6.2 WORM FARMING .................................................................................................................................17 6.3 VERMICULTURE PRODUCTS ..................................................................................................................17 6.3.1 Livestock and Cocoons ................................................................................................................17 6.3.2 Fishing (Live Bait) .......................................................................................................................18 6.3.3 Vermimeal....................................................................................................................................18 6.3.4 Vermicompost and Vermicast ......................................................................................................18 6.3.5 Vermiliquid ..................................................................................................................................19 6.4 FARMING WITH WORMS ......................................................................................................................19 7. VERMICULTURE IN ENVIRONMENTAL MANAGEMENT ......................................................... 20 7.1 INTRODUCTION ...................................................................................................................................20

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8. VERMICULTURE IN WASTE MANAGEMENT ............................................................................ 21 8.1 ORIGINS OF THE INDUSTRY ..................................................................................................................21 8.2 SCALE CLARIFIED ..................................................................................................................................21 8.3 VERMITECHNOLOGY.............................................................................................................................22 8.3.1 Windrow Systems .........................................................................................................................22 8.3.2 Continuous Flow Systems ............................................................................................................22 8.3.3 Tray or Stacking Systems .............................................................................................................23 8.3.4 Batching Systems .........................................................................................................................23 8.3.5 Wedge Systems.............................................................................................................................24 8.3.6 Vermiculture Ecotechnology Systems ..........................................................................................24 8.4 VARIABLES IN VERMICOMPOSTING........................................................................................................24 8.5 KEY VARIABLES IN VERMICOMPOSTING .................................................................................................25 8.5.1 Management/Maintenance...........................................................................................................25 8.5.2 Environmental Conditions ...........................................................................................................25 8.5.3 Feedstock Variables.....................................................................................................................28 8.5.4 Loading Rates ..............................................................................................................................32 8.5.5 Carrying Capacity (Stocking Capacity).......................................................................................33 8.5.6 Processing Capacity (Conversion rate) .......................................................................................35 8.6 OTHER VARIABLES IN VERMICOMPOSTING............................................................................................35 8.6.1 Square Metre Surface Feeding Area............................................................................................35 8.6.2 Bed Depth ....................................................................................................................................35 8.6.3 Inputs ...........................................................................................................................................36 8.6.4 Outputs.........................................................................................................................................36 8.6.5 Stabilisation .................................................................................................................................36 8.6.6 Transferability .............................................................................................................................37 8.7 ORGANIC MATTER TREATED USING VERMICULTURE .............................................................................37 8.8 VERMICULTURE ORGANICS PROCESSING RESEARCH .............................................................................38 8.9 AUSTRALIAN MID-SCALE VERMICOMPOSTING.......................................................................................40 8.9.1 Units Identified ............................................................................................................................40 8.9.2 Issues Impacting on Mid-scale Implementation...........................................................................41 9. RECOMMENDATIONS .............................................................................................................. 43 9.1 Vermicomposting Trials..................................................................................................................43 9.2 On-Site Technology Options ...........................................................................................................45 9.2 Particle Size Reduction Technology ...............................................................................................45 10. REFERENCES ............................................................................................................................ 46 VOLUME 2 11. APPENDICES................................................................................................................................. 11.1 DIRECTORY OF RELEVANT INTERNET SITES ................................................................................. 58 11.2 LIST OF RESEARCH INSTITUTIONS, MANUFACTURERS AND CONTACTS .......................................... 60 11.3 ANNOTATED BIBLIOGRAPHY ................................................................................................... 61 11.4 COPIES OF KEY LITERATURE ..................................................................................... ATTACHMENTS 11.5 PROMOTIONAL MATERIAL FOR MID SCALE VERMICULTURE SYSTEMS ............................ ATTACHMENTS

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1. Glossary of Terms Aerobic Conditions – composting and vermiculture systems require free oxygen to be available. Anaerobic Conditions – processing without oxygen. Capsule (Cocoon) – the oval shaped case containing worm eggs. Carrying Capacity – the total biomass in kilograms of worms that a specified surface area in m2 can contain under managed steady state environmental conditions. The maximum carrying capacity of biomass will vary widely depending upon: environmental conditions; individual worm species or mix of species; number, age and maturity of the population. Castings – the exretia of worms. Compost – material resulting from the controlled microbial transformation of organic materials under aerobic and thermophilic conditions. Compost Worm – selected species of earthworms appropriate for employment in organic waste management systems, and commonly cultivated commercially for such purposes. Feedstock – raw or pre-processed mixture of organic wastes in a form suitable for vermiculture application. Liquefied Castings – the liquid form of vermicast produced by steeping solid vermicast in aerated and circulated water, allowing to settle and sieving through fine gauze to remove suspended solids. Liquid Castings – liquids produced by the decomposition of organic materials combined with excess worm bed moisture , not fully worked through a worms digestive tract. Loading Rate – refers to the gross weight (kg) of a feedstock material that can be applied to a vermicomposting unit or system (equivalence in mm thickness per square metre surface feeding area) whilst maintaining aerobic conditions and moderate temperature range (15 – 30°C). Loading rate will be dependent upon: feedstock variables, compost worm spp. Employed, and to a lesser degree ambient temperatures. Manure – any organic product composed mainly of animal excreta. Mixing – blending of nitrogen rich compostable organic wastes with carbonaceous bulking agents and/or additives as required to produce feedstock into a form suitable for vermiculture application. Pre-processing – size reduction of compostable organic wastes (by chopping, macerating, grinding, blending or other like process) and mixing (see above) to produce feedstock suitable for vermiculture application. Pre-treatment – the primary digestion of raw or pre-processed organic wastes prior to vermiculture application. Processing Capacity –the maximum gross weight of a feedstock (kg) per unit area (square metres) that can be applied per unit time under managed environmental conditions.

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Processing capacity will vary with: environmental conditions; loading rate (including feedstock variables); and, carrying capacity (including compost worm spp. employed). Soil Conditioner – any composted or non-composted material of organic origin, that is produced or distributed for adding to soils. This term also includes "soil amendment", "soil additive", "soil improver" and similar terms, but excludes polymers which do not biodegrade such as plastics, rubber, and coatings. Vermicast – the excreta of worms in its pure form, produced by the action of microbiological life within the digestive tract of the worm. Vermicompost – mixture of vermicast and unprocessed organic matter, it may also contain worm capsules and small worms.

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2. Introduction 2.1 Purpose The Southern Sydney Waste Board has identified mid-scale vermicomposting as one available technology option for on-site organic waste stabilisation that may contribute to the waste management needs of a range of commercial and industrial (C&I) sector enterprises. The purpose of this study is to contextualise the depth of knowledge and application of mid-scale vermicomposting technology and systems for the on-site treatment of organic waste, and the potential use of products from this waste management technique.

2.2 Objectives This report is a literature review of vermiculture with two key objectives: 1. 2.

To establish the current status of mid-scale vermiculture; and, To investigate the range of relevant organic matter that could be managed through vermiculture systems. Particular attention has been given to reviewing the use of worms in waste treatment and identifying the: types of material consumed; consumption rates; quality of vermicast; and, specific mid-scale vermicomposting units in Australia for on-site C&I sector food waste treatment.

2.3 Deliverables The deliverables from this study include: 1. 2. 3. 4. 5. 6.

Literature review; Directory of relevant internet sites (Appendix 1); List of major research institutions with organisational contacts, and Australian manufacturers with organisational contacts (Appendix 2); Annotated bibliography (Appendix 3); Copies of key literature as permissible under IPR constraints (Appendix 4); Copies of promotional material and product specifications for commercially available mid-scale units. Units capable of processing 20 kg - 250 kg/wk (Appendix 5).

2.4 Methodology Methods used in this study involved: the investigation of available Australian and international vermiculture literature and internet resources for review; site visits to view mid-scale vermiculture installations; and, direct communication with current developers and manufacturers of on-site mid-scale vermiculture units in Australia. Direct communication with innovators in this dynamic industry was necessary to develop an understanding of their experience in installation, on-site management and development of vermiculture technologies appropriate to the on-site management needs of the C&I sector enterprises.

2.5 Scope Vermiculture is an emerging technology and the mid-scale sector of the vermiculture industry has largely been neglected until recently. This is a young and dynamic industry, characterised by a number of very new products, most technologies are immature and are Recycled Organics Unit

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still under development. The market is characterised by rapid entry and exit of technologies. This report will give an overview of the vermiculture industry and identify the key areas of activity in vermiculture including: vermilogical research; vermiculture in agriculture; vermiculture in environmental management; and, vermiculture in waste management. Emphasis will only be given to those parts of the industry that relate directly to the use of composting worms in waste management. A range of other areas outside of this main focus are sign posted only. Specific attention is given to identifying and discussing: •

Vermitechnology;

•

Variables in vermicomposting;

•

Organic matter treated with an emphasis on C&I waste streams; and,

•

Australian mid-scale vermicomposting.

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3. Vermiculture Industry Overview 3.1 Introduction In this report reference is given to the body of literature available to investigate various components of the vermiculture industry. The vermiculture industry consists of several interconnected key areas of activity, including: Vermilogical Research – scientific investigation of all things relating to earthworms; Vermiculture in Waste Management – the use of earthworms and earthworm technology in waste management practices; Vermiculture in Agriculture – the use of earthworms and related products in agricultural practices such as worm farming and farming with worms; and, Vermiculture in Environmental Management – the use of earthworms and related products for environmental management and assessment. Earthworms in agriculture and environmental management are largely outside the scope of this report and will only be outlined in brief. These vermiculture activities, as opposed to waste management vermiculture activities, generally involve: the use of different earthworm species and associated biota; a range of different ecosystem requirements; and, different management practices and objectives. There is, however, some overlap with the activities of vermiculture in waste management and some relevance to the C&I sector. These convergences will be identified below.

3.2 Vermilogical Research The term vermilogical research is a broad 'brush-stroke' term used here to describe scientific investigation of the biology and ecology of earthworms. Much of this research informs the application of the other three core areas of activity in vermiculture.

3.3 Waste Management The use of earthworms in waste management by utilising and breaking down organic wastes has received increasing attention over the last 20 years, where research programs and commercial projects have been developed in many countries on all continents. There have been several catalysts for this including: The growing recognition in developed countries that organic matter in the waste stream can be used as a resource rather than going to landfills where it creates a range of environmental problems that are costly to ameliorate; The diversion, remediation and recycling of organic matter from the waste stream can be achieved by a range of alternative treatment methods that create a marketable product for sale instead of disposal to landfill sites. Waste disposal fees are becoming extremely costly, especially in Europe and North America, where many innovations in vermicomposting are occurring; Increasing recognition of vermiculture, as a viable alternative to composting, by utilising the vermicomposting process which dramatically increases the turn around time between treatment and end-use;

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A rapid increase of detailed scientific research into the treatment of a broad range of organic residuals by earthworms and the subsequent development and implementation of vermitechnology for domestic, commercial and industrial purposes; and, An increase in the application of worm farming, domestic vermicomposting and largerscale pilot project vermicomposting systems that, if managed correctly, are odourless, efficient, and produce a high quality range of value added products. Vermicomposting is the method used in the vermiculture industry for waste management. Vermicomposting is engaged to achieve one, or more, of the following three outcomes: •

To produce earthworm biomass for the purposes of worm farming;

•

To produce vermicast for the purposes of agriculture and environmental management;

•

To reduce organic waste volumes through vermistabilisation.

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4. Current Status of Vermiculture in Australia 4.1 Introduction The vermiculture industry in Australia is still in its infancy (Abbott and Atkins, 1997; Cheal and Lewis, 1997). It is still an emergent technology where most activity has been targeted at developing the domestic market with the promotion of small-scale vermicomposting units for point-source remediation (Christenson and McLachlan, 1994; Reln, 1996). More recently, the large-scale commercial and industrial vermicomposting market has gained a foothold in treating, for example: municipal biosolids mixed with yard trimmings in Hobart, Tasmania (Williams, 1994; Applehof et al, 1996); biosolids and vegetable residuals in Newcastle, New South Wales (Applehof et al, 1996); mixes of sewage sludge, factory waste and animal manure in Redlands, Queensland (Lotzof, 1998); biosolid and green waste mixes in Bathurst, New South Wales (Scarborough, 1999). Commercially viable vermicomposting technologies have been investigated since 1993 with in excess of 300 tonnes per week being processed (Williams, no date). The mid-scale market has been largely neglected until very recently with most activity being engaged in schools as a part of waste education (Buckerfield and Wiseman, 1996; Natoli, 1996; Campbell, 1998; Carroll, 1999), or, through trials of mid-scale systems for businesses (Scott, 1998; Greenscene, no date). There is a paucity of material and available data on mid-scale (see section 7.1) vermiculture in Australia for review, especially, with respect to the objectives of this report. The use of earthworms in waste management cuts through the boundaries between primary, secondary, and tertiary industries. In Australia, as is evident overseas, there are several core sectors within these industries associated with earthworms in waste management.

4.2 Industry Sectors 4.2.1 Primary Industry Worm farming – the production of worms for livestock, vermimeal (protein supplement), live bait (fishing), and medicinal uses. Vermicomposting – focuses on using worms for the production of vermicasting products as soil amendments and potting mixes. Vermistabilisation – focuses on using worms by utilising vermicomposting techniques to stabilise and reduce the volume of specific waste streams. Farming with worms – using worms in agriculture for on-site waste management, productivity improvements of crops and pastures, and in horticulture to enhance plant growth and propagation.

4.2.2 Secondary Industry Manufacturing – the production of vermitechnology equipment and related products such as vermicomposting systems and harvesting equipment. Processing – the processing of vermiproducts such as vermicast blends and packaging, protein feed supplements (vermimeal processing).

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4.2.3 Tertiary Industry Vermilogical Research – scientific investigation of all things related to vermiculture. Waste Services – the supply of consulting and contracting services to conduct waste audits and to advise, and set up, vermicomposting/worm farming/etc facilities and businesses. Marketing and Retail – the promotion, distribution and sale of vermiculture related products.

4.3 Earthworms in Waste Management The use of earthworms in waste management is largely a straight forward process (ie. waste in – worms do the vermicomposting – products out). It remains the same for all of these sectors, the objective, or desired outcome, will determine the focus of activity and the route taken to achieve the end result. Hence, the focus will determine the various decisions made for the technology used, the scale of operation, the processes/systems/strategies engaged, and the quality of the products. The expansion of the vermiculture industry in Australia has been hampered in two ways: 1.

the recent failure of worm farming buy-back schemes;

2.

differing processing methods, levels of quality/process control and varying feedstocks result in, different quality and performance of vermicompost products on the market. With respect to this second point, there is however, a burgeoning knowledge base on the effects of vermicompost product applications for increasing productivity in crops and pastures, earthworms as bioaccumulators and pathogen consumers. The Australian Worm Growers Association (AWGA) are currently circulating draft "Best Practice Guidelines" and are engaged in industry consultation attempting to address these issues (refer to Appendix 2 - Internet directory).

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5. Vermilogical Research 5.1 Introduction Vermilogical research involves an understanding of earthworm morphology, taxonomy, biology, physiology, biogeography, and ecology. Progress in all aspects of this research has periodically been summarised in key texts such as: Edwards and Lofty (1972); Edwards and Lofty (1977); Satchell and Martin (1985); and, Edwards and Bohlen (1996). Six International Symposium's on Earthworm Ecology (ISEE) have been held since 1981, the latest was ISEE 6 in 1998. The ISEE's represent a core forum for presentation of earthworm research and has resulted in several edited publications including: Satchell (1983); Bonvicini-Pagliai and Omodeo (1987); Kretzschmar (1992); and, Edwards (1997). Key texts that focus specifically on earthworm ecology include: Lee (1985); and, Edwards (1998a). Not all vermilogical research is relevant to the application of vermiculture in waste management. The relevance largely depends on the type of systems being applied and the species that are most appropriate for the job.

5.2 Earthworm Categories Earthworms may be grouped into three categories: epigeic; anecic; and, endogeic (Edwards and Bohlen, 1996). These groupings generally reflect morpho-ecological distinctions between species adapted to different habitats. These categories are character extremes, and many worm species evidence behaviours from more than one category. Others will sit squarely within the category definition. The epigeic group are generally surface dwelling species that inhabit and feed on decomposing litter on the soil surface, rarely ingesting soil. They have rapid mobility, are relatively short-lived, small to medium in size, grow and reproduce quickly. The earthworm species that have evolved with these characteristics are predominantly used in vermicomposting. The anecic group are burrowing earthworms that construct large, permanent, vertical burrows and feed on decomposing litter at the soil surface or pull it into their burrows. They have a rapid withdrawal response, are large in size, relatively long-lived and have a longer growth and reproduction time than epigeic species. Anecic species may be used in vermicomposting but usually in combination with epigeic species. The endogeic group of earthworms live in extensive horizontal burrows and feed on mineral soil and rich organic matter. These species are never used in vermicomposting.

5.3 Common Compost Worm Species In Australia, the CSIRO has conducted surveys of the earthworm species predominantly found in Australian regions (Baker and Kilpin, 1992; Baker and Barrett, 1994) and identified the range of species most commonly found in compost piles and vermicomposting facilities. They are mostly of European origin, introduced accidentally at the end of the nineteenth century, probably in potted plants. The species commonly found in composts and vermicomposts include: Eisenia andrei (red tiger worm, commonly sold as red or red wriggler); Eisenia fetida (tiger worm);

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Eudrilus eugeniae (African nightcrawler); Lumbricus rubellus (red worm); Perionyx excavatus (Indian blue worm); Fletcherodrilus spp. (native to Australia); Heteroporodrilus spp. (native). The E. eugeniae and P. excavatus are of tropical origin and are best suited to indoor or temperature controlled environments, but P. excavatus has been cultivated successfully as far south as central Victoria (Murphy, 1993). Eisenia spp. are the dominant commercial compost worm for temperate areas, including the Sydney bioregion. There are several reasons why they are preferred for composting, these include: 1. 2. 3. 4.

Their rapid consumption of food, rate of breeding and rate of natural increase; Capacity to inhabit, consume and breed in a high nutrient environment; Suited to a broad range of climates and environmental conditions; and, They are disinclined wander if acceptable environmental conditions and feed are available. This paper focuses on Eisenia spp. and P. excavatus as the compost worm species commercially cultivated and available. These species are appropriate compost worms for temperate areas, including the Greater Sydney Region.

5.4 Other Compost Worm Species Baker and Kilpin (1992) also rate compost as a suitable habitat for several other species, but these were only occasionally found in compost during their survey: •

Amynthus corticis;

•

Eiseniella tetraedra;

•

Microscolex dubius;

•

Polypheretima elongata;

•

Diplotrema spp. (native);

• Spenceriella spp. (native). Such worms are not recommended, preferred, or cultivated commercially by the vermiculture industry in Australia, although, they may be present in mixed vermicomposting systems and contribute to the digestion process of organic wastes.

5.5 Compost Worm Knowledge All earthworm species have a specific range of environmental conditions and ecological requirements that must be met for them to thrive. The most successful vermicomposting species are those with a fairly broad range of tolerances. The optimum environmental conditions required by the most common species used in vermicomposting facilities is relatively well known. Although, Edwards (in Slocum, 1998: 19) claims that:

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“Much of the basic research into temperature, pH, ammonia, salt and moisture tolerances, feedstock potential's and growth and reproductive rates of worms with the potential for use as waste managers has not yet been done.”

5.6 Vermicomposting Systems The challenge to design systems that accommodate these needs for maximum efficiency in processing organic wastes is still an emergent vermiculture technology. What is known for specific species and waste streams will be highlighted below.

5.7 Compost Worm Consumption Rates Earthworms can ingest more than their own body weight in organic matter each day and some vermicomposting species can process vast quantities very rapidly given optimum conditions. This rate of ingestion is more commonly observed to be between 50-100% of worm biomass. However, the rate of ingestion is largely dependent upon the species of earthworm, the maturity of individuals, the rate of reproduction, the population densities and several feedstock variables, given optimum environmental conditions.

5.8 Vermicompost/Vermicast as a Medium 5.8.1 Microbial Populations Earthworms play a major role in the breakdown of organic matter and in the cycling of nutrients in natural ecosystems. They are a part of a complex chain of chemical, biochemical, biological, and ecological interactions. Earthworm mouthparts are not capable of chewing or biting, so they rely on the decomposition of organic matter by microorganisms such as, bacteria, algae, fungi, nematodes, protozoa, rotifers and actinomycetes, before they can ingest the softened material along with the microorganisms. Earthworms possess a grinding gizzard that fragments the organic residuals. They ingest microorganisms and depend on them as their major source of nutrients (Edwards and Bohlen, 1996), but also, the earthworm gut secretes mucus and enzymes that selectively stimulates beneficial microbial species (Doube and Brown, 1998). Earthworms promote further microbial activity in the residuals so that the faecal material, or casts that they produce, is much more fragmented and microbially active than what the earthworms consumed (Edwards, 1995). Effectively, earthworms inoculate the soil, or organic matter, with finely ground organic residuals and beneficial microorganisms which increases the rate of decomposition and enables further ingestion of microorganisms by earthworms.

5.8.2 Structure Castings are pH neutral and well aggregated in structure, they retain moisture and enhance aerobicity. In effect, earthworms create their own ideal environment for enhancing earthworm and beneficial microbial activity. Castings also provide the ideal habitat for cocoon (egg capsule) survival in otherwise toxic environments (Mba, 1989). The good structure of castings is due to the action of worms in digestion and aggregation of organic material into crumbs. The material is also susceptible to compaction in a vermicomposting unit where composting worm species usually inhabit only the top 100 - 200 mm. It has been suggested that in depths of over 450 mm, compaction will result in an absence of oxygen and hence, no worm activity. Three issues arise out of the compaction question: 1. Technological design issues – for example, the design depth of a vermicomposting chamber or, do continuous flow reactors allow sufficient aeration through the system; Recycled Organics Unit

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2. Management issues – rarely are vermicomposting units aerated manually; and, 3. Species selection issues – for example, are polycultures of burrowing and composting worm species a solution where burrowing earthworms will aerate the soil at depth.

5.8.3 Nutrient Value Edwards (1995) claims that, through the vermicomposting process the important plant nutrients in the organic material — particularly nitrogen, phosphorus, potassium and calcium — are released and converted through microbial action into forms that are more soluble and available to plants than those in the parent compounds. Many comparative studies between vermicomposting and composting systems have shown that earthworms (especially in trials conducted using composting worms) will accelerate the mineralisation of organic matter, accelerate the breakdown of polysaccharides, increase humification, lower the C:N ratio, lower the bioavailability of heavy metals (Elvira et al, 1996a, 1998; Dominguez, 1997; Edwards and Bohlen, 1996). It should be noted however, that the nutritional quality of the vermicompost is largely dependent on the nutritional quality of the feedstocks. Earthworms will transform, or convert, organic nutrients into more available inorganic forms, but they cannot create nutrients when they are not present to begin with. Research has tended to focus on the benefits to plants and soil structure through the activity of earthworms (Edwards and Shipitalo, 1998; Kretschmar, 1998; Doube & Brown, 1998; Baker, 1998). Plant growth trials comparing vermicomposts consistently outperform composts and commercial plant growth media (Edwards and Burrows, 1988; Edwards, 1998b; Subler et al, 1998). Vermicomposts have a better structure than other media and it is suggested that vermicomposts contain plant growth hormones, soil enzymes, high microbial populations, and that earthworms selectively cull pathogens and harmful microorganisms in the soil (Benitez et al, 1999; Edwards and Bohlen, 1996).

5.8.4 Pathogens There is increasing evidence that human pathogen species of microorganisms, are selectively culled by earthworms (Dominguez, 1997; Doube and Brown, 1998; Scarborough, 1999), and pathogens such as Escherichia coli and Salmonella sp. do not survive vermicomposting (Edwards and Bohlen, 1996). Dominguez (1997), conducting trials with small-scale continuous flow reactors using biosolid feedstocks, found that faecal coliform bacteria dropped from 39,000 MPN/g to 0 MPN/g after 60 days vermicomposting.

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6. Vermiculture in Agriculture 6.1 Introduction For vermiculture in agriculture, overlapping interest occurs at either end of the waste management stream. At one end, is the need to deal with specific agricultural by-products, or wastes, and vermicomposting is identified as one sustainable method of utilising these wastes and turning them into a resource. This has been engaged on a large commercial scale mainly using windrows for the treatment of pig solids (Edwards et al, 1985; Chan and Griffiths, 1988; Wong and Griffiths, 1991) and cattle solids (Hand et al, 1988; Edwards, 1998b). At the other end is the use of the resultant vermicompost products, such as: the application of vermicompost as soil amendments in agroecosystems; the use of vermicast in potting mix blends for plant propagation; and, vermicompost, or vermicast, as a plant growth stimulant. There is a very large body of literature on most aspects of farming with worms and worm farming. These resources will be identified in Appendix 1 – Annotated Bibliography.

6.2 Worm Farming A number of introductory and more detailed texts cover the broad issues of worm farming. Some of these texts target the domestic scale for home based waste reduction and gardening including: Applehof (1997); Brown (1994); Grossman and Weitzel (1997); and, Windust (1994). A number of texts that target worm farming in Australia include: Murphy (1993); Lambert (1994); Petit (1996); and, Windust (1997). Worm farming is a primary industry (stock husbandry for the purpose of natural population increase) and therefore, as a microlivestock production process, it fits relatively easily into the broad descriptive activity of vermiculture in agriculture. Due to the very nature of the production process for worm farming, the utilisation of organic waste products for inputs determines an engagement with vermiculture in waste management regardless of the focus on the end product. However, the end product focus determines the method of operation and production process choices made by the worm farmer. Rarely does a worm farmer focus on only one of the five core products identified below. Profitable synergies tend to be exploited wherever opportunities are identified. In all cases, management, education, and marketing, are crucial factors for business success. The production of vermicompost or vermicastings for sale, although not the primary focus, is almost always considered as a secondary, and even the primary, income stream.

6.3 Vermiculture Products 6.3.1 Livestock and Cocoons For livestock production the focus is not necessarily on earthworm biomass increase (kg) but population increase (number). Although, most farmers in Australia sell worms by the kilogram and biomass is the easiest method to quantify, an approximate measure of 4000 worms per kilogram is often used to estimate worm populations. Critical factors include: Production processes for harvesting and separation of worms and cocoons from castings; Production processes for maximising the breeding cycle such as regular feeding; and,

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Species are selected for faster growth, maturity and fecundity, including epigeic species such as Eisenia fetida, Eisenia andrei, Lumbricus rubellus and Perionyx excavatus.

6.3.2 Fishing (Live Bait) For the production of live bait the focus is on biomass. Large, fat worms are considered the best quality product and these command a high price from fishermen. Critical factors for the production of live bait include: The use of specific feedstocks for fattening worms such as including corrugated cardboard bonded with edible glue (Murphy, 1993), raising worms on dog faeces (Moran, 1999), or paper sludge (Fayolle et al, 1997); Managing the population by removing cocoons to reduce competition (Murphy, 1993); Species selection such as Perionyx excavatus – the Blue worm (Murphy, 1993), Eudrilus eugeniae – the African nightcrawler (Windust, 1997), Lumbricus terrestris – the Canadian nightcrawler (Windust, 1997), or Dendrobaena veneta (Fayolle et al, 1997); The 'nightcrawlers', as the name suggests, have a tendency to wander, so attention to stock containment considerations in vermiculture facility/technology design and management is crucial. Eisenia fetida, the most common composting worm used in worm farming, is unsatisfactory for use as live bait because, when threatened, it will exude a fetid, unpleasant-smelling yellow coelomic liquid (Murphy, 1993; Edwards and Bohlen, 1996). Also, several trials using E. fetida as a vermimeal feedstock for rainbow trout and eels found this species to be unpalatable and will not support fish growth (Stafford and Tacon, 1988).

6.3.3 Vermimeal For the production of livestock for vermimeal the focus is on producing worms that are not contaminated and contain sufficient quantities of specific proteins and essential amino acids. The quality of feedstocks plays a key role. Also, the presence and quantity of different proteins varies between different species (Stafford and Tacon, 1988). Only a limited amount of research has been engaged on the production of earthworms as a highprotein feed supplement (Williams, no date). Sabine (1988) gives an overview of earthworms as animal feed and highlights the research needs of this process. Edwards and Neiderer (1988) give a detailed analysis of the production and processing requirements necessary for vermimeal and Edwards (1998b) gives an overview of the production of worm protein and technologies. The potential of this market has not yet moved from research to commercial production in Australia.

6.3.4 Vermicompost and Vermicast When vermicast, or vermicompost, production becomes the primary focus, more attention must be paid to the quality and mix of feedstock inputs. This is a very different motivation to waste management systems, particularly on-site vermistabilisation systems, which aim to manage any and all food organics produced as a substitute to sending such materials to landfill. Vermicast production is a very different process as a result, and requires significant variance in management. Such vermicomposting systems aim to maximise throughput, and the quality of castings as outputs. Vermicast is the excretia of worms in their purest form, whereas, vermicompost is a mixture of vermicast and unprocessed organic matter. There are a range of commercial Recycled Organics Unit

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products on the market that vary in quality and mix. Some vermicomposts are produced as soil amendments and others are produced as potting mix blends. There is a fairly large body of literature that has investigated comparative studies of vermicompost with potting mix mediums and composts, nutritional quality of vermicastings and vermicomposts, the application of vermicast and vermicompost as plant growth mediums and soil amendments. However, the vast majority of these studies have used agricultural wastes (eg. manures), large-scale industrial wastes (eg. papermill sludge) and municipal wastes (eg. sewage sludge) as their main feedstocks and substrates in vermicomposting operations. This literature is identified in Appendix 1 – Annotated Bibliography.

6.3.5 Vermiliquid Vermiliquid is essentially a by-product of the vermicomposting process. There are two forms of vermiliquid. Liquid castings are the liquids produced by the decomposition of organic materials and the excess bed moisture that has percolated through vermicompost. Liquefied castings is the liquid form of vermicast which is produced by steeping vermicast in aerated and circulated water and then sieved to remove the solids. Some worm farmers produce and market vermiliquid as a high nutrient liquid fertiliser. Determining the quality of vermiliquid is an inexact science, using the colour as the quality determinate. One method used to increase the production of liquid castings is to regularly 'soak' (never more than 100% moisture) the vermicompost unit and catching the liquid castings after it has percolated through the vermicompost bedding. The evidence for the nutritional value of vermiliquid products is largely anecdotal. There is a paucity of literature available that has investigated the use and quality of vermiliquids.

6.4 Farming with Worms The use of vermiculture in agroecosystems is largely outside the scope of this report. It is signposted here as farming with worms, in recognition that worm farming and farming with worms are largely different approaches to the use of earthworms for productivity improvements (Buckerfield, 1994). These vermiculture activities, as opposed to waste management vermiculture activities, generally involve: the use of different earthworm species and associated biota; a range of different ecosystem requirements; and, different management practices and objectives. There is, however, some overlap with the activities of vermiculture in waste management. These convergences are identified in the use of vermicomposting systems to utilise and convert agricultural waste streams such as, manures and vineyard, or orchard, green waste clippings. Also, in the use of vermicast blends as potting mix media and fertiliser, vermicompost as a soil amendment, inoculation of earthworms (some burrowing species raised intensively) for productivity improvements in crops and pastures, and the use of vermicast for plant propagation and as plant growth stimulants in the horticulture industry. Some key references include: the proceedings of a symposium on the ecology and biogeography of earthworms in North America (Hendrix, 1995); Curry (1998) gives a literature review of factors that affect earthworm abundance in soils; Hendrix (1998) summarises current research on earthworms in agroecosystems; and, Baker (1998) makes reference to southern Australia in an overview of the ecology, management, and benefits of earthworms in agricultural soils. Recycled Organics Unit

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7. Vermiculture in Environmental Management 7.1 Introduction There is an overlapping of activities between vermiculture in environmental management and vermiculture in waste management. This is mainly in the vermicompost production process of waste steam selection and utilisation where, knowledge of earthworm tolerance to the toxicity of specific waste streams is applied in the design process for system management. Earthworms reduce the bioavailability of heavy metals. Dominguez (1997) reported that even though carbon losses, through mineralisation, increased the total amount of heavy metals in a vermicomposting system, the amounts of bioavailable heavy metals is decreased significantly. Ecotoxicology also plays a role in research engaged to determine how, and to what degree, earthworms act as bioaccumulators of pesticides and heavy metals (Eijsackers, 1998; Edwards and Bohlen, 1996). There is also overlap with the use of vermicompost in environmental remediation of contaminated sites, or denuded land, in conjunction with earthworm inoculation. To a lesser extent, earthworms are used in landscaping. Much of the ecotoxicology research was highlighted at a conference on the ecotoxicology of earthworms held at Sheffield University, UK in 1991 (Greig-Smith et al, 1992). A precursor to this are the sections on earthworms as indicators of environmental contamination, and their role in land reclamation, soil amelioration and land improvements (Edwards and Neuhauser, 1988). More recently Eijsackers (1998) has reviewed the literature on earthworms in environmental research and Reinecke and Reinecke (1998) evaluate new approaches in the use of earthworms in ecotoxicological evaluation and risk assessment.

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8. Vermiculture in Waste Management 8.1 Origins of the Industry Vermilogical research into waste management was initiated in the late 1970's with a conference held in Syracuse, New York, USA (Hartenstein, 1978), highlighting research into the conversion of biosolids through vermicomposting being engaged by researchers at Cornell and Syracuse Universities. This was followed by a workshop in Kalamazoo, Michigan, USA, on the stabilisation of organic residues (Applehof, 1981). The waste management focus was further enhanced by a symposium on earthworms in waste and environmental management held in Cambridge, UK, and the subsequently influential publication of the proceedings (Edwards and Neuhauser, 1988). Edwards (forthcoming) is soon to publish an edited "Manual of Vermicomposting" which will be a summary of the state of knowledge in vermicomposting ranging from various technologies in use to studies on vermicompost quality.

8.2 Scale Clarified This paper adopts three scales of vermiculture technology for on-site application: the small-scale (domestic); the mid-scale (either domestic or commercial); and, the largescale (commercial). The categories are fairly arbitrary, and the boundaries between these scales are not rigidly fixed. Defining the scale also depends on the criteria being used to determine the scale. Two distinct criteria will result in different scale interpretations. These scale criteria may be defined as: Quantity Scale — based on quantity (by weight/week) of organic matter being treated; and, 2

Unit Scale — based on size (m of feeding surface area) of the units used to treat organic 1 matter . The following table is a suggestion for defining the boundaries between the various scales according to the criteria. These definitions have been used to determine applicability of vermiculture units and vermiculture operations when compiling this report on mid-scale vermiculture.

Table 1: Definitions of scale for vermicomposting operations and units Criteria

Scale Small-Scale

Mid-Scale

Large-Scale

Quantity Scale

< 20 kg/wk

20 - 250 kg/wk

> 250 kg/wk

Unit Scale

< 0.5 m

2

0.5 - 3.5 m

2

> 3.5 m

2

It was necessary to take both criteria into account when assessing whether mid-scale is in use. The quantity scale can, however, be misleading on two counts, if used on its own: The processing rate for different organic matter will vary according to: a) the waste stream; b) the species of worms; and, c) the management practices.

1

Note that a 'Unit' is not the same as a 'System'.

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Units are often modular in design. A vermiculture operation may employ the use of a number of mid-scale units to process a large-scale quantity of organic matter. Small-scale vermiculture units have been manufactured and strategically marketed to the domestic (or household) consumer for several years now. More recently, large-scale vermiculture units have been developed in conjunction with a push into industrial based vermiculture applications. In some cases mid-scale units have also been developed and used in these large-scale operations. The development of mid-scale vermiculture units to treat mid-scale commercial and industrial waste streams on-site is the most recent focus for vermiculture projects. Hence, mid-scale vermiculture is an emerging technology. It is a dynamic niche market highlighted by rapid entry and exit of a number of very new products. It shows promise, but there is as yet very little available data on how effective these systems are and the processing rates for different waste streams that these systems are capable of. Most available data is in the form of gross mass figures supplied by the manufacturers of the units.

8.3 Vermitechnology There is a broad range of vermitechnology that has been developed, adapted, and manufactured for use in the vermiculture industry. This ranges from equipment and instruments, processes and strategies in management and marketing, and methods and systems. For this report, the range of vermicomposting systems are described here, because they are directly relevant to mid-scale vermicomposting and will impact on the choices made for on-site C&I waste management.

8.3.1 Windrow Systems Windrows are the traditional, low-tech method for large-scale vermicomposting (Jensen, 1998). For the windrow method, organic materials are placed on the ground up to 50 cm in depth in long rows and worms are introduced to the material. Windrow systems on the soil surface are relatively inefficient (Edwards, 1998b) and generally result in an inferior vermicompost product because nutrients are lost through volatilisation and leaching (Edwards, 1999). In Australia, windrow systems are still the predominant method of vermicomposting (Edwards and Steele, 1997). Other drawbacks of windrow systems include: the requirement of large areas of land; they are labour intensive for feeding and harvesting (biomass and castings); they process organics relatively slowly, taking six to eighteen months to produce a stable vermicast (Edwards, 1995); and, they are usually exposed to a broad range of environmental conditions. Windrows are not appropriate for on-site C&I waste treatment.

8.3.2 Continuous Flow Systems Continuous flow vermicomposting system technology was first developed and tested in 1981 at the Rothamstead Experimental Research Station, Silsoe, UK (Edwards, 1995). A continuous flow reactor is at the high-tech end of vermicomposting systems, but there are low-tech designs as well. It can be designed for manual or automated operation for feeding and collection. Examples of automation include travelling gantries (Edwards, 1995; Subler, 1999) and trickling filters (Hand, 1988). The basic aspects of design are: the vermicomposting container is raised on legs above the ground; the bottom is a mesh floor and a breaker bar loosens the bottom layer of castings Recycled Organics Unit

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so they can fall through for collection; and, it enables top feeding of feedstocks. Edwards (1995) claims that a continuous flow reactor, managed effectively, can fully process 900 mm deep layers of suitable organics in less than 30 days (ie. approximately 30 mm per day loading rate). Continuous flow reactors are presently being manufactured for the small-scale to the largescale. They are the most common mid-scale vermicomposting systems in use. Commercial, or manufactured, examples of this system include: the 'eliminator'; the 'worm wigwam'; the 'VC 2000'; and, tumbleweed's mid-scale unit. DIY examples that use continuous flow principles include: the 'OSCR reactor' which has been utilised extensively and adapted by some in the USA (Holcombe and Longfellow, 1995; Cornish, 1998); and, the 'raised worm ranch' which has been advocated and implemented in Australian schools (Campbell, 1998; Carroll, 1999).

8.3.3 Tray or Stacking Systems Tray, or stacking, vermicomposting systems are another popular method. These systems, along with the batching systems, are the most common technologies used for small-scale (domestic) applications (Applehof, 1988), although they are also used in some mid-scale operations (Scott, 1998). A tray system involves stacking several trays (usually up to three 150 mm in depth) on top of one another. Feedstocks are applied to the bottom most tray and when the tray is full of vermicompost the next tray is added and feedstocks are applied to the next upper most tray to encourage the worms to move out of the bottom tray and consume the fresh feed. When the next tray is full of vermicompost a third tray is added and the first tray should be relatively free of worms enabling the harvesting of castings. This tray is then empty and ready to be placed on top again. Edwards (1988) assessed the performance and design components of tray systems and concluded that these systems can be relatively labour intensive, requiring lifting of the upper trays to access the lower trays and the larger the vermicomposting unit becomes the more difficult this operation for castings removal is. Automated rotating tray systems may be an answer but this would involve higher, initial, capital expenditure. The Worm Network vermicomposting tray design utilises sliding draw trays, 200 mm in depth, which circumvents the need for lifting, but due to the mid-scale size of this unit, full trays are still very cumbersome, requiring design modifications such as ball bearings (Scott, 1999). A climatic advantage of the tray system is that in a warm temperate environment where cold temperature extremes do not present a problem, the extra surface area to volume ratio ameliorates against a system over heating, however, moisture loss is higher if it is not an enclosed system. Another advantage of a tray system, especially with respect to the limited space available for a commercial premises to implement a vermicomposting system, is that several trays may be used for feedstock application at one time. Therefore, reducing the vermicomposting units footprint and achieving greater efficiencies in a smaller space.

8.3.4 Batching Systems Batching systems, or box systems, are a relatively popular and simple design for small-scale vermicomposting units (Applehof, 1988; Slocum and Frankel, 1998; Slocum, 1999a). Batching systems have been experimented with on all scales, but many of the

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disadvantages (without the advantages) associated with the tray systems are also applicable for the batching system (Edwards, 1988). An Australian mid-scale example of a batching system is the 'Worrigee' DIY unit used by the Shoalhaven District Memorial Hospital in Nowra, New South Wales (Lawler, 1999). This unit exemplified the labour intensive requirements for the extraction of castings and separation of worms observed by Edwards (1988). Due to the labour intensive methods required to harvest a by product from a batching system, these system, for mid-scale applications, are usually by passed, in the C&I sector, in favour of tray and continuous flow systems. Batching systems are often applied in situations where there is very little start-up capital and by not-for-profit organisations such as, schools (Applehof et al, 1993; Payne, 1999) and hospitals (Lawler, 1999).

8.3.5 Wedge Systems These systems are largely unexplored in the literature and Edwards (1999) identified the need for trials with this system to investigate it's potential. In a wedge system, the horizontal feeding method is used, where feed is applied to an 'open face' of the bedding, usually at a 45˚ angle, in an even layer (Mitchell, 1997). Edwards has suggested the use of a wall to start a system off and then move outwards, harvesting castings from behind (1999). However, Mitchell (1997) found the horizontal method of feeding to be less successful than the vertical or furrow methods used in other systems. Even though a spare wall may be allocated to use this method for on-site vermicomposting, the waste treatment process is not contained and would utilise too much space.

8.3.6 Vermiculture Ecotechnology Systems The vermiculture ecotechnology system has been developed over many years of experimentation and application by Bhawalker (1999), of the Bhawalker Earthworm Research Institute in Pune, India. It is used extensively in India (White, 1995), with some recent trial applications in the U.S.A (Werner, 1997; Boggess and Frankel, 1997; Frankel and Boggess, 1997, 1998). Vermiculture ecotechnology is applicable from small-scale (invessel) to very large-scale (in-ground) vermicomposting. The vermiculture ecotechnology system is an holistic ecosystem approach to organic waste treatment, utilising burrowing earthworms, microorganisms and the root zone of specific plant species adapted to high nutrient soil conditions. This system of vermicomposting is largely ignored in the scientific literature because of the perception that burrowing earthworm species are only suitable to agroecosystems and not vermicomposting (Slocum, 1999b). This method has not been scientifically trialed in Australia and therefore, is an unknown quantity with respect to on-site mid-scale vermicomposting. Although, Butt (1993) successfully used the burrowing earthworm Lumbricus terrestris for soil ameriolation, it has also been used to treat solid paper mill sludge and spent brewery yeast.

8.4 Variables in Vermicomposting Vermicomposting is a biooxidation and stabilisation process of organic material that involves the joint action of earthworms and microorganisms. The earthworms turn, fragment and aerate the organic matter in a vermicomposting system (Dominguez et al, 1997a). There are several key variables that will affect the performance of vermicomposting systems. These include: management and maintenance; environmental

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conditions; feedstock variables; loading rate; carrying capacity; and, processing capacity. These variables are identified below in section 7.5. Other variables will determine the size and type of the vermicomposting system utilised. These include: square metre surface feeding area; bed depth; inputs; outputs; stabilisation of castings; and, transferability between scales. These other variables are identified below in section 7.6.

8.5 Key Variables in Vermicomposting 8.5.1 Management/Maintenance Management/maintenance is of crucial importance in the operation of vermicomposting facilities (Subler, 1999). It is however, a variable that is addressed, all too regularly, in a superficial manner and the failure of vermicomposting systems can often be traced to inadequacies in the systems management. “Tossing” the bedding, the process of loosening and aerating bedding without turning or burying food, is rarely considered in the management of vermicomposting units. This method helps to aerate the substrates and maximise oxygen penetration. Without oxygen, a vermicompost unit should not exceed an absolute maximum depth of 450 mm, or compaction will be a problem. Compaction effects the efficiency of the system through a lack of oxygen and will ultimately have an effect on the optimum carrying capacity. This issue of maintenance is largely neglected in the literature and by practitioners, limited time is usually cited as a limiting factor. Preparation of feedstocks is another time consuming aspect of maintenance. If a feedstock needs to be mixed, pre-treated, or pre-processed and this is not adequately performed, then this will impact upon the processing capacity of a vermicomposting unit. For on-site C&I mid-scale vermicomposting, the enthusiasm of an employee, or proprietor, is often a critical factor in the successful performance of a system. Staff turn over, however, is sometimes cited as the reason for the failure of some systems. Training is critically important for the implement of vermicomposting units on-site, that do not require on-going maintenance contracts to manage the system. The need for training is often mentioned as an important concept, by practitioners. The reality is however, there are very few training resources available for the novice and there are no facilities that engage best practice management courses. Maintenance contracts are expensive. Training of operators, with follow-up service is likely to be far more cost effective. The cost effectiveness of an on-site system is a combination of reduction in waste disposal fees and the potential sale of vermicompost products. is a factor that may influence decisions to implement on-site remediation through mid-scale vermicomposting. Another management issue for on-site (or point source remediation) is whether imports of material, such as bulking agents, are required to make a system work.

8.5.2 Environmental Conditions Temperature and moisture are the most important environmental factors in vermicomposting systems (Edwards, 1995, 1998). The optimum environmental conditions have been well researched and they are fairly similar for all composting species.

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This section focuses on Eisenia spp. and P. excavatus as the commercially available composting worm species appropriate to temperate areas, including the Greater Sydney Region (see section 5.3).

Temperature Temperatures referred to relate to temperature of substrate, or bedding mass, not to ambient air temperature. The decomposition of organic matter will heat up a system from the metabolic processes of microorganisms. Earthworms aid and abet the increase of heat to foster microorganism activity and further increasing this activity with the exponential increase of microorganism populations in their castings (Edwards and Bohlen, 1996). Earthworm activity can also enables a system to aerate and release heat (up to a maximum bedding depth). It has been observed for P. excavatus, that as the vermicomposting system approaches 30˚C, growth and sexual maturity accelerate, cocoon incubation times shorten and hatching success increases, although, reproduction is highest at 25˚C (Edwards et al, 1998). A balanced vermicomposting system is usually 15-25˚C. The optimum temperature for Eisenia spp. is generally regarded as 20˚C (Edwards, 1998b), although, E. fetida has the broadest temperature tolerance (Reinecke et al, 1992). Constant temperatures above 30˚C are deadly for all species of composting earthworms. Earthworm activity will increase up to 30˚C and E. fetida has been observed to survive for short periods up to 45˚C (Reinecke et al, 1992), but from this temperature and above thermophilic composting is optimised. Surface area to volume ratio will also play a role in heating up a system. The larger the system, the lower is the surface area to volume ratio to allow the microbial heat to dissipate. This is one of the advantages of continuous flow and tray systems because they have a larger surface area to allow heat to dissipate. The literature suggests optimum temperatures for bedding mass in on-site vermiculture systems will vary within the 20°C – 30°C range, depending upon the species or variety of compost worm species employed.

Moisture Compost worms require a moist environment to move through substrates and prevent dehydration. Excess moisture may cause the system to become anaerobic and too little may cause dehydration of compost worm stock. Compost worms can function in moisture's as low as 40%. The optimum range of moisture for: E. andrei is 80-90% and best growth is achieved at 85% (Dominguez and Edwards, 1997); E. fetida is 70-80% (Venter and Reinecke, 1988); and, P. excavatus is 76-83% (Hallatt et al, 1990). The literature suggests 80% moisture level is recommended as the optimum moisture levels for systems of mixed worm stock appropriate for temperate environments.

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Aeration and Structure Worms absorb oxygen through their skin and require well oxygenated environments to enable air flow to dissipate heat and prevent anaerobic (low oxygen) conditions from developing. Good substrate structure is required to allow oxygen penetration and good moisture retention. Castings support good structure and aerobic conditions, and earthworms selectively cull anaerobic bacteria while aerating the substrate by moving through it (Doube and Brown, 1998). A depth of bedding in excess of 450 mm will influence compaction of the substrate creating a low oxygen environment and deterring earthworm activity (Edwards, 1995). Commercial worm farming literature recommends “tossing the beds”, a process of loosening the bedding substrate to aerate, without inverting materials. This process does not bury fresher waste materials, but rather seeks to retain the natural profile of the system. This process can be mechanical (more efficient, also more destructive of worm stock – suited to large scale operations), or can be engaged by hand with the aid of a garden fork for on-site and mid scale application (Wilson, 1999). Feedstocks need to exhibit a range of particle sizes to enhance surface area and oxygen penetration. Fibrous and bulky material provide structure and increase the Carbon:Nitrogen (C:N) ratio. The literature suggests bedding depth of less than or equal to 450mm is recommended as appropriate for on-site vermiculture system design. Worm farming literature suggests that, particularly at the higher end of this range of bedding depth, that vermiculture systems will benfit from periodic “tossing” of bedding for purpose of aeration.

Salt & Ammonia Salt and ammonia levels should not exceed 0.5 mg/litre. Above this level earthworm survival drops off rapidly. Ammonia is less likely to cause problems if a substrate remains below a pH of 8 because it is in the solid form of NH4+. Above a pH of 8 ammonia NH3 (aqueous ammonia) becomes prevalent and this ammonia state will cause problems if the concentrations are high (Miller, 1993). Salt and ammonia are present in high concentrations within some substrates such as sewage sludge, fish slurry, cattle sludge and pig slurry. These substrates will require pretreatment, or pre-processing, to reduce the toxic quantities of salt and/or ammonia to acceptable levels for the introduction of earthworms. Pre-treatment may involve washing salt concentrations out of a substrate and pre-processing may involve pre-composting or mixing substrates with complementary feedstocks. There is still not enough known about the effects of salt and ammonia on earthworms or best management practices to reduce the toxicity these biochemicals (Edwards, 1999). The literature suggests maintaining pH levels of less than pH8 to

pH The pH of most waste streams decreases to the acidic range as microorganisms decompose organic residues.

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All earthworm species have a fairly broad range of tolerance to pH levels between a pH of 4.5 and a pH of 9. Earthworms will operation the entire range. Edwards recommends that compost earthworms will function best in a substrate with a pH of 5.9 (Biocycle, 1998). Reinecke et al (1992) claim a pH of 7 (neutral) is optimal for P. excavatus. Murphy (1993) recommends a pH of 6.5 as suitable for compost worms. Vermicomposting units will normally shift towards a pH of 7 because earthworm castings are usually pH neutral. Mba (1989) has observed that cocoon survival is more likely to be achieved in castings than the surrounding organic matter, which, in some substrates, is completely toxic to cocoons.

Odour Odour is an indicator that the system is out of balance. It is often a sign that the system is going anaerobic because of the odours produced by anaerobic bacteria. Earthworms can remove odour from putrescible organics within 24 to 48 hours (Biocycle, 1998), presumably, by selectively culling the anaerobic bacteria (Doube and Brown, 1998).

8.5.3 Feedstock Variables Feedstock preferences Different species of worms have different feedstock preferences and this will be reflected in stocking capacity and processing capacity. Few studies have shown which feedstocks individual compost worm species prefer from typical C&I sector waste streams. Most studies have concentrated on whether earthworms will or will not process a particular feedstock. Knowledge of feedstock preferences will inform how a feedstock needs to be applied, or whether it benefits from pre-treatment, or whether a feedstock needs to be mixed and to what quantities with complementary feedstocks. Doube et al (1997) conducted food preference studies using the composting worm Lumbricus rubellus and 3 other burrowing Lumbricid earthworm species, but this trial did not apply typical C&I sector wastes, and the earthworm species involved are of questionable relevance.

Type or mix (waste stream) There are a diversity of compostable organic materials produced from C&I sector waste streams. Great diversity exists within the food waste stream alone. The composition of the wastes will impact on the processing capacity of an on-site system, and on the preprocessing methods required. With respect to this, The UNSW Green Waste technology Unit has submitted the following sub-categories for inclusion in the Australian Waste Database, specifically to support the consideration of on-site management options. Material Composition Codes from the Regional Waste Database, 1999 The RWD is an adaptation of the Australian Waste Database (Gia Underwood, Western Sydney Waste Board) MC = material composition, MDC = material description code, MDSC1C = material description sub category 1 code MC Code

Description

MTC

0

Mixed Waste

0

A

Paper

A

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MDC 0

MDSC1C 0

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B

Organic Compostable

B

Organic Compostable

B01

Organic Compostable Food

B

B01

Organic Compostable

B011

Fruit & vegetable B

B01

B011 Organic Compostable

B012

Meat & poultry B

B01

B012

Organic Compostable

B013

Fats & oils B

B01

B013

Organic Compostable

B014

Seafood (including shellfish, excluding oyster shells) B

B01

B014

Organic Compostable

B015

Recalcitrants (large bones >15mm diameter, oyster B shell, coconut shells...)

B01

B015

Organic Compostable

B016

Dairy (solid and liquid) B

B01

B016

Organic Compostable

B017

Bread, pastries & flours (including rice & corn flours) B

B01

B017

Organic Compostable

B018

Food soiled paper products (hand towels, butter B wrap...)

B01

B018

Organic Compostable

B019

Biodegradeables (cutlery, bags, polymers) B

B01

B019

Organic Compostable

B02

Organic Compostable Garden

B

B02

Organic Compostable

B021

Putrescible (grass clippings) B

B02

B021

Organic Compostable

B022

Non-woody (5mm diameter) B

B02

B023

Organic Compostable

B024

Trees / limbs (>150mm diameter) B

B02

B024

Organic Compostable

B03

Organic Compostable Other Putrescible

B

B03

Organic Compostable

C

Other Organic

C

C01

Other Organic Wood/timber

C

C01

C011

Wood furniture C

C01

C011

Other Organic

C012

pallets, packaging, offcuts C

C01

C012

Other Organic

C013

sawdust C

C01

C013

Other Organic

C014

shavings C

C01

C014

Other Organic

C015

Composite products (MDF, particleboard, plywood) C

C01

C015

Other Organic

C016

Treated timber C

C01

C016

Other Organic

Other Organic Other Organic

D

Glass

D

Glass

E

Plastic

E

Plastic

F

Ferrous

F

Ferrous

G

Nonferrous

G

Nonferrous

H

Special

H

Special

I

Earth Based

I

Earth Based

Some waste materials may be fed directly, others may require size reduction and/or mixing with bulking agent and additives to create an appropriate feedstock mixture. Most feedstocks generated from a mono-stream, or one particular type of waste material require the addition of, or mixing with, complementary materials to produce feedstocks.

Recycled Organics Unit

Literature Review of Worms in Waste Management – Volume 1

Page 29

Complementary feedstocks can be sourced from other waste materials for on site vermiculture applications (see section 8.5.3.6 below).

Quantity For on-site installations, the quantity and composition of feedstocks will firstly need to be assessed by conducting a waste audit. Then a system installed of adequate size for managing the maximum waste flow should be identified, installed, and commissioned with sufficient worm stock and bedding to process the intended entire waste flow. The determination of adequate system size depends upon the stock population capacity of the unit under managed environmental conditions, and the resident worm populations processing capacity for the specific feedstock produced. Reliable outcomes in terms of system sizing and stocking rate and installation would be derived from knowledge of: •

Stock carrying capacity per square metre (provided adequate bedding depth is continually maintained);

•

That feed is applied in an appropriate feed formula (feedstock);

•

Processing capacity per square metre surface of feeding area for given feedstock;

•

Management of environmental conditions appropriate to maintain consistent processing capacity. There is a paucity of quantitative information in the literature, and the lack of relevant information in these areas severely restricts the capacity for reliable installation and management of on-site vermiculture systems. Some documented evidence is reported in the literature, material, however such work has not been directed so as to provide information supporting on-site applications. Previous work in this area has not focused on evaluation of these on-site criteria, as such work has not focused on on-site application. The basic information required for to support the selection of on-site systems (according to quantity of waste materials requiring processing) is not currently available.

Particle size Size reduction should be considered to convert wastes into a form suitable for vermiculture application, andto increase the rate of breakdown of wastes. The smaller the particle size the more surface area available for microbial attack, and the easier it is for earthworms to ingest and grind the particles down further. A chopping, grinding, macerating, or blending process is a desirable form of pre-processing for most food waste materials for the purpose of size reduction and homogenisation. The resulting material can then be mixed with a bulking agent to produce an appropriate feedstock mix. If all particles in the feedstock mix were very small (