A New Approach to Biological Phosphorus Removal

BUILDING A WORLD OF DIFFERENCE®

TS002: Secondary Phosphorus Removal

A New Approach to Biological Phosphorus Removal J. Barnard, D. Houweling, H. Analla, M. Steichen

WEFTEC 2010

WEFTEC 2010

Overview 

Introduction



Overview of unconventional phosphorus removal



Fermentation of RAS for phosphorus removal



Fermentation of mixed liquor for phosphorus removal



Models must simulate all observations



Summary

TS002: Secondary Phosphorus Removal

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Phostrip Process - 1965

TS002: Secondary Phosphorus Removal

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Anaerobic zone formed at inlet end of aeration basin

Inefficient aeration and high oxygen demand responsible

In the late 60’s phosphorus removal was observed in high rate plug-flow plants that did not nitrify. Milbury noted that all such plants showed a release of phosphorus at the feed end TS002: Secondary Phosphorus Removal

WEFTEC 2010

Bardenpho Pilot plant (100 m3/d)

The purpose of the dead zone was to allow relative adjustments to the other zones.

TS002: Secondary Phosphorus Removal

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TS002: Secondary Phosphorus Removal

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Static Fermenter Anoxic PS T anaerobic Optional recycle

VFA

to digesters TS002: Secondary Phosphorus Removal

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Switching off Aerators - Disneyworld 6

Reedy Creek, Florida

Total P, mg/L

5 4

First Few Aerators Turned Off

3 2 1 0 Oct78

Jun80

Fe b82

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Fe b84

Oct85

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US Patent 5,603,833 POH process 1995 Several patents

Claim required a retention time of 12 to 72 hours in Stressed Zone but does not refer to sludge settling. Reference to a side-stream process for reduction of nitrates in the RAS.

TS002: Secondary Phosphorus Removal

WEFTEC 2010

Configuration proposed by Stroud et al for achieving both nitrogen and phosphorus removal 4Q Effluent

Influent AX

AER

AX

AER

Bardenpho plant Ferment

AN

AX

RAS Fermentation

TS002: Secondary Phosphorus Removal

WAS

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Conversion from Pho-strip to Phoredox with RAS fermentation Influent Wastewater Effluent Anaerobic

Aerated

Influent Wastewater

Settling Wasted Biomass

0.85 RAS

Effluent

0.15 RAS

Fermenter

Settling

Aerated

Return Biomass Lime

Stripper Return Biomass Lime Sludge

Wasted Biomass

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Configuration used by Vollertsen for BPR

Influent Effluent Anox/Aerobic 93% Anaerobic zone 7%

Return activated sludge

The main reactor consisted of channel systems for SND. 7% of the RAS was passed to a sidestream anaerobic zone with long retention. Note that VFA in the feed was lost for enhancing phosphorus removal

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BPR Operation at St Cloud MN

Under-aeration

TS002: Secondary Phosphorus Removal

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Effluent Quality for the St Cloud MN plant 2009 Effluent Nutrients in mg/L Eff CBOD5

Eff. TP

TKN EFF

NH3 EFF

30.0 25.0 20.0 15.0 10.0 5.0

TS002: Secondary Phosphorus Removal

12/1/2009

11/1/2009

10/1/2009

9/1/2009

8/1/2009

7/1/2009

6/1/2009

5/1/2009

4/1/2009

3/1/2009

2/1/2009

1/1/2009

0.0

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Mixed liquor Fermentation at Pinery Water Influent RAS Anaerobic

OFF

ON

Aerobic

Anaerobic

Anoxic

TS002: Secondary Phosphorus Removal

Phosphorus reduced form 9 mg/L to less than 0.5 mg/L , then with post chemical treatment to less than 0.03 mg/L. Overall molar ratio to Al:P is 0.5

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Mixed liquor Fermentation at Henderson NV

TS002: Secondary Phosphorus Removal

Carousel Plant Henderson NV

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TS002: Secondary Phosphorus Removal

1/ 2 5/ 010 2/ 2 5/ 010 3/ 2 5/ 010 4/ 2 5/ 010 5/ 2 5/ 010 6/ 2 5/ 010 7/ 2 5/ 010 8/ 2 5/ 010 9/ 5/ 201 10 0 / 5/ 201 11 0 5/ / 201 12 0 / 5/ 201 13 0 / 5/ 201 14 0 5/ / 201 15 0 / 5/ 201 16 0 5/ / 201 17 0 / 5/ 201 18 0 / 5/ 201 19 0 5/ / 201 20 0 / 5/ 201 21 0 / 5/ 201 22 0 5/ / 201 23 0 / 5/ 201 24 0 / 5/ 201 25 0 5/ / 201 26 0 / 5/ 201 27 0 5/ / 201 28 0 / 5/ 201 29 0 / 5/ 201 30 0 /2 01 0

5/

Phosphorus (mg/L)

WEFTEC 2010

Results from Henderson NV Ortho-P for May 2010 ANA Eft SPS SCC Final Eft

0.5

0.4

0.3

0.2

0.1

0

TS002: Secondary Phosphorus Removal

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Surface appearance of Henderson Plant

During mixing

Some hours after mixer off

TS002: Secondary Phosphorus Removal

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Fermenting Mixed Liquor Mixed Liquor In

Mixed Liquor Out

Mixed Liquor

PAO

VFA

PAO

PAO

VFA Heterotrophes

PAO

PAO

In the mixed liquor fermenter, the PAO survive – the OHO are fermented to produce VFA Barnard presentation Krakow 2007 TS002: Secondary Phosphorus Removal

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MJHB – UMIF Strategy We propose that this be formalized in design to create an upflow mixed liquor fermenter attached to the anaerobic zone

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Application to Henderson plant

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What have we learned? 

Phosphorus removal with unconventional processes can give reliable results



Mostly such phosphorus removal happened by manipulation or full-scale experimentation and not by design



There are too many unknowns for a lawyer-free design 

Role of nitrates



Role of influent rbCOD



Solids retention time under fermentation



Portion of the mixed liquor that can be fermented



Temperature TS002: Secondary Phosphorus Removal

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What is needed 

A better understanding of mechanisms at play



Optimizing the configuration



Consider side stream fermentation of mixed liquor as opposed to RAS



Remove the chance aspect and have more control



Model the performance of these plants in order to design with confidence TS002: Secondary Phosphorus Removal

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Challenge to the Proprietors of Simulation Models 

Efforts to model unusual phosphorus removal configurations were at first, not successful



It may be necessary to change the basic structure of models to allow for the survival of the PAO



Attend follow up paper on Wednesday by Dwight Houweling for discussion on model application

TS002: Secondary Phosphorus Removal

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Modeling the pilot plant flow diagram

TS002: Secondary Phosphorus Removal

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Conclusion 

Plants with some form of internal fermentation of mixed liquor or RAS can result in reliable biological phosphorus removal – There seems to be consensus that less than 10% of the return sludge should be fermented.



Plants that do not remove phosphorus reliably can be improved by manipulating aeration



Future designs should optimize the configuration to make maximum use of internal fermentation of mixed liquor



Fermentation of mixed liquor as opposed to RAS seem to be superior especially in plants with no primaries



Efforts are under way to establish if UMIF can replace primary sludge fermenters or allow the products to be used for denitrification.

TS002: Secondary Phosphorus Removal

WEFTEC 2010

TS002: Secondary Phosphorus Removal