a new approach to biological phosphorus removal
DESCRIPTION
A New Approach to Biological Phosphorus Removal presented at WEFTEC 2010 by James Barnard, Black & Veatch; D. Houweling; H. Analla; Mark Steichen, Black & Veatch.TRANSCRIPT
BUILDING A WORLD OF DIFFERENCE®
WEFTEC 2010
TS002: Secondary Phosphorus RemovalTS002: Secondary Phosphorus Removal
J. Barnard, D. Houweling, H. Analla, M. Steichen
A New Approach to Biological Phosphorus Removal
TS002: Secondary Phosphorus Removal
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
WEFTEC 2010
Phostrip Process - 1965
TS002: Secondary Phosphorus Removal
WEFTEC 2010
Anaerobic zone formed at inlet end of aeration basin
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
Inefficient aeration and high oxygen demand
responsible
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
WEFTEC 2010
TS002: Secondary Phosphorus Removal
WEFTEC 2010
Static Fermenter
Anoxic
to digesters
anaerobic
VFAOptional recycle
PST
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WEFTEC 2010
Reedy Creek, Florida
0
1
2
3
4
5
6
Oct-78
Jun-80
Feb-82
Feb-84
Oct-85
Tota
l P, m
g/L
First FewAerators Turned Off
Switching off Aerators - Disneyworld
TS002: Secondary Phosphorus Removal
WEFTEC 2010
US Patent 5,603,833 POH process 1995
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.
Several patents
TS002: Secondary Phosphorus Removal
WEFTEC 2010
Configuration proposed by Stroud et al for achieving both nitrogen and phosphorus removal
4Q
AX
AN
AER
Ferment
AX
AX
AEREffluent
WAS
Influent
Bardenpho plant
RAS Fermentation
TS002: Secondary Phosphorus Removal
WEFTEC 2010
Conversion from Pho-strip to Phoredoxwith RAS fermentation
Aerated Settling
Effluent
Fermenter
Wasted Biomass
Return Biomass
Influent Wastewater
0.85 RAS
Anaerobic
0.15 RAS
Aerated Settling
Effluent
Stripper
WastedBiomass
Return Biomass
InfluentWastewater
Lime
LimeSludge
TS002: Secondary Phosphorus Removal
WEFTEC 2010
Configuration used by Vollertsen for BPR
Anox/Aerobic
InfluentEffluent
Anaerobic zone
7% Return activated sludge
93%
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
TS002: Secondary Phosphorus Removal
WEFTEC 2010
BPR Operation at St Cloud MN
Under-aeration
TS002: Secondary Phosphorus Removal
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Effluent Quality for the St Cloud MN plant2009 Effluent Nutrients in mg/L
0.0
5.0
10.0
15.0
20.0
25.0
30.0
1/1/
2009
2/1/
2009
3/1/
2009
4/1/
2009
5/1/
2009
6/1/
2009
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2009
8/1/
2009
9/1/
2009
10/1
/200
9
11/1
/200
9
12/1
/200
9
Eff CBOD5 Eff. TP TKN EFF NH3 EFF
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Mixed liquor Fermentation at Pinery Water
Anaerobic Anaerobic
Anoxic
OFF ON
Influent RAS
Aer
obic
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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WEFTEC 2010
Mixed liquor Fermentation at Henderson NV
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arou
selP
lant
Hen
ders
on N
V
TS002: Secondary Phosphorus Removal
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Results from Henderson NV
Ortho-P for May 2010
0
0.1
0.2
0.3
0.4
0.5
5/1/20
105/2
/2010
5/3/20
105/4
/2010
5/5/20
105/6
/2010
5/7/20
105/8
/2010
5/9/20
105/1
0/201
05/1
1/201
05/1
2/201
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3/201
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4/201
05/1
5/201
05/1
6/201
05/1
7/201
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9/201
05/2
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05/2
9/201
05/3
0/201
0
Phos
phor
us (m
g/L)
ANA Eft SPS SCC Final Eft
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WEFTEC 2010
Surface appearance of Henderson Plant
Some hours after mixer off
During mixing
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Fermenting Mixed Liquor
PAO
VFA
PAO
PAO
PAO
PAO
VFA
Mixed Liquor
Mixed Liquor OutMixed Liquor In
Heterotrophes
In the mixed liquor fermenter, the PAO survive – the OHO are fermented to produce VFA
Barnard presentation Krakow 2007
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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
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WEFTEC 2010
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
WEFTEC 2010
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
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Modeling the pilot plant flow diagram
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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 bymanipulating 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