Struvite Mitigation for Improved Bio-P Dewaterability
Struvite Mitigation for Improved Bio-P Dewaterability
CSWEA 90th Annual Meeting Eric Lynne, PE, ENV SP Bill Marten, PE, BCEE Donohue & Associates
Outline ▪ History/Background Information ▪ Donohue’s Experiences
▪ Supporting Evidence
▪ Suspected Causative Factors ▪ Current Status/Approaches
▪ Future Plans ▪ déjà vu? Page 2 | May 24, 2017 CSWEA Annual Conference
Sun Prairie WPCF BFP+Land App UCT Selector Aeration
Meso. Anaerobic Dig.
FC PC with Fermentation Sand Filter
Page 3 | May 24, 2017 CSWEA Annual Conference
Our First Hint That Something Might Be Going On – Sun Prairie (WI) WPCF ▪ Major Plant Upgrade RBC
Pilot Test = 22% TS
Bio-P
Full Scale = 18% TS
▪ Design / Construction 2005-2006 ▪ Startup 2007 Page 4 | May 24, 2017 CSWEA Annual Conference
Bio-P
%TS Cake
Currently 12-14%TS
Bio-P has its consequences…
=>
Significant Reduction in Stack Height (Kiel) Page 5 | May 24, 2017 CSWEA Annual Conference
And the List Goes On… ▪ Midwest Plants – – – –
MCES Empire / Blue Lake Beloit, WI Marquette, MI Kiel, WI
▪ HRSD – Atlantic & Nansemond Plants
▪ Metro Denver, CO A number of plants in Europe as well… Page 6 | May 24, 2017 CSWEA Annual Conference
Thoughts (Questions) to Date Has Deterioration in Dewatering Been Due to: ▪ Combination of (Bio-P WAS + Anaerobic Digestion + Dewatering) ▪ Decrease in Use of Ferric or Alum for P Removal? ▪ Sludge Volatile Content ▪ Combinations?
Page 7 | May 24, 2017 CSWEA Annual Conference
Suspected Causative Factors: Two Primary Theories 1. Bio-P Affects Sludge Extra Polymeric Substance Characteristics – Sometimes Referred to as Soluble P Theory
2. Bio-P with Anaerobic Digestion Change Makeup of Multivalent Cations in the Sludge – Often Referred to as Divalent Cation Bridging Theory
Page 8 | May 24, 2017 CSWEA Annual Conference
1. EPS – Extra Polymeric Substance Theory ▪ Bio-P Causes Differences in EPS That Impact Dewaterability of the Sludge
▪ Tied to the Soluble P Concentration of Digested Sludge ▪ Evidence that Soluble Ortho-P Binds Water to Solids – Possibly due to increased presence of EPS & that the EPS binds water that won’t release – Evidence suggests lower digested sludge soluble Ortho-P concentrations produce higher cake TS Page 9 | May 24, 2017 CSWEA Annual Conference
Recall: Bio-P Bug in the Anaerobic Digester…
Readily Biodegradable Organic Matter (VFA’s) Carbon Storage
(Energy) Polyphosphate
Page 10 | May 24, 2017 CSWEA Annual Conference
PO4 Released Into Solution Due to Cleavage of Polyphosphate Bonds
2. Divalent Cation Bridging Theory Start By Thinking About Prominent Cations in Wastewater Treatment ▪ Prominent Divalent Cations Are Mg2+, Ca2+ and Fe2+ ▪ Prominent Monovalent Cations are Na+ and K+ Ratios change with digestion/struvite Page 11 | May 24, 2017 CSWEA Annual Conference
So How Might These Affect Dewaterability?
Mg2+
Ca2+ Fe2+
Courtesy of Sprouse, 2013 Page 12 | May 24, 2017 CSWEA Annual Conference
Na+
K+
Manufacturing Industry ▪ Solutions for: – Struvite Problems – Resource Recovery – Sidestream Management – Low Level Effluent Phosphorus
Page 13 | May 24, 2017 CSWEA Annual Conference
AirPrex®
CalPrexTM
Page 14 | May 24, 2017 CSWEA Annual Conference
Airprex (see also NuReSys) ▪ Forms/Removes Struvite Before Thickening or Dewatering
Page 15 | May 24, 2017 CSWEA Annual Conference
AirPrex Pilot Data – Stevens Point (WI) 30.0% 29.0% 3-5% TS Cake Increase AND 33% Polymer Reduction
28.0%
Cake Solids (%TS)
27.0% 26.0% 25.0%
Digested AirPrex
24.0%
23.0% 22.0% 21.0% 20.0% 10.0
Page 16 | May 24, 2017 CSWEA Annual Conference
20.0
30.0
40.0 50.0 Active Polymer Dose (lb/dt)
60.0
70.0
80.0
Unfortunately, we’re still in a bit of a quandary… ▪ Is it Soluble PO4/EPS & Bound Water?
Page 17 | May 24, 2017 CSWEA Annual Conference
Unfortunately, we’re still in a bit of a quandary… ▪ Or is it Divalent/Monovalent Cation Ratio?
Page 18 | May 24, 2017 CSWEA Annual Conference
M/D Ratio Increased through AirPrex (but added MgCl2)
Whatever the actual answer, it appears struvite precipitation before dewatering helps ▪ Dewatered Cake Improvement of 2-5% TS ▪ Decreased Polymer Requirement ▪ Decreased Sidestream Phosphorus & Nitrogen Loadings ▪ Decreased Biosolids P Content – Not if only sequestered
Page 19 | May 24, 2017 CSWEA Annual Conference
Remember that Sun Prairie story…
Page 20 | May 24, 2017 CSWEA Annual Conference
21 0.60
TSTP(%) Conc. (mg/L) Effluent
20 0.50
20 0.40 19 0.30 19 0.20 18 0.10 18
Filtrate Phosphate Concentration (mg/L)
Remember that Sun Prairie story… 0.70 21 %TS Increase Sidestream Effluent Ortho-P
CSWEA 90th Annual Meeting Eric Lynne, PE, ENV SP Bill Marten, PE, BCEE Donohue & Associates
Outline ▪ History/Background Information ▪ Donohue’s Experiences
▪ Supporting Evidence
▪ Suspected Causative Factors ▪ Current Status/Approaches
▪ Future Plans ▪ déjà vu? Page 2 | May 24, 2017 CSWEA Annual Conference
Sun Prairie WPCF BFP+Land App UCT Selector Aeration
Meso. Anaerobic Dig.
FC PC with Fermentation Sand Filter
Page 3 | May 24, 2017 CSWEA Annual Conference
Our First Hint That Something Might Be Going On – Sun Prairie (WI) WPCF ▪ Major Plant Upgrade RBC
Pilot Test = 22% TS
Bio-P
Full Scale = 18% TS
▪ Design / Construction 2005-2006 ▪ Startup 2007 Page 4 | May 24, 2017 CSWEA Annual Conference
Bio-P
%TS Cake
Currently 12-14%TS
Bio-P has its consequences…
=>
Significant Reduction in Stack Height (Kiel) Page 5 | May 24, 2017 CSWEA Annual Conference
And the List Goes On… ▪ Midwest Plants – – – –
MCES Empire / Blue Lake Beloit, WI Marquette, MI Kiel, WI
▪ HRSD – Atlantic & Nansemond Plants
▪ Metro Denver, CO A number of plants in Europe as well… Page 6 | May 24, 2017 CSWEA Annual Conference
Thoughts (Questions) to Date Has Deterioration in Dewatering Been Due to: ▪ Combination of (Bio-P WAS + Anaerobic Digestion + Dewatering) ▪ Decrease in Use of Ferric or Alum for P Removal? ▪ Sludge Volatile Content ▪ Combinations?
Page 7 | May 24, 2017 CSWEA Annual Conference
Suspected Causative Factors: Two Primary Theories 1. Bio-P Affects Sludge Extra Polymeric Substance Characteristics – Sometimes Referred to as Soluble P Theory
2. Bio-P with Anaerobic Digestion Change Makeup of Multivalent Cations in the Sludge – Often Referred to as Divalent Cation Bridging Theory
Page 8 | May 24, 2017 CSWEA Annual Conference
1. EPS – Extra Polymeric Substance Theory ▪ Bio-P Causes Differences in EPS That Impact Dewaterability of the Sludge
▪ Tied to the Soluble P Concentration of Digested Sludge ▪ Evidence that Soluble Ortho-P Binds Water to Solids – Possibly due to increased presence of EPS & that the EPS binds water that won’t release – Evidence suggests lower digested sludge soluble Ortho-P concentrations produce higher cake TS Page 9 | May 24, 2017 CSWEA Annual Conference
Recall: Bio-P Bug in the Anaerobic Digester…
Readily Biodegradable Organic Matter (VFA’s) Carbon Storage
(Energy) Polyphosphate
Page 10 | May 24, 2017 CSWEA Annual Conference
PO4 Released Into Solution Due to Cleavage of Polyphosphate Bonds
2. Divalent Cation Bridging Theory Start By Thinking About Prominent Cations in Wastewater Treatment ▪ Prominent Divalent Cations Are Mg2+, Ca2+ and Fe2+ ▪ Prominent Monovalent Cations are Na+ and K+ Ratios change with digestion/struvite Page 11 | May 24, 2017 CSWEA Annual Conference
So How Might These Affect Dewaterability?
Mg2+
Ca2+ Fe2+
Courtesy of Sprouse, 2013 Page 12 | May 24, 2017 CSWEA Annual Conference
Na+
K+
Manufacturing Industry ▪ Solutions for: – Struvite Problems – Resource Recovery – Sidestream Management – Low Level Effluent Phosphorus
Page 13 | May 24, 2017 CSWEA Annual Conference
AirPrex®
CalPrexTM
Page 14 | May 24, 2017 CSWEA Annual Conference
Airprex (see also NuReSys) ▪ Forms/Removes Struvite Before Thickening or Dewatering
Page 15 | May 24, 2017 CSWEA Annual Conference
AirPrex Pilot Data – Stevens Point (WI) 30.0% 29.0% 3-5% TS Cake Increase AND 33% Polymer Reduction
28.0%
Cake Solids (%TS)
27.0% 26.0% 25.0%
Digested AirPrex
24.0%
23.0% 22.0% 21.0% 20.0% 10.0
Page 16 | May 24, 2017 CSWEA Annual Conference
20.0
30.0
40.0 50.0 Active Polymer Dose (lb/dt)
60.0
70.0
80.0
Unfortunately, we’re still in a bit of a quandary… ▪ Is it Soluble PO4/EPS & Bound Water?
Page 17 | May 24, 2017 CSWEA Annual Conference
Unfortunately, we’re still in a bit of a quandary… ▪ Or is it Divalent/Monovalent Cation Ratio?
Page 18 | May 24, 2017 CSWEA Annual Conference
M/D Ratio Increased through AirPrex (but added MgCl2)
Whatever the actual answer, it appears struvite precipitation before dewatering helps ▪ Dewatered Cake Improvement of 2-5% TS ▪ Decreased Polymer Requirement ▪ Decreased Sidestream Phosphorus & Nitrogen Loadings ▪ Decreased Biosolids P Content – Not if only sequestered
Page 19 | May 24, 2017 CSWEA Annual Conference
Remember that Sun Prairie story…
Page 20 | May 24, 2017 CSWEA Annual Conference
21 0.60
TSTP(%) Conc. (mg/L) Effluent
20 0.50
20 0.40 19 0.30 19 0.20 18 0.10 18
Filtrate Phosphate Concentration (mg/L)
Remember that Sun Prairie story… 0.70 21 %TS Increase Sidestream Effluent Ortho-P
