Extractive Nutrient Recovery as a Green Option for Managing Phosphorus in Sidestreams and Biosolids - Wendell Khunjar, Ph.D. Ron Latimer, P.E ...
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Extractive Nutrient Recovery as a Green Option for Managing Phosphorus in Sidestreams and Biosolids Wendell Khunjar, Ph.D. Ron Latimer, P.E. Katya Bilyk, P.E. Joe Rohrbacher, P.E. Paul Pitt, Ph.D., P.E.
Agenda Sidestream treatment overview Phosphorus Removal/Recovery Options Case Study 1 - Nansemond Treatment Plant Case Study 2 – FWHWRC Case Studies 3 and 4 – Miami Dade Treatment Plants Summary MR396
Biological treatment is a cost effective, robust
option for carbon and nutrient removal
■ Biological nutrient removal uses microorganisms
To solids
handling
To solids
handling
■ Solids generated must be processed before disposal
■ Anaerobic digestion is a common solids treatment
option
MR396
Water resource reclamation facilities accumulate
nutrients within the solids process
Urine
Adapted from 67%
Cornel et al., 2009
Effluent
10%
Up to 90% of the
influent P can be
Feces
Primary
Sludge EBPR or present in the
33% 10-15% Chem - P
Secondary
Sludge
Removal
35-50%
solids stream
25-40%
Sludge
Up to 90%
Adapted from Gaseous emission
Phillips et al., 2011 Urine
67%
80%
Up to 20% of the
Effluent influent N can be
13%
present in the
Feces
solids stream
20% Sludge
20%
MR396
Solids stabilization generates nutrient rich liquid
stream
10 Treatment 20 Treatment
Fe or Alum
Disinfection
Fe or Alum
Screenings Grit
10 Sludge 20 Sludge
Effluent
■ Sidestreams are typically
returned to the head of
the plant for treatment
■ Examples of sidestream Biosolids
BFP filtrate Residual
Handling
GBT filtrate
Filter backwash
Centrate
Digester supernatant
MR396
High nutrient recycle loads can upset the
mainstream process
7/11/06 Recycle Stream
Description Sampling
Percent of Percent of
PhosphorusTotal Influent Total Influent
900 Nitrogen Phosphorus
Load Load
800 Up to 50% of the total
700 influent P load can be
present in the
Nansemond,
TP Load (lb/day)
600 Suffolk, VA 13% 29%
500
sidestream
Centrate
Bowery Bay, NYC
400 17% *
Centrate
300 Henrico County, VA
15% *
200 Centrate
100 High Point Eastside,
* 50%
NC Fermenter
0 Wards Island, NYC
Centrate 30-40%
Ash Lagoon Decant Primary* Effluent
Centrate
North Durham, Sampling
NC Location
Centrate Total P 19% 30%
South Durham, NC
21% 25%
Centrate
MR396
Struvite can be a significant maintenance concern
with anaerobic digestion
Struvite = Mg + NH4 + PO4
NH4 & PO4 released in digestion
Typically Mg limited
Mg addition (i.e. Mg(OH)2) can
promote struvite formation
NYC Newtown Creek
WPCP
Miami Dade SDWRF
MR396
Sidestream treatment is the manipulation of the
return liquid stream for a treatment purpose
Typically focused on nutrient removal or recovery
Usually economical when sidestreams contribute:
■ ≥15% of the influent TN
■ ≥20% P load
Can often reuse existing infrastructure to reduce costs
Biological mainstream process
Sidestream Anaerobic
Dewatering Thickening
treatment Digestion
Biosolids
MR396
What options are available for sidestream nutrient
treatment?
Nutrient rich Treatment Nutrient free
sidestream effluent
process
Removed/recovered
nutrient
N Removal and P removal and
recovery recovery
Nitrification/Denitrification Coagulant aided precipitation
Nitritation/Denitritation
Struvite crystallization
Deammonification
Gas stripping and/or ion
exchange
MR396
P removal from sidestreams relies on chemical
precipitation
Coagulant aided precipitation
o Uses Alum or Ferric
o Non-proprietary
o Traditionally used for controlling
sidestream P at this plant
o High O&M requirement
Struvite recovery
o Forms struvite which can be
used as a slow release fertilizer
o Proprietary
• Ostara
• MFH
• Procorp/DHV
• Paques
• Veolia
MR396Struvite recovery exploits pH dependent chemical
precipitation phenomena
Struvite precipitation
N:P ratio in struvite = 0.45 lbs N required per lb P removed
N:P ratio in filtrate ~ 2.4-2.6, ammonia in excess
Mg(NH4)PO4(s) = struvite
External External
NaOH Mg+2
Mg+2
Struvite
NH4 +-N
Recovery
Reactor
PO4-3 - P
Mg(NH4)PO4(s)
MR396Intentional struvite recovery exploits pH dependent
chemical precipitation phenomena
Fluidized bed reactor or CSTR used for struvite
recovery
Effluent
FBR N:P ratio in struvite = 0.45
lbs N required per lb P
removed
Dewatering
Struvite
Dryer
Magnesium
Caustic
Sand (Procorp)
Centrate/Filtrate
N:P ratio in filtrate ~ 2.4-2.6, ammonia in excess
MR396There are several commercial options for struvite
recovery
Multiform
Name of
Ostara Pearl® Harvest struvite Phospaq Crystalactor® NuReSys
Technology
technology
Struvite,
Name of product
Crystal Green ® struvite fertilizer struvite fertilizer Calcium‐phosphate, BioStru®
recovered
Magnesium‐phosphate
% efficiency of
80-90% P 80-90% P 80% P 85-95% P >80% P
recovery from
10-40% NH3-N 10-40% NH3-N 10-40% NH3-N 10-40% NH3-N 5-20% N
sidestream
Product Third party facilitated by
Ostara Multiform Harvest N/A N/A
marketing/resale Procorp
# of full-scale
installations in 8 2 2 4 7
design/operation
MR396Nansemond Treatment Plant is a 30 MGD facility that
employs a 5-stage BNR for N and P removal
Nansemond –
HRSD, Virginia
TN = 8
• 30 MGD BNR –5
mg/L
Stage
TP = 1
• 8 mg TN/L mg/L
• 1 mg TP/L
MR396Nansemond Treatment Plant is a 30 MGD facility that
employs a 5-stage BNR for N and P removal
Diurnal Sampling
16.00
TN = 8
Sidestream load mg/L
14.00 represents up to
30% of the plant TP = 1
mg/L
12.00
influent P load
10.00
TP (mg/L)
8.00
6.00
4.00 Day 1 Influent TP
Day 2 Influent TP
Day 1 PE TP
2.00 Day 2 PE TP
0.00
12:00 AM 2:00 am 4:00 am 6:00 am 8:00 AM 9:00 AM 12:00 PM 2:00 PM 4:00 pm 6:00 pm 8:00 pm 10:00 pm
Time
MR396Two options were considered for sidestream P
Treatment at NTP
Ferric addition
o Forms ferric phosphate and ferric
hydroxide
o Non-proprietary
o Traditionally used for controlling
sidestream P at this plant
o High O&M requirement
Struvite recovery
o Ostara Pearl
o Treatment fee option
o OSTARA provides facility
and HRSD pays fee for use
o Capital purchase option
o NTP purchases equipment
and receives annual
payments from OSTARA
MR396Net present worth analyses indicated that the capital
purchase option was the most cost-effective solution
Treatment Fee Capital Purchase
Item
Option Option
Ferric Chloride Chemical Cost $ (290,000) $ (290,000)
Sludge Savings $ (155,000) $ (155,000)
Methanol Savings $ (29,000) $ (29,000)
Oxygen Savings $ (19,000) $ (19,000)
Ostara Paybacks $ (87,850) $ (135,850)
Total Annual Savings $ (580,850) $ (628,850)
Caustic Cost Allowance $ 25,000 $ 25,000
Ostara Annual Fee $ 444,000 $ -
Total Annual Operating Cost $ 469,000 $ 25,000
Nutrient recovery option was more cost effective than
Total Capital Cost $ 1,080,000 $ 4,143,000
Ferric addition option
Present Worth Operating Costs $ (1,505,750) $ (8,129,160)
Net Present Worth5 $ (425,750) $ (3,986,050)
Present worth cost of line 10 over 20 years at 5% cost of financing
MR396NTP constructed and has operated the nutrient recovery facility for ~ 2 years MR396
Full scale struvite recovery facility at NTP
System has produced ~ 1100 lb struvite/day
MR396The struvite recovery facility has reduced ortho-P
concentrations by approximately 85%
Inf.& Eff. Ortho-P and % Removal for Ostara
Influent ortho-P to Ostara Average Eff. ortho-P
% ortho-P Removal 7 per. Mov. Avg. (Influent ortho-P to Ostara)
7 per. Mov. Avg. (Average Eff. ortho-P) 7 per. Mov. Avg. (% ortho-P Removal)
1000 100%
900 90%
800 80%
700 70%
Concentration mg/L
Percent Removal
600 60%
500 50%
400 40%
300 30%
200 20%
100 10%
0 0%
May-10 Aug-10 Nov-10 Mar-11 Jun-11 Sep-11 Dec-11 Apr-12 Jul-12 Oct-12 Jan-13 May-13
MR396Ammonia removal has averaged 25%
Inf and Eff Ammonia and % Removal for Ostara
Influent Ammonia to Ostara Average Eff. Ammonia from Ostara
% Ammonia Removal 7 per. Mov. Avg. (Influent Ammonia to Ostara)
7 per. Mov. Avg. (Average Eff. Ammonia from Ostara) 7 per. Mov. Avg. (% Ammonia Removal)
1000 100%
900 90%
800 80%
700 70%
Concentration mg/L
Percent Removal
600 60%
500 50%
400 40%
300 30%
200 20%
100 10%
0 0%
Jan-11 Mar-11 Jun-11 Aug-11 Nov-11 Feb-12 Apr-12 Jul-12 Oct-12 Dec-12 Mar-13 May-13
MR396F. Wayne Hill Water Reclamation Center
• Gwinnett County, GA
• 60 MGD advanced WWTP
• 0.08 mg/L TP effluent limit
• Bio-P and chemical trim for P-removal
MR396In 2009, F. Wayne Hill Changed from Bioxide to
Mg(OH)2 in Collection System for Odor Control
Pros: Eliminated need for ALK addition at plant
Cons: Struvite formation in centrate lines, centrifuges, digester
complex
Sludge from 22 mgd Yellow River Bio-P plant coming, which
would substantially increase P load in sidestreams and SFP
MR396 Struvite taken from centrifugeLimiting effluent P and struvite formation are key
drivers for this plant
Phosphorus outlets:
o Effluent (Limit TP = 0.08 mg/L)
o Sludge cake (precipitated complex, biomass, struvite)
o Struvite solids from nuisance formation
Study goal: determine best solution for struvite
issue (Mg continues) or P recycle issue (Mg stops)
o Nutrient Recovery
o Metal salts
MR396Five options were considered for sidestream P
removal from F. Wayne Hill AWRF
Do Nothing
Ferric addition with and without
Mg(OH)2 addition
Struvite recovery with and without
WASStripTM
MR396WASSTRIP™ concept minimizes nuisance struvite
production
Send P rich sidestream to recovery process
Release P
from sludge
using VFA
rich stream
Low P content of
sludge minimizes
nuisance struvite
formation from
digester onwards
MR396Bench scale testing of the WASSTRIP™ process
was performed
Determine levels and rates of PO4 release from WAS
Optimize parameters to maximize PO4 release in
pilot studies
o Anaerobic retention time and WAS:PS blend ratio
MR396Using the pilot data, Biowin™ process modeling was
used to simulate each alternative
1. Use calibrated whole plant model to simulate alternatives at each flow
scenario
2. “Do Nothing” scenario is modeled for comparison of struvite formation
3. The modeling results were used to assess effectiveness of the nutrient
control strategy and also to estimate costs for the BCE.
Raw INF
Grit tank
YR Sludge
Grit
BRB 5-10- A2 BRB 5-10- B1 BRB 5-10- B2 BRB 5-10- C3+C4 BRB 5-10- C5+C6BRB 5-10- C7
BRB 5-10- C1+C2 BRB 5-10- C8
BRB 5-10- A1
Tertiary Clarifier Metal Salt
Tertiary Caustic
Influent (SV)7
P release Sec Scum
Combined Filter Effluent - Pre
Influent (SV)17
Anaerobic Digesters Bioreactor21
Dewatered Sludge
Influent (SV)51
Bioreactor33
OSTARA struvite
MR396P recovery provides equivalent struvite reduction
compared with the ferric addition option
14,000
30 mgd
12,000 40 mgd
50 mgd
10,000
PPD of Struvite in Sludge Cake
8,000
6,000
4,000
2,000
0
Do Nothing Ostara + Ostara + Ostara Ferric Ferric
WASSTRIP + WASSTRIP + Centrate Digesters Centrate
Mag No Mag No Mag Mag No Mag
Scenario
MR396Struvite recovery + WASSTRIP has lowest net
present cost and 8-Year Payback
$25.0
Ostara + WASSTRIP, Mag
Ostara + WASSTRIP, No Mag
$20.0 Ostara Centrate, No Mag
Ferric Digesters, Mag
Ferric Centrate, No Mag
$15.0
NPC, $ Millions
$10.0
$5.0
$0.0
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
Year
FWHWRC is pursuing nutrient recovery option
MR396Miami-Dade resource recovery
■ Pure oxygen facilities
■ Meets secondary treatment standards
■ Disposal through deep injection wells
■ Significant
nuisance struvite
CDWWTP – 143 mgd formation issue
AADF
SDWWTP – 112.5 mgd
AADF
MR396Miami Dade resource recovery - evaluations
In-situ Coupon Testing to Bench Scale Testing to
Determine Degree of Struvite Determine Optimal Ferric Dose
Formation and Confirm
Theoretical Ferric Dose
Modeled Struvite Potential and Ostara
Reduction for Each Alternative Pilot Test
MR396
& Performed Cost EvaluationNutrient Recovery was the most cost effective
option at both plants
Notes: * 6% interest and escalation
** Could be significantly higher
Long term recommendation is to implement nutrient
recovery at both facilities
MR396Summary
1. Reduce energy and chemical consumption
clarificatio
in the mainstream process n
2. Provide factor of safety for mainstream
nutrient removal process
To
mainstream 3. Minimize nuisance struvite formation and
reduce O&M costs
Sidestream Anaerobic
Dewatering Thickening
treatment Digestion
1. Manipulate the nutrient content of the
Biosolids biosolids
2. Provide plant with alternative revenue
stream
MR396Summary
Compare struvite crystallization with precipitation with
coagulant (i.e., alum or ferric)
Payback site-specific and dependent on the P load
Tool for Evaluating Resource RecoverY (TERRY)
developed through WERF grant to help facilities perform
high level evaluation for implementing P recovery
MR396Contact Information
Wendell O. Khunjar, PhD
4035 Ridge Top Road, Suite 400, Fairfax VA 22030
703 267-2759 (direct) | wkhunjar@hazenandsawyer.com
Katya Bilyk
4011 Westchase Blvd., Suite 500, Raleigh, NC 27607
Phone: 919-755-8593| kbilyk@hazenandsawyer.com
Ron J. Latimer, PE
5775 Peachtree Dunwoody Rd. Suite D-520, Atlanta, GA
30342
404-459-6363 (main) | rlatimer@hazenandsawyer.com
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