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Unlocking Resource Recovery at the Neuse River RRF with THP
NC AWWA-WEA Annual Conference
November 14, 2016
T.J. Lynch, City of RaleighAaron Brower, City of RaleighTim Woody, City of RaleighMichael Bullard, Hazen and SawyerAmy Hanna, Hazen and Sawyer
Neuse River Resource Recovery Facility
• Currently expanding from 60 mgd to 75 mgd
• Planning for expansion to 90 mgd (~ 2040)
• Aerobic digestion and lime stabilization onsite
• Composting offsite
Offsite Composting
Current Biosolids Outlets
Class B LiquidRaleigh Plus
Drivers for Change
Drivers for Change
• Age of Equipment
• Uncertainty of future Class B land application
Drivers for Change
• A strategic part of the City’s Climate Energy Action Plan
• Make enough digester gas to fuel over 3,000 passenger vehicles!
Decision to Convert to Anaerobic Digestion
• Covered and Uncovered Aerobic Digesters• 2.6 million KWhr/yr
Technology Evaluation
Technology Evaluation
Drivers for Change – Benefits of THP
Anaerobic digester volume ↓ Capital Cost ↓
Biogas production ↑ Revenue ↑
Volatile solids reduction ↑ and dry mass ↓ Hauling Cost ↓
Final cake solids ↑ Hauling Cost ↓
Low odor, Class A product Public Health ↑Environment ↑
Project Description
Thermal Hydrolysis Process (THP)
• A sludge “pressure cooker” operating at about 330F/165C (90 psig)
THP Benefits and Considerations
BENEFITS
• Decreased digester volume
• Increased biogas production
• Increased VSR
• High quality biosolids• Class A • Low odor
CONSIDERATIONS
• Stronger sidestream• Nitrogen• Phosphorus• COD
• Possible impacts to UVT• Pre-conditioning required• Sludge cooling• Rapid Volume Expansion
Proposed Biosolids Process
EQ
CLASS A CAKE STORAGE
FOG RECEIVING
SCREENINGS
LOW PRESSURE
GAS STORAGE
PS
SLUDGE SCREENS
SCREENED SLUDGE WET
WELL
PRE-DEWATERINGTHERMAL
HYDROLYSIS
COOLING SYSTEM
ANAEROBIC DIGESTERS
SLUDGESTORAGE
FINAL DEWATERING
SIDESTREAM NITROGEN REMOVAL
THICKENING
GAS CLEAN UP
BIOGAS
BOILERS
STEAM
RETURN TO HEAD OF PLANT
WAS
BLEND TANK
CAKEBIN
RNG PIPELINE INJECTION
SCREENINGS
PASTEURIZATION
TWAS
STEAM FROM BOILERS
FLARE
Sidestream Considerations
• Improved VSR across digestion increases nutrient mass loadings in the sidestream. (+20%)
• Deammonification offers a reduced energy and reduce carbon pathway for nitrogen removal.
• Dilution will be required with post-THP centrate because of toxicity and nutrient loading
Fats, Oils and Grease
Benefits of Co-Digestion
• Boost biogas production
• Divert waste from collection system
• Revenue
Market study of grease interceptor waste
• 2015: 30,000 gal/day, 2040: 60,000 gal/day
FOG
Co-DigestStorePasteurizeScreenReceive
Digester Gas Utilization
Project Benefits
Net Energy Production with Renewable Natural Gas
2+ MW hr/hr
CWSRF Green Reserve$50M @ 0%
MW
hr/
hr
0
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
Resid
uals
Disp
osed
, DT/
yr
Current THP + MAD
THP reduces residuals mass for final disposal
NRRRF will reduce operating costs with THP
$-
$50
$100
$150
$200
$250
20-y
r NPV
Ope
ratin
g Co
sts a
nd R
even
ue (
$M, 2
016$
)
Current THP + MAD
Disposal Cost Labor Cost Maintenance Cost Operation Cost Revenue
Next Steps
• In detailed design
• Selecting CMAR Contractor
• Construction to begin Q3 2017
Thank You!