1 FOG RECEIVING, PRETREATMENT AND ANAEROBIC CODIGESTION DERRY TOWNSHIP MUNICIPAL AUTHORITY CLEARWATER WWTP, HERSHEY, PA PRESENTED TO THE VWEA COLLABORATIVE BIOSOLIDS: FUEL FOR THOUGHT WORKSHOP Wayne A. Schutz Derry Township Municipal Authority May 11, 2017
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FOG RECEIVING, PRETREATMENT AND ANAEROBIC CODIGESTION
DERRY TOWNSHIP MUNICIPAL AUTHORITY CLEARWATER WWTP, HERSHEY, PA
PRESENTED TO THE VWEA COLLABORATIVE BIOSOLIDS: FUEL FOR THOUGHT WORKSHOP
Wayne A. SchutzDerry Township Municipal Authority
May 11, 2017
A. DTMA Organization & WWTP Facilities OverviewB. Hauled Wastewater [Septage] ReceivingC. Evolution & Current Handling of FOGWD. FOGW CodigestionE. BioGas Utilization
1. Steam Biosolids Dryer2. Combined Heat & Power (CHP) Facilities
F. Future Plans
PRESENTATION OVERVIEW
• Operating Authority – Staff of 36• Two Wastewater Treatment Facilities
( Includes estimated 1.2 DT/D (~14 %) from Septage / FOG Pretreatment )
WAS 2.86 32
IPF SLUDGE 1.02 11
DTMA SW WWTP 0.24 3
TOTAL 8.87 (3,238 DT/Y)
ANAEROBIC DIGESTION % REDUCTION
DIGESTED BIOSOLIDS 4.13 (1,512 DT/Y) 53
2016 SLUDGE PRODUCTION
• Septage Receiving• Started in August 1991• “If you build it they will come!”
• Current Receiving Station• Completed in 2000• Two Lane, Hauler Kiosk & DTMA Operator Station• Lime addition to settle load in primaries• Screening & Grit Removal via WWTP Headworks
HAULED WASTEWATER RECEIVING
• Originally Refused FOG Wastewaters (FOGW)• Grease was loosely define as 750 mg/l FOG
• FOGW Acceptance “Evolution”• Accepted FOGW from Derry Restaurants• Requested FOGW be diluted
FOG WASTEWATER
• Problems, Problems, & PROBLEMS • Build up of Grease on Primary Clarifier baffles, weirs, beaches & in the PC center wells.• 30 – 40 CY removed from each PC every 3 months
• Plugging Primary Sludge Line• Tear down & flush line every month
• Visible grease “specks” in digested BFP cake
FOG WASTEWATER
• Accumulation in Primary Clarifier Scum Pit• Genesis of pretreatment idea• Pilot “Digestion” in Scum Pits• Bugs, soda ash, & mixing/aeration
• Design Concept for Aerobic Grease Pretreatment• KISS• Incorporate into existing septage receiving station• Provide 48‐72 hours of detention (40,000 gal tank)• Computer controlled fill & draw
• Decant MLSS to WWTP Headworks
FOGW PRETREATMENT - GENESIS
• Final Design• Chopper Pumps (2)
• Aeration (Venturi w/ draft tube)• Mixing (floor mounted mixing nozzles)• MLSS removal via tank level controlled wasting valve
• Addition of Bacteria Delivery System• ECOBIONICS™ Biogenerator
FOGW PRETREATMENT DESIGN
BioGenerator1 System Fact SheetOperation at the DTMA AGPD
Four BioGenerators24 Hour incubation cycleDaily dose of approximately 30 trillion microbes per BioGeneratorDose at 6 AM, 12 noon, 6 PM & 12 midnight
MICROBE SELECTIONAll Class 1 Organisms (no pathogens)High Enzyme producers1. Information Courtesy of Ecobionics, a division of NCH Corporation
1. Information Courtesy of Ecobionics, a division of NCH Corporation1. Information Courtesy of Ecobionics, a division of NCH CorporationSUMMARY OF MICROBES
FOGW PRETREATMENT BACTERIA
• FOGW Pretreatment Facility• Completed in 2005• Aerated & Mixed “Batch Reactor” Tank• Fill & Draw• Lime addition for pH Control• Screening & Grit Removal via WWTP Headworks
• BUT it was/is a work in progress…..
FOGW PRETREATMENT
• Post Construction Improvements• Grinder/macerator on truck discharge to FOGW discharge connection.
• Rock trap in front of macerator.• Mixing Nozzles Modifications• Scum / Foam Control
• At optimal conditions of pH = 7 and D.O. >1.0, the foam/scum becomes problematic.
FOGW PRETREATMENT WORK IN PROGRESS
• pH Adjustment required due to VFA• Original
• Lime addition; manual control (litmus pH paper)• Too much settling
• Current• Magnesium Hydroxide addition; automatic control (pH probe)
• Immediate & Dramatic Results throughout WWTP• Within a few weeks grease buildup through out the WWTP was gone.
• Within a few months grease “specks” in biosolids cake disappeared.
• Change in delivery philosophy• Requested concentrated and if possible dedicated grease trap loads.
• “Adjusted” rates to enhance cooperation
FOGW PRETREATMENT PERFORMANCE
• No Digestion in Reactor but, pretreatment & transformation into a non‐sticking, high FOG, high VFA, MLSS
• FOGW MLSS discharged into headworks with Plant Influent for Screening & Grit Removal
• Settles out as Primary Sludge• Now “CoDigestion”
FOGW PRETREATMENT PERFORMANCE
• Anaerobic digester feed stock• High Volatiles• Very good alkalinity
• Impact of Biogas Production• Because of all the variables involved in the digestion of sludgeand the subsequent generation of methane, it is very difficult, toestablish a quantitative relationship between the amount ofgrease wastes received and the volume of methane produce, butclearly a relationship exists.
FOGW CODIGESTION
CO-DIGESTION BIOGAS PRODUCTION
MATERIAL GAS PRODUCED METHANE
( Ft3 / Lb Digested ) ( % )
Fats 20 – 25 62-72
Scum 15 – 17 70 -75
Grease 18 68
Crude Fiber 13 – 14 45 – 50
Protein 11 – 12 73Reference Buswell and Neave, 1939
IMPACT OF CODIGESTION - PRE-FOG PRETREATMENT
200,000
250,000
300,000
350,000
400,000
450,000
500,000
J F M A M J J A S O N D J F M A M J J A S O N D J F M
SCAL
E AS
NO
TED
MONTH
BIOGAS PRODUCTION vs. FOGW VOLUME ACCEPTED
BIOGAS x 10 CF
FOGW GALLONS
2004 20052003
IMPACT OF CODIGESTION - POST FOGW PRETREATMENT
200,000
250,000
300,000
350,000
400,000
450,000
500,000
550,000
600,000
650,000
M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D
SCAL
E AS
NO
TED
MONTH
BIOGAS PRODUCTION vs. FOGW VOLUME ACCEPTED
2006
BIOGAS x 10 CF
FOGW GALLONS
2008
UNIT
START-UP
2005 2007 2009
IMPACT OF CODIGESTION - CURRENT FOGW PRETREATMENT
180,000
220,000
260,000
300,000
340,000
380,000
420,000
460,000
500,000
540,000
J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D