Bio-P Removal- Principles and examples in MI and elsewhere S. Joh Kang, Ph.D., P.E. Tetra Tech, Inc. Ann Arbor, MI 2010

Presentation Outline Optimization of Chemicals and Energy Bio-P Removal - Review Examples MI and elsewhere Energy : self sufficiency in the U.S. Summary

Why are we talking about Bio-P PatMWEA? 25 years track records in MI- we started it in the cold region Sustainable system- minimal i life cycle costs: energy, chemicals, and sludge Save jobs

Reality Check- how much are we spending? At 5 MGD Plant in MI Chemicals $70,000 Chemical Sludge disposal $20,000-30,000 Electricity $200,000- $250,000 7 8 Cents /KW-Hr, average Peak demand charge Your mileage may vary

Phosphorus Removal Phosphorus removal in a WWTP is typically y a combination of BPR and CPR The goal is to incorporate influent TP into cell mass for BPR The goal is to precipitate residual soluble P with alum or ferric into a settleable solids

How Much can we save from Optimization? Electrical : 15 to 25% to begin with Chemicals : Most of them, but it depends on wastewater characteristics of your plant Sludge : ditto

Process Overview Preliminary Treatment Clarifier Filter Raw Influent Biological Process Disinfection Solids Handling Final Effluent

How do you do Remove P biologically? Cultivate Phosphorus Accumulating Organisms(PAO) Need carbon substrate- VFA Time to grow them No oxygen environment Pcan be4 6 % of cell biomass compared to 1 to 1.5% by weight

Design Considerations- wastewater characteristics Waste Characteristics : past and future CBOD 5 TSS - VSS TN / TKN TP - Ortho- P Alkalinity - Volatile acids ph COD - readily biodegradable d bl COD

To meet 1 mg/l TP by BPR, we need VFA parameters Minimum COD: TP 40-45 BOD: TP 20 rb COD: TP 10-16 VFA:TP 4-16

Volatile Fatty acids VFA P Update/VFA COD % in Wastewater Acetic Acid 0.37 60 Propionic 0.10 30 Butyric 0.12 10 for the rest isobutyric 0.14 Valeric 0.15 Isovaleric 0.24

Sources of Volatile Fatty Acids : we need 15-20 mg/l Sewers the longer, the better In-Plant Recycles : thickeners/anaerobic digesters/holding tanks Fermentation of primary sludge or RAS at the plant in new tanks a2 nd choice Commercial sources- a 3 rd choice

IF you do not have enough VFA, two options Retrofit existing thickeners or other tanks Build a new fermenter

Fermenter for Primary Sludge HRT : 6-12 hours SRT : 4 8 days 0.3 g VFA/g solids 0.06 1.5 g VFA/total solids on COD

Temperature Pontiac, MI Genesee County, MI

Secondary Release- causes and their prevention Low ph Chemical toxicity Excess anaerobic respiration/digestion Long SRT Nitrate in anaerobic zone Excessive sludge blanket

D.O. Control : manual vs. automatic control At Significant energy savings Aerobic Conditions 2.0 mg/l as low as 1.0 mg/l at peak conditions Anoxic Conditions D.O. No Nitrates Yes Anaerobic Conditions D.O. No Nitrates No

BPR Design Design to include an anaerobic zone Design HRT for anaerobic zone usually ranges from 0.5 hours to 1.5 hours DO and NOx must be exhausted to work Baffling is a common design technique Anaerobic zone is almost always the first process basin to maximize VFAs in the raw influent

Retrofit Examples in MI Pontiac, MI- First Cold Weather Demonstration in 1984-6 Genesee County, MI: Best BPR plant w/o chemical or filter Kalamazoo, MI : under construction, 2010

A/O Process: Anaerobic & aerobic zones 1 hr HRT 5 hr HRT

Genesee Co., MI, 20 MGD, AS/Land Application of Biosolids Primary Settling BPR Clarifier Storage Lime Stabilization Biosolids Land Application

Genesee County 100.0000 10.0000 Raw Influent mean = 4.45 mg/l st. dev = 0.66 mg/l COV = 15% Total Ph hosphorus, mg/l 1.0000 0.1000 Primary Effluent mean = 3.71 mg/l st. dev = 0.63 mg/l COV = 17% Final Effluent mean = 0.26 mg/l st. dev = 0.068 mg/l COV = 26% 0.0100 0.05 1 2 5 10 20 30 50 70 80 90 95 98 99.5 99.95 Percent Less Than or Equal To Raw Influent Primary Effluent Final Effluent

10 9 7 Total Phosphorus, mg/l 1 0.1 8 10 6 4 3 5 2 1 0.01 0.05 0.1 0.5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.5 99.9 99.95 Percent Less Than or Equal To 1 - Step Feed w/ Fermenter-Piscataway, MD 6- Five-stage Bardenpho-Northeast, Clearwater, FL 2 - EBPR w/ VFA Addn + Filters-Kalispell, MT 7 - Denitrification Filters + Chem Addn-Johnston Co., NC 3 - Five-stage Bardenpho-Marshall St., Clearwater, FL 8 - A/O--Genesee Co., MI 4 - A2O with VFA, chemical, and filter-durham, OR 9 - Phased Isolation Ditch-North Cary, NC 5 - Westbank--Kelowna, BC 10 - Triple sludges---western Branch, MD. Medium-Level Phosphorous Removal Plants

10 1 Total Phos sphorus, mg/l 0.1 0.01 7 4 3 2 6 5 1 0.001 0.05 0.1 0.5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.5 99.9 99.95 Percent Less Than or Equal To 1 - Chem Addn + Tert Clarifiers + Land Application-Brighton, MI 2 - Biofor, DensaDeg, and MBR-Breckenridge, CO (only Ann. Ave. and Max Month available) 3 - MBR-Lone Treek Creek, CO 4-5 Stage Bardenpho w chemical and filter, Pinery, CO 5 - Tert Clarifier + Chem Addn + Filter-McMinnville, OR 6 - MBR + Chem Addn-Hyrum, UT 7-Denite filter Lee County, FL Low Level Phosphorus Removal Plants

Brighton, MI, 1.3 MGD, OD/Filter/Land Application FeCl 3 Oxidation Ditch FeCl 3 Slow Sand Filter Land Application Clarifier Claricone Final Effluent

Typical Energy Usage in U.S. WWTPs Average Plant : 1500 KWh/Million Gallons (MG) treated for secondary treatment Advanced Treatment Plant: 2000 3000 KWh/MG

Where do we use electricity?

Is Energy Self-Sufficiency Sufficiency Feasible in the U.S.? Proven in concept and practice in Strass, Austria, a 10 MGD plant

Strass, Austria WWTP 3500000 3000000 Power Generated > Power Used 2500000 kw-hr/y year 2000000 1500000 1000000 500000 0 1992 1993 1994 1995 Power Used 1996 1997 1998 1999 2000 2001 2002 2003 Power Generated Wett, Buchauer, and Fimml, Asian Water Conference, 2007 2004 2005

Technical Features at Strass Two-stage biological process to transfer maximum amount of organic matter from liquid phase to solid phase On-line control of aeration New CHP equipment: 38% efficiency in power generation Side-stream treatment t t

Comparison of U.S. to Strass: Usage Per-person water usage is twice in the U.S. Per-person energy usage is higher than that of Strass due to: Traditional U.S. practices in design and operation Increased mixing gp power needs Increased pumping power needs Strass is more aggressive at optimization than typical US practice

Roadmap to Self- Sufficiency 100 BNR-optimization Side-Stream Treatment Automatic Controls and HVAC 50 Min Ratio 3:1 On-Line Sensors Swing Zones Turndown Capabilities Anaerobic Digestion/Co-Digestion Commitment, Regulations, Incentives and Training 0 Feasibility Study and Technology Innovation and Demonstration

Bio-gas Facts Average PE generates wastewater at 100 gpd Approx. 1 cubic foot of digester gas/d/pe via anaerobic digestion 600 BTU/c.f. 100kW of electricity it from 4.5 MGD plant

Optimization at your plant? Feasibility study Monitoring of wastewater influent and in-plant recycles Energy analysis and contracts w/utility Development of alternatives : Energy, Chemical, Sludge Funding Local or Pay as you go from savings Implementation

Pilot Demonstration? Take one train and test Convert a thickener on site Other tanks

Summary (1) Bio Phosphorus removal is proven, reliable, and efficient with fermenter. VFA is neeed from the wastewater or fermenter PAO has specific needs to grow Fermenter e design has improved Energy Optimization is a way to keep the funds at the city

Summary(2) BPR - meet the permit Saves chemical, energy and sludge management costs Environmentally sustainable operation Quality of Life is enhanced Saves jobs