WASTE SOLIDS REDUCTION TECHNOLOGIES

1. WASTE SOLIDS REDUCTION TECHNOLOGIES December 4, 2009 Timothy Shea, Ph.D., PE, BCEE, Julian Sandino, Ph.D., PE

2. Why Reduce Sludge Generation? • Reduce costs (capital and O&M) in sludge processing and ultimate disposal/reuse. • Maximize potential benefits of sludge processing (e.g. optimized energy balance in WWTP) • Reduce carbon footprint

3. Primary Treatment Secondary Treatment Headworks Plant Effluent Plant Influent Solids Handling Activated Sludge PS to Digestion WAS to Digestion Dewatering/ Disposal • Homogenization • Sonication • Thermal Hydrolysis • Thermophilic Digestion • Phased Digestion • Acid/Enzymatic Hydrolysis • Extended Aeration • Cannibal™ • Biolysis®O Secondary Enhancements

4. CannibalTM • USFilter Cannibal™ builds on the “extended aeration” concept

5. CannibalTM • Biological Solids Destruction – Continuous • cycling ML between the main plant and I/C tank • anaerobic/aerobic cycling in the I/C tank • Physical Solids Separation – Intermittent • 250-micron fine screens – organic material • Hydrocyclone units – inerts/grit material • 20 to 30 percent of the solids reduction • Solids Inventory Purging – Annual • low yield (0.1 lb TSS /lb BOD)

6. CannibalTM • Small to medium size plants (w/o anaerobic digestion …) • Major Cost Items • covered I/C tanks and appurtenances (pH and ORP meters, mixer, ) • odor control system • SSM • Recent Cost quote for Fillmore, CA (1.8 mgd): • $1.1Million USFilter supplied equipment • excludes 0.5MG concrete tank, piping, odor control, I/C tanks decanter, sludge pumps, etc.

7. CannibalTM • Advantages • waste solids reduction • processing and hauling costs reduction • integration with most AS systems possible • Disadvantages • Single vendor • more complex system • odor issues (I/C reactor and screens) • biogas value of volatile solids LOST • not applicable to conventional biological phosphorus removal systems

8. Primary Treatment Secondary Treatment Headworks Plant Effluent Plant Influent Solids Handling Activated Sludge PS to Digestion WAS to Digestion Dewatering/ Disposal • Thermal Hydrolysis • Pressure Release • Thermophilic Digestion • Phased Digestion • Acid/Enzymatic Hydrolysis • Extended Aeration • Cannibal™ • Biolysis®O Digestion Pretreatment

9. Digestion Pretreatment – Why? • Disrupt cellular/ organic material that is slower to breakdown: • Increase hydrolysis of complex organics and production of VFAs and hydrogen • Increase digestion rates & stability • Increase gas production • Increase volatile solids (VS) reduction • Reduce solids for dewatering & reuse/disposal • Reduce filamentous foaming • Reduce viscosity • Improve dewatering • Lesser value in hydrolyzing primary sludge

10. Thermal Hydrolysis: CAMBI • Origins in Norway • High pressure-high temperature process: thermal hydrolysis of dewatered sludge under pressure using live steam. • Hydrolyzed and pasteurized sludge digested at greater VSLRs (smaller vessels). • Heat recovery minimizes the energy consumption. • Application in mid-size treatment works (100 mgd capacity range) at Aberdeen, Scotland and Ringsend, Dublin.

11. 4 1 Pressure in reactor is reduced to 60 psi. Solids are dewatered Steam is returned to Pre-Heat • To ~15 % Reactor Flash Pre-Heat Tank Tank 2 5 Solids mixed with return steam and Reactor pressure is Steam Water, so about 12% 3 rapidly released,flashing solids to the flash tank. Solids are heated by Flashing causes cells to • direct steam addition to rupture o 320 F and 90 psi for Steam is returned to • 45 minutes Pre-Heat Hydrolyzed solids have reduce Class A time v. temp. • • viscosity Organic compounds are • solubilized Methane 8-10 % solids digester feed Class A biosolids • o at 1 00 F Reduced volume • >35% solids • 60 V.S. destruction • Anaerobic 60% C.O.D. conversion • Digester 50% reduction in digester volume • increased gas production • Dewatering Dewatering foaming eliminated • 30 - 37% DS 35-40% DS

12. CAMBI at Ringsend WWTP • 1,200,000 population equivalent • 40,000 dry tons per year (81%VS) • Dewatering (15%TS) • Thermal (steam) hydrolysis with heat recovery (for digesters) • Anaerobic digestion (60% VSD) Biogas co-generation w/ heat recovery • Digested sludge (50%VS) to dewatering and heat drying

13. CAMBI Claimed Performance

14. Thermal Hydrolysis • Advantages: • Enhanced VSLRs • Requires smaller digesters • Produces a Class A biosolids • Improved dewaterability of digested solids • Total destruction of microbiota from WAS, thereby reducing/eliminating foaming in digesters.

15. Thermal Hydrolysis • Disadvantages: • Process complexity (substantial contractor retrofit at Aberdeen and Ringsend). • The process requires the use of high pressure steam, a need that has not been met well in municipal treatment works in the United States. • There is considerable cost uncertainty with the process given the problems encountered.

16. Pressure Release • Macerate WAS to homogenize • Increase pressure (12 Bar) with PC pump • high pressure mixer, flow into disintegration nozzle. • As the flow exits the nozzle, cavitation occurs rupturing cell structure • Sludge can be passed through system three times before discharge to the digesters.

17. Pressure Release Vendor claims • A minimum 20% increase in Biogas production. • A minimum 15% reduction in dehydrated sludge volume • Carbon augmentation for BNR Crown Disintegrator Wiesbaden WWTP - 60m3/hr

18. Homogenization/Pressure Release - MicroSludgeTM • NaOH to weaken cell membranes and reduce viscosity (pH 9 to 10) • Chopper pump to break up agglomerates • Screen to 800 m to remove non-cellular debris • Homogenizer pressure 82,700 kPa (12,000 psig) for cell lysis

19. Questions?