1. July 2013 TECHNICAL DIRECTOR ENVIRONMENTAL APPLICATIONS OF ACCELERATORS INDUSTRY CHALLENGES – SLUDGE TREATMENT MARTIN JOLLY

2. Employee-owned company, founded in 1915. Engineering, consulting and construction. Energy Water Telecommunications Management Consulting

3. Page - 3 Water Treatment Works Sewage Treatment Works 188kWh/Ml 219kWh/Ml 191kWh/Ml 447kWh/Ml Total usage = 635GWh/a 1250Ml/d 1500Ml/d TYPICAL UK WATER COMPANY ENERGY USAGE

4. Page - 4 Water Treatment Works Sewage Treatment Works 1250Ml/d 1500Ml/d Total usage = 635GWh/a 188kWh/Ml 219kWh/Ml 191kWh/Ml 447kWh/Ml 45kWh/Ml 41kWh/Ml 81kWh/Ml Reduction 22% Total usage = 495GWh/a 30kWh/Ml 40kWh/Ml TYPICAL UK WATER COMPANY ENERGY USAGE

5. Page - 5 TYPICAL UK WATER COMPANY ENERGY USAGE 635 495 Apply significant energy saving & generation measures 1990 Baseline

6. TYPICAL SEWAGE TREATMENT WORKS Primary settlement tank Aeration tank requires air to treat sewage by oxidising BOD & Ammonia Air supplied by a blower through a network of pipes. Primary sludge SAS Digestion Biogas for electricity generation Sludge for disposal or recycling Clean effluent to river

7. DIGESTION- COVERT ORGANIC MATTER TO METHANE Nitrogen Rich Organic Matter (sewage sludge) Volatile Fatty Acids & Other Compounds Rapid (Hydrolysis) MethaneAmmonia Slow (Methano genesis) CO 2 Ammonium Bicarbonate Alkalinity (Buffering) Equilibrium is required

8. Page - 8 Sludge Biogas Power Liquors SLUDGE TREATMENT

9. Page - 9 1. Thermal Hydrolysis 2. Enzyme Hydrolysis 3.Thermophilic digestion 4. Ultrasound 5. Microsludge 6. OpenCEL 7. Cell Rupture Advanced Digestion

10. Page - 10 THE RISE OF ADVANCED DIGESTION TechnologyFirst trialFirst Full scale plant Number of full scale plants Thermal HydrolysisEarly 1990199624 Enzyme HydrolysisLate 1990s200211 Thermophilic digestion1950s1954>20 Ultrasound1990s2000>10 Microsludge200020043 OpenCEL200020071 Cell Rupture2004N/A0

11. ADVANCED DIGESTION PROCESS FLOW SHEET Liquor treatment Power out CHP Gas holder Excess biogas burner Digestion Cake Out Digested sludge dewatering Cake storage Sludge storage Sludge feed tank Advanced digestion pre- treatment Thickening Sludge In

12. 26 th January 2011B&V DescriptionUnitsExistingNew Capacity of planttds/a39 00091 000 Maximum energy production Mw3.711.5 Digester volumem3m3 60 000 Feed to digesterDry solids (%)5-611 Photo courtesy of Cambi Manchester wastewater plant

13. Page - 13 VOLATILE SOLIDS DESTRUCTION VS SLUDGE COMPOSITION Electrical & mechanical treat SAS only Heat treatment blended sludge 32 45 58 100% SAS 100% Primary

14. Page - 14 EMPIRICAL CAKE DRY SOLIDS VS VOLATILE SOLIDS Conventional treatment – 45 sites Thermal treatment – 5 sites

15. Page - 15 FEED & CAKE DRY SOLIDS All processes improve dewaterability, thermal more than others Thermal Part Thermal 6% 7% 11% 6%

16. AMMONIA CONCENTRATION IN DIGESTER Ammonia concentration in digester is a function of : 1.Feed dry solids 2.Digester performance 3.Sludge nitrogen content 4.Up to 3000mg/l ammonia compared to conventional MAD – 1000mg/l

17. LIQUORS FROM DIGESTED SLUDGE Liquors need to be treated Dewatering centrifuges used to produce a cake

18. Page - 18 High concentration of ammonia from thermal hydrolysis as digesters fed at 11% dry solids However loads from all process similar as lower flow from thermal hydrolysis dewatering LIQUOR TREATMENT

19. VALUE FOR MONEY Relative operating cost benefit to mesophilic digestion Relative capital cost to mesophilic digestion Generally, you get what you pay for, with 1 possible exception

20. StruviteStruvite: (NH4)MgPO4·6(H2O)

21. CHALLENGES Energy – Water companies need to reduce from 495GWh/year to less than 100GWh/year. Organic matter - only able to convert a maximum of 60% to methane. Nitrogen – some recovery in bulk as a natural fertiliser. Phosphorus – recovery possible but not widespread. THIS IS A RESOURCE