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POTENTIAL FOR GENERATION OF ADDITIONAL REVENUE FROM PRODUCTS OF WASTEWATER TREATMENT Dr. Damjan Nemec (B.Sc.Chem.Eng.)

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Presentation on theme: "POTENTIAL FOR GENERATION OF ADDITIONAL REVENUE FROM PRODUCTS OF WASTEWATER TREATMENT Dr. Damjan Nemec (B.Sc.Chem.Eng.)"— Presentation transcript:

1 POTENTIAL FOR GENERATION OF ADDITIONAL REVENUE FROM PRODUCTS OF WASTEWATER TREATMENT Dr. Damjan Nemec (B.Sc.Chem.Eng.)

2 Wastewater treatment in general removing contaminants  Process of removing contaminants from collected sewage  Household sewage  Industrial sewage contaminants  Nature of contaminants:  physical (TSS)  chemical (COD)  biological (BOD) environmentally-safe effluent  Objective is to produce an environmentally-safe effluent

3 Wastewater treatment in general  Basic process steps the black sheep  Usually regarded as the black sheep of utility services  High operating costs  High operating costs and rarely appreciated by the public Preliminary (physical) Screening Grit removal Grease removal Efficiency: - TSS = -10% - COD = - 5% - BOD = - 5% Primary (physical, chem.) Sedimentation Efficiency: - TSS = -50% - COD = -20% - BOD = -20% Secondary (biological) Aeration Sedimentation Efficiency: - TSS = -95% - COD = -90% - BOD = -95% Tertiary (advanced) Nutrient removal Filtration Adsorption Disinfection Efficiency: - TSS > -99% - COD > -99% - BOD > -99%

4 Wastewater treatment in Mombasa

5 Kipevu WWTP Kizingo WWTP

6 Kipevu WWTP

7 influent effluent aeration tanks sludge thickeners screens & grit removal sludge drying beds sludge settling tanks

8  Plant capacity:  196.000 P.E. 17.100 m 3 /d9.580 kg/d BOD  Electricity consumption  Overall cost  5.606.400 kWh/a × 20 KSh/kWh = 112.128.000 KSh/a Kipevu WWTP EquipmentNo. of unitskW per unitkW totalh/ddaily (kWh)annual (kWh) Aerators16457202014.4005.256.000 Settlers41,562414452.560 Return sludge pumps451524360131.400 Excess sludge pumps255126021.900 Sludge thickeners22,552412043.800 Screw pumps215 46021.900 Washout pump144249635.040 General110 1212043.800 Total 780 15.3485.606.400

9 influent Kipevu WWTP effluent aeration tanks sludge thickeners screens & grit removal sludge drying beds sludge settling tanks

10 Digester #1Digester #2 Biogas cleaning Biogas storage Flare CHP unit Sludge Thickened sludge Biogas Biogas production from sludge

11  Nett production of electricity  7.635 - 1.455 = 6.180 kWh/d  2.255.700 kWh/a × 20 KSh/kWh = 45.114.000KSh/d(40%)  Overall investment  1.826.000 € (~ 5,3 years of payback)  41% less sludge to dispose! Biogas production from Kipevu WWTP sludge Biogas production from Kipevu WWTP sludge

12 Kipevu WWTP

13 Expanding services  Biogas plant has space for additional substrate  Food waste from hotels can be collected as extra service  ~100 hotels, ~6.500 tourists  ~0,5 kg of food waste per tourist => 3,5 t/d of energy rich waste

14 Biogas storage Flare CHP unit Food waste Digester #1Digester #2 Biogas cleaning Sludge Substrate Biogas Biogas production from sludge

15  Nett production of electricity  8.670 - 1.510 = 7.160 kWh/d  2.613.400 kWh/a × 20 KSh/kWh = 52.268.000 KSh/d(47%)  Overall investment  1.923.000 € (~ 4,8 years of payback)  37% less sludge to dispose! Biogas production from Kipevu WWTP sludge Biogas production from Kipevu WWTP sludge

16 influent Kipevu WWTP effluent aeration tanks sludge thickeners screens & grit removal sludge drying beds sludge settling tanks

17  Can be treated further with advanced methods and reused:  Urban reuse: Irrigation of public parks, landscapes and golf courses Vehicle washing and decorative water features Connecting to fire hydrants for fire protection  Industrial reuse: Cooling water Boiler make-up water Industrial process water  Agricultural reuse  Can even be purified to potable water standards! Reuse of treated water from WWTP Reuse of treated water from WWTP

18 Reuse of treated water from Kizingo WWTP Reuse of treated water from Kizingo WWTP  For irrigation of the golf course and local parks  Only filtration and disinfection required  Nutrient removal not required, their presence is beneficial!  Limited extra investment  Plant is located beneath the golf course!

19  After treatment the water is discharged into the sea  17.100 m 3 /d  Focus on cooling water requirements of the local industry  Usually the largest use of reclaimed water  High quantities and moderate quality required  Numerous petroleum refineries in the US that practice this Reuse of treated water from Kipevu WWTP Reuse of treated water from Kipevu WWTP

20 Kipevu WWTP

21  Potential treatment required for cooling water standard  Corrosion concerns (filtration) Removal of dissolved solids  Biological concerns (disinfection) Removal of microbiological organisms (may deposit on surface) Removal of nutrients (may contribute to microorganism growth)  Scaling concerns (chemical treatment) Removal of Calcium, Magnesium, Phosphate and Sulphate Reuse of treated water from Kipevu WWTP Reuse of treated water from Kipevu WWTP

22  Wastewater treatment…  …is required to protect the environment (for today and tomorrow)  …can be very expensive, especially if plants are under capacity  …plants should be maintained regularly with skilled staff  The cost pressure can be reduced…  …by “exploiting” the potential of wastewater treatment products Sludge for energy (biogas) Expanding the services to collecting other energy rich waste (tipping fees) Reuse of treated water will be gaining in importance in the coming years  Concrete results on the assessment will be made available Current conclusions

23 Thank you for your attention! damjan.nemec@gmail.com


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