Introduction to Odour Control Technologies

1. Introduction to Odour Control Technologies Factors affecting technology selection and system cost Richard HansonMA MEng CEng MIChemE Middle East Director, ERG (Air Pollution Control) Ltd Yousif Al-ShafieBSc AMIChemE Senior Proposals Engineer, ERG (Air Pollution Control) Ltd

2. Introduction • About ERG • Specialist odour control system supplier • 30 years’ experience • UK and Middle East • About this seminar

3. Purpose of this technical seminar … is to help • end-users • consultants • main contractors to know the right questions to ask when specifying and buying odour control systems

4. Plan for technical seminar • Summary of types of odour control system • Advantages of each system and when to use each one • Factors affecting the cost of a system • Case studies and examples • Summary – selection matrix

5. Odour Control Technologies • 3 main technologies • Chemical scrubbing • Dry media (activated carbon) • Biological scrubbing

6. Treated air outlet Dosing chemicals Contaminated air inlet Purge (blowdown) Process water make-up Technologies | Chemical Scrubbing

7. Technologies | Chemical Scrubbing • Used for treating • Air from complete sewage treatment plant – air flowrate ~5,000 to >100,000 m3/hr • Mixed odour air – H2S, mercaptans, NH3, VOCs • High loadings from inlet works and sludge processing • Advantages • High efficiency scrubbing – up to >99.95% • Flexible – good turn-down on flowrate and inlet odour loading • Dosing chemicals use optimised • Suitable for carbon polishing

8. Technologies | Chemical Scrubbing • Factors affecting system size • Air flowrate  tower diameter • Inlet contaminant loading  recirc pump size & chemical usage rate • Removal efficiency  tower height • Type of contaminant  number of scrubbers

9. Chemical Scrubbing | Cost examples • Example: Basic Scrubber • Air flowrate = 25,000m3/hr • Inlet H2S conc = 100ppm max & 20 ppm average • 99.5% removal efficiency, outlet <0.5ppm • Duty/standby fans, recirculation pumps, and dosing pumps • Local ductwork • Instruments, panel and controls • Chemical storage • Approx system cost = $250,000

10. Chemical Scrubbing | Cost examples

11. Chemical Scrubbing | Operating Costs • Basic system • Power (fan + pump) = 40kW • Chemicals = 5 litre/hr 27% caustic solution = 33 litre/hr 15% bleach solution • Process water = 600 litre/hr • Effluent (to inlet PS) = 500 litre/hr • Operation staff = 0.5 days/week routine = 2-3 days/year maintenance

12. Treated air outlet Contaminated air inlet Technologies | Carbon Dry Media > 4 months – carbon spent 4 months – odour breakthrough 3 months 2 months 1 month Start – 0 months

13. Technologies | Carbon Dry Media • Used for treating • Small air flows from wet wells, pumping stations – flowrates approx 200 - 10,000m3/hr • Passive (no fan) applications • Polishing filter downstream of chemical and biological scrubbers, flowrate up to >100,000m3/hr

14. Technologies | Carbon Dry Media • Advantages • High efficiency odour control – low outlets • Simple and cost effective • Upgradeable for low outlet odour, <50 ouE/m3 • Regenerable carbon – low operating cost

15. Technologies | Carbon Dry Media • Factors affecting size • Air flowrate  vessel diameter • Inlet contaminant loading * required bed life  mass of carbon • Type of contaminant  number of media beds • Other considerations • Performance at breakthrough • Water provision and effluent disposal

16. Carbon Filters | Cost examples • Example: Basic Carbon Filter • Air flowrate = 2,000m3/hr, • Inlet H2S conc = 50ppm max & 10 ppm average • 99.5% removal efficiency, outlet <0.5ppm • Water regenerable carbon with 12 month bed life • Vessel and duty/standby fans • Local ductwork • Instruments, panel and controls • Approx system cost = $30,000

17. Carbon Filters | Cost examples

18. Carbon Filters | Operating costs • Basic system • Power (fan) = 2kW • No Chemicals • Regeneration water = 7 m3 per year • Effluent (to inlet PS) = 7 m3 per year • Carbon replacement = 450 kg every 5 years (carbon cost $2,200) • Operation staff = <0.5 days/month routine = 1-2 days/year maintenance

19. Treated air outlet Nutrient dosing Contaminated air inlet Purge (blowdown) Final effluent make-up Technologies | Bioscrubbing

20. Technologies | Bioscrubbing • Used for treating • Media air flowrate, up to ~10,000m3/hr • High loadings from inlet works and sludge processing • Advantages • Good efficiency scrubbing, up to 99%+ • No chemical storage & dosing required • Suitable for carbon polishing • Low operating and maintenance costs

21. Technologies | Bioscrubbing • Factors affecting size • Air flowrate  tower diameter • Inlet contaminant loading  purge rate • Removal efficiency  tower height • Other considerations • Response to shock loads • Operating temperature

22. Bioscrubbing | Cost examples • Example: Basic Bioscrubber • Air flowrate = 2,000m3/hr • Inlet H2S conc = 100ppm max & 20 ppm average • 99.5% removal efficiency, outlet <0.5ppm • Duty/standby fans, recirculation pumps • Local ductwork • Instruments, panel and controls • Approx system cost = $80,000

23. Bioscrubbing | Cost examples

24. Bioscrubbing | Operating costs • Basic system • Power (fan & pump) = 3kW • No Chemicals • Final effluent = 100 litre/hr • Effluent (to inlet PS) = 100 litre/hr • Media replacement = 24 m3 every ~10 years (media cost $8,000) • Operation staff = <1 days/month routine = 1-2 days/year maintenance

25. Odour Control Selection Matrix

26. Summary • Select basic type of system based on required operability and budget • System size & cost based on air flowrate and average inlet H2S load – consultant’s estimates • Add further stages of treatment for complex inlet odour and for very low outlet concentrations • Involve ERG early in project scoping decisions

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