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

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

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

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

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

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

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

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

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

Chemical Scrubbing | Cost examples Design and scope Cost Addition Basic system (25,000m3/hr, H2S 100ppm max and 25ppm average, 99.5% eff) $250k - Inlet H2S conc 5x larger (500ppm max & 100 ppm average) +$80k +32% Up to ~25ppm inlet mercaptans and outlet <500 ouE/m3 +$30k +12% Additional acid scrubber for ammonia removal (100ppm max & 20 ppm average) +$130k +52% 2x air flowrate (50,000m3/hr), same H2S mass (50ppm max & 10ppm average) +$110k +44% 2x air flowrate (50,000m3/hr), same H2S conc (100ppm max & 20ppm average) +$160k +64%

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

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

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

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

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

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

Carbon Filters | Cost examples Design and scope Cost Change Basic system (2,000m3/hr, 10ppm H2S average, 12 months bed life) $30k - 2x bed life to 24 months +$5k +17% 1/2x bed life to 6 months -$3k -10% Additional media for mercaptans removal to <50 ouE/m3 Duty only fan (instead of duty/standby) -$7k -23% 2x air flowrate (4,000m3/hr), same H2S mass (5ppm average), 12 months bed life 2x air flowrate (4,000m3/hr), same H2S conc (10ppm average), 12 months bed life +$10k +33%

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

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

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

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

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

Bioscrubbing | Cost examples Design and scope Cost Change Basic system (2,000m3/hr, H2S 100ppm max & 20ppm average, 99.5% eff) $80k - Inlet H2S conc 5x larger (500ppm max & 100 ppm average) +$10k +13% 2x air flowrate (4,000m3/hr), same H2S conc (20ppm average) +$40k +50%

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

Odour Control Selection Matrix Design and scope Chemical scrubber Regenerable Carbon Filter Bio-scrubber Basic system cost high low medium Flexibility to varying inlet load v good moderate Design H2S removal efficiency >99.95% >99.9% >99.5% Suitable for carbon polish yes - Chemical storage and dosing no Power usage Water + effluent requirement medium, continuous low, annual Routine checks weekly monthly Operability continuous continuous to breakthrough

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

www.ergapc.com