1. 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

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

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
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%

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. 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

13. Technologies | Carbon Dry Media
Used for treating
Small air flows from wet wells, pumping stations – flowrates approx ,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
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%

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

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
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%

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
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

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