Pilot Testing of Oxygen Ionization for Odor Control at City of Fort Collins WRF Cliff Hoelscher and Ray Kemp Paul Bonnici.

Pilot Testing of Oxygen Ionization for Odor Control at City of Fort Collins WRF

Cliff Hoelscher andRay Kemp

Paul Bonnici

Reason and Purpose of Pilot Test

• Based on discussions with other installations and visit of Denver Metro Centrifuge Building the technology seemed to be a viable option for several Fort Collins WRF problem process areas

• Technology can use existing HVAC equipment and has a low capital, operations and maintenance cost compared to other alternatives.

• Ionization actually improves working environment

• To test the effectiveness of ionization on reducing odors at several Fort Collins WRF locations

• If technology is effective develop design criteria for full scale design

Summary of Ionization Technology

• Electronic ionizer or corona-discharge ionizer

• Uses high voltage (4,000 V) applied to grid to produce strong electric field

• AC power produces both negative and positive charged air molecules (bipolar)

• Can be used in conjunction with existing HVAC systems

Summary of Ionization Technology

• Liturature states 1,000 to 2,000 ion clusters (reactive oxygen clusters) are formed per cubic centimeter

• Ions have fairly short life span (seconds)

• Typically negative ions that are produced react with positive ions in air stream but positive ions also react with some elements

• “Sweet” or “Clean” smell is actually ozone (O3) that is produced…which is not desired in high quantities (< 100 ppb for 8 hours - OSHA)

Typical Complete System for Occupied Locations

Chemical Family Formula CAS # Mol Wt IE, eV(a)

Lit.(b)

ionair(c)

Acetone Ketone CH3COCH3 67-64-1 58.08 9.703 1Ammonia Inorganic NH3 7664-41-7 17.03 10.070 X GoodCarbon Disulfide Sulfide CS2 75-15-0 76.14 10.073 1Carbonyl Sulfide Sulfide COS 463-58-1 60.08 11.18 XChloroform Halogenated CHCl3 67-66-3 119.38 11.37 2Dimethylsulfide Sulfide (CH3) 2S 75-18-3 62.14 8.69 1Dimethyldisulfide C2H6S2 624-92-0 94.20 7.4Ethyl Alcohol Alcohol C2H5OH 64-17-5 46.07 10.48 GoodEthyl Benzene Aromatic C8H10 100-41-4 106.17 8.77 XHexane, n- Alkane C6H14 110-54-3 86.18 10.13 XHydrogen Sulfide Sulfide H2S 7783-06-4 34.08 10.457 X SlowlyLimonene (1-Pentene) Misc C10H16 138-86-3 136.23 8.3Methyl Ethyl Ketone (2-Butanone)

Ketone C3H8O 78-93-3 72.11 9.52 X 1

Methyl Mercaptan Mercaptan CH3SH 74-93-1 48.11 9.439 2Propyl Mercaptan, n- Mercaptan C3H8S 107-03-9 76.16 9.2Tetrachloroethylene Halogenated C2Cl4 127-18-4 165.83 9.326 XToluene Aromatic C7H8 108-88-3 92.04 8.828 X SlowlyTrichloroethylene Halogenated C2HCl3 79-01-6 131.39 9.46 X NoTrichlorofluoromethane(Freon 11)

Halogenated CCl3F 75-69-4 137.11 11.68

Trimethylbenzene, 1,2,4- Aromatic C9H12 95-63-6 120.19 8.27 XXylene, m- Aromatic C8H10 108-38-3 106.17 8.55 X Slowly 1

Ionizability of Selected Chemicals in Air Environments

Ionization System Operations and Maintenance Requirements

• Low power consumption of bulbs (watts)• Replace filter monthly or as needed• Clean Bulbs and metal sleeve and Coat

with thin coat of high temperature silicone grease quarterly or as needed.

• Replace bulbs approximately every three years ($200/bulb)

IonairIMG-E-8

(64 watts)

Bentax50-F-5

(50 watts)

Types of Bulbs

Specifying Data for Ionair® - Tubes

• Several previous articles by equipment manufactures state that 10 watts of power will condition 800 to 1,000 ft3

Drake Water Reclamation Facility Schematic

DWRF Aerial

Compound Influent Box(ppb)

Headworks Bins(ppb)

H2S > 40,000 < 3,000Methyl Mercaptan 65 3,080Dimethyl Sulfide 9 63Dimethyl Disulfide - 68Carbon Disulfide 5 33Carbonyl Sulfide 16 46DT* 4,400 16,000

* Unitless

Compounds Observed at Pilot Locations

Pilot Unit Diagram

Pilot Unit Approximate Fabrication Cost

(2) IMG-E-8 modules $ 8,000

(1) ICE/M Controller $ 1,200

(1) Galvanized Duct Section $ 1,350

(1) Fan and Motor $ 700

(1) Control Panel $ 500

Ducting $ 200

Mounting Frame $ 500

Miscellaneous $ 250

Total $12,700

Pilot Unit Setup at Influent/Diversion Structure

Pilot Unit Setup at Influent/Diversion Structure

DWRF Influent Box, No Treatment

Ion Unit Turned On

(All Bulbs On - 2200 cfm)

DWRF Influent Box

All Bulbs Off All Bulbs OnAll Bulbs

Off

2200 cfm

DWRF Influent Box

All Bulbs On All Bulbs Off

1500 cfm

DWRF Influent Box

DWRF Influent Box

All Bulbs On

1250 cfm 1000 cfm 750 cfm

DWRF Influent Box

All Bulbs On

1250 cfm

Pilot Unit Setup at Headworks

Conclusions

• Appeared to be some modest reduction in H2S in the Influent Box

• Appeared to be some modest reduction in odor in the Headworks Bin Area

• Overall reduction was less than anticipated/desired

• Additional testing necessary