Pilot Testing of Oxygen Ionization for Odor Control at City of Fort Collins WRF Cliff Hoelscher and Ray 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 (O 3 ) that is produced…which is not desired in high quantities (< 100 ppb for 8 hours - OSHA)

Typical Complete System for Occupied Locations

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)

Ionair IMG-E-8 (64 watts) Bentax 50-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 ft 3

Drake Water Reclamation Facility Schematic

DWRF Aerial

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

DWRF Influent Box, No Treatment

Ion Unit Turned On (All Bulbs On cfm) DWRF Influent Box

All Bulbs Off All Bulbs On All Bulbs Off 2200 cfm DWRF Influent Box

All Bulbs OnAll Bulbs Off 1500 cfm DWRF Influent Box

All Bulbs On 1250 cfm1000 cfm750 cfm

DWRF Influent Box All Bulbs On 1250 cfm

Pilot Unit Setup at Headworks

Conclusions Appeared to be some modest reduction in H 2 S 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