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Report 101001 On the Effectiveness of Corona Discharge Ozone

Treatment of Wastewater Gases and VOCs

Note: When sampling for odors, it is important to remember that the actual odourant is only

a very small fraction of the air collected and must be carefully treated to ensure the quality of thesample is not compromised before analysis. Hence the sampling technique and vessel of

containment must preserve the odorous compound in its originally encountered state. The meansof analysis must be adequate to identify the characteristics of the odorous compounds. Choosing a

means of analysis will depend on whether the data required is qualitative (odor thresholds,objective preferences) or quantitative (concentration, composition).

Sampling At Ashburn, ON Sites for the treatment of gases produced from manure and wastewater

Samples NH3 ppm RNH2 ppm H2S ppm RSH ppm DMS/DMDS ppm Total Sulfides ppm

Input 1 35 110 0.7 0.6 1.1 2.6

Input 2 18 69 2.5 2.4 2.2 7.1

Input Mean 27 90 1.6 1.5 1.7 4.9

Output 1 30 10 0.5 0.25 0.9 1.7

Output 2 13 48 0.6 0.6 0.9 2.1

Output

Mean

22 29 0.55 0.43 0.9 1.9

Human Sniff Testing Done At Test Site Through Contact Chamber

At the site, an odor panel was set up by Dr. Monty Bruce, an Environmental Engineer from theUniversity of British Columbia. The odor panel tests are double-blind experiments in which people

are given measured odorous gases or non-odorous gases to sniff through a machine. As the

human nose is very sensitive (and also the ultimate test in odor control) the panel indicateswhether people would find the odors offensive or not. The odors are then diluted by the machine

to see at what levels it becomes non-offensive.

After running the tests using the contact chambers, everyone at the test site sniffed the gases

coming out of the stack with Ozone applied and without Ozone applied. Without Ozone everyone

agreed that the gases were odorous. With Ozone everyone agreed that the smell was gone.

The reductions in Amines indicated that within a number of seconds, there should have been a

very high reduction in sulphur compounds as well. With the sulphurs gone, the odors should bekilled as well. But would the odor panel agree?

After the tests came back from the UBC, the odor panel had indeed confirmed the on-site "sniff"

tests. The untreated samples required dilution rates of between 1701-3043, which is typical ofodorous substances. The Ozone treated samples were between 209-264, which is typical of non-odorous substances. As well, the treated samples actually smelled like Ozone which has an almost

antiseptic or sanitary smell.

These results are consistent with other commercial uses for Ozone. One of the major markets for

Ozone generators...is sewage lift stations. Odors at lift stations result from anaerobic processesand Ozone kills these odors quite readily.

On of the main principles in applying Ozone is to mix the Ozone with the odorous gases. This canbe accomplished in an open air facility through the use of a ventilation system that pushes

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Ozonated air across the tops of the site. The preferred method, is if the facility is enclosed,

Ozone can be added to the ventilation system at the exhaust. A "contact chamber" can also beadded to ensure adequate mixing of the air and the ozone. If the treatment is done in an open-

air facility, the Ozone Generators should be slightly oversized to compensate for a less efficient

odor/Ozone mix. If the gases are exhausted through a ventilation system, then the generatorscan be downsized accordingly.

Table of Ozone Conversions

Table 1. - Conversion of Organic Compounds By Ozone

COMPOUNDS CONVERTED TO

AmmoniaAmmonia HydroxideAromatic CompoundsAliphatic CompoundsCyanide

Ferrous IronFormaldehydeFormic AcidCarbonic AcidEthyleneManganeseMethaneNitriteOrganic Acids

SmokeSulphur Compounds (H2S)

Trichloroethylene

To Nitrogen and Water VaporTo CO2 and WaterTo CO2 and Water Vapor and OxygenTo CO2 and Water Vapor and OxygenTo Cyanate to Nitrogen and CO2

To Ferric HydroxideTo Carbonic Acid-CO2 and WaterTo Carbon Dioxide and WaterTo Carbon DioxideTo Carbon Dioxide and WaterTo Manganese Dioxide to PermanganateTo Carbon Dioxide and WaterTo NitrateTo Carbon Dioxide, Water Vapor andOxygenTo Carbon Dioxide and WaterTo Carbon Dioxide, Water, Sulphur trioxideand OxygenTo Carbon Dioxide, Water, Hydrogen

Chloride

Conclusions of Study

"Overall, the ozonation system installed... can control the emission of odor compounds. Chemical analysis ofsamples of...gases taken before and after contact with ozone indicated that levels of odorous sulfur compoundswere reduced...by the ozonation. The extent of this reduction appears dependent on the operating conditions ofthe site. Operation of the aeration fan, for example, tends to increase the volume of gases and odorouscompounds entering the treatment system, thereby lowering the efficacy of the treatment system. Increasing theamount of ozone entering the treatment system in certain cases appears to increase the extent of reduction ofreduced sulfur compounds. Further research should be undertaken to enhance understanding of this ozonationodor control system and to optimize operational conditions to increase overall reduction of odorous compoundsfrom the compost emissions.

The present study has utilized chemical analysis to test the efficacy of ozonation as a viable means of odorcontrol. The ultimate evaluation of any system for controlling or reducing odors is performed using a combinationof chemical analysis and organoleptic or odor panel assessments of the odors (Dorling, 1977; Duns et al., 2003).Relating results from chemical analysis to odor panel measurements converted to odor units is ideally the mostinformative way to quantitatively relate constituent odor target compounds to human assessment of odors....."G . D u n s , P h . D .AirChem Consulting and Research Inc.3268 S tonebrook Rd .Bright's Grove, Ontario NON 1C0

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Rooftop Contact Chambers at Ontario Test Site