Water Treatment
ongoing development, resulting in cost-effective and robust operation. Using little more than an oxygen separator, a corona discharge chamber and some compressors and other electrical components, onsite generation of ozone is relatively simple and safe. This is in sharp contrast to most other treatments that are currently commercially available. Because of the way ozone is produced, oxygen is necessarily going to be part of the treatment gas mixture when using ozone. This is beneficial becauseoxygen is also an oxidizing agent. Oxygen reacts more slowly than does ozone but is an excellent complement to it. Aside from its ability to assist in oxidation, its primary benefit is increasing the dissolved oxygen (DO) concentration of the wastewater, encouraging the growth of aerobic bacteria, which do not create compounds that are odorous, corrosive or otherwise harmful to collection systems. It also eliminates the ability of SRB to produce sulfides, either
by removing the SRB entirely or promoting the growth of aerobic species that will oxidize any sulfides before they are able to enter the wastewater stream.3
Combined use of oxygen and ozone for treatment In terms of a robust and green method ofthe treatment and prevention of odour and corrosion in collections systems, the combined forces of oxygen and ozone are at the top of the list. Oxygen is, of course, readily available, making up roughly 21 per cent of the atmosphere, and as has already been seen, is easily converted to ozone. The generation and infusion of these two gases into wastewater collection systems has proven to be a clean, safe and cost-effective
treatment.The first method of action is the powerful destructive effects of ozone on H2
S,
quickly converting it to sulfites and sulfates on contact. In addition, ozone’s antimicrobial properties can help to reduce the presence of SRB and other microorganisms
present on pipe walls while oxygen is generated as a product of this reaction. This in turn adds more power to the oxygen portion of the treatment gas mixture, which provides secondary treatment by significantly increasing DO, and allows for more complete utilization of infused treatment gases. Oxygen will also oxidize H2
S,
but at a much slower rate than ozone does. Because of these indiscriminate and powerful oxidizing characteristics, concern is sometimes raised regarding the possibility of ozone attacking the wastewater infrastructure itself. This is unlikely to occur in application, especially in wastewater where liquid-phase infusion is implemented. This is due to the high ratio of liquid volume compared to pipe surface area per unit pipe length and the extreme availability of reactants in the liquid portion.
REFERENCES 1. American Society of Civil Engineers, “ASCE’s Infrastructure Report Card,”ASCE,2009, http://www.
www.chemicalsknowledgehub.com
infrastructurereportcard.org/. 2. A. Matthews et al, “Control of Hydrogen Sulfide Buildup in Force mains using Ozone and Oxygen,” Proceedings of the Water Environment Federation, WEFTEC 2010: Session 101 to Session 112, pp. 7591- 7611(21),2010. 3. U.S. Environmental Protection Agency, “Odor and Corrosion Control in Sanitary Sewerage Systems and Treatment Plants,” Design Manual, EPA/625/1-85/018, Cincinnati, OH,1985. 4. Beltran, F.J., “Ozone Reaction Kinetics for Water and Wastewater Systems,” Lewis Publishers, 2004. 5. Lenntech, “Water Disinfection Application Standards (For EU),” 1998,
www.lenntech.com. 6. Drago, J.A. et al, “Municipal Wastewater Ozonation Practice in the United States: Past, Present and Future,” Ozone: Science & Engineering, Volume 32, Issue 1, pp. 43-55,2010. 7. Plasma Technics, Inc., “Plasma Block Product Line, Product Detail,”2011, www.
plasmatechnics.com. 8. Terry, P.A., “Application of Ozone and Oxygen to Reduce Chemical Oxygen Demand and Hydrogen Sulfide from a Recovered Paper Processing Plant,” International Journal ofChemical Engineering, Volume 2010, Article ID 250235,2010.
Further information T: +1 760 476-9090 E:
info@anuewater.com.
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