Enhanced Chemical Treatment Calms Perfect Storm of Odor Conditions

ABSTRACT

The City of Tolleson, Arizona operates a 44.7 cubic meter per hour (m3/hr) [17 million gallon per day (mgd)] capacity, wastewater treatment plant (WWTP). Several residential and commercial developments have been built within ó kilometer of the Plant and odor complaints have increased. The Plant-wide odor control study was initiated in 2006 to determine the best long-term odor control approach. The initial results of the odor study, plus the urgency of the situation with adjacent neighborhoods, required immediate odor mitigation efforts – specifically by implementing an aggressive chemical addition program utilizing ferric chloride plus hydrogen peroxide. This chemical combination had been tried elsewhere, and had shown considerable success in reducing odors at trickling filters preceded by primary clarifiers. The test work demonstrated that the majority of sulfide reduction and odor control is accomplished with just ferric chloride. The addition of hydrogen peroxide produced approximately 30 percent reduction in sulfide and hydrogen sulfide emissions from the trickling filters.

KEYWORDS: Sulfide, ferric chloride, hydrogen peroxide, trickling filters, odor control

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