George Wong-Chong
Engineers in Allison Park, PA

4537682, Aug 27, 1985

Jan 21, 1983

6/460090

George M. Wong-Chong - Allison Park PA

Environmental Research & Technology - Concord MA

C02F 312

210611

This invention provides an activated sludge process for treating wastewater containing ammonia as a contaminant and further for treating wastewater containing ammonia as a contaminant and other contaminants which may possibly be present including cyanide, thiocyanate, sulfide and/or organics, wherein the process involves treating wastewater in the presence of an appropriate microorganism population acclimated to the wastewater contaminants and their levels in the wastewater, this microorganism population including (1) nitrifying microorganisms capable of converting ammonia to nitrite, (2) optionally, nitrifying microorganisms capable of converting nitrite to nitrate, and (3) facultative microorganisms capable of denitrifying nitrite and/or nitrate by oxidizing organic material and converting nitrite and/or nitrate to free nitrogen, with the process being operated under a series of controlled conditions to ultimately achieve in the activated sludge process a microbial conversion of ammonia to nitrite and/or nitrate and then to free nitrogen. The conditions controlled in the process of this invention include control of the sludge wastage rate, hydraulic residence time, dissolved oxygen level (DO), sludge mixing rate, biological oxygen demand (BOD), pH and temperature, as described hereinafter. Optionally, (4) other microorganisms capable of converting other contaminants such as cyanide and thiocyanate to ammonia and sulfide to sulfate can also be present.