title: Instability of biological nitrogen removal in a cokes wastewater treatment facility during summer.
abstract: Failure in nitrogen removal of cokes wastewater occurs occasionally during summer season (38 degrees C) due to the instability of nitrification process. The objective of this study was to examine why the nitrification process is unstable especially in summer. Various parameters such as pH, temperature, nutrients and pollutants were examined in batch experiments using activated sludge and wastewater obtained from a full-scale cokes wastewater treatment facility. Batch experiments showed that nitrification rate of the activated sludge was faster in summer (38 degrees C) than in spring or autumn (29 degrees C) and the toxic effects of cyanide, phenol and thiocyanate on nitrification were reduced with increasing temperature. Meanwhile, experiment using continuous reactor showed that the reduction rate in nitrification efficiency was higher at 38 degrees C than at 29 degrees C. In conclusion, the instability of full-scale nitrification process in summer might be mainly due to washing out of nitrifiers by fast growth of competitive microorganisms at higher temperature under increased concentrations of phenol and thiocyanate.
authors.affiliation: School of Environmental Science and Engineering, Department of Chemical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, South Korea.
authors.forename: Young Mo
authors.initials: YM
authors.lastname: Kim
authors.forename: Donghee
authors.initials: D
authors.lastname: Park
authors.forename: Dae Sung
authors.initials: DS
authors.lastname: Lee
authors.forename: Jong Moon
authors.initials: JM
authors.lastname: Park
mesh_terms: D001673:Biodegradation, Environmental; D019149:Bioreactors; D003077:Coke; D015386:Hazardous Substances; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D017672:Nitrogen Compounds / Q000737:chemistry*; D012621:Seasons; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D003077:Coke; D015386:Hazardous Substances; D007220:Industrial Waste; D017672:Nitrogen Compounds; D014874:Water Pollutants, Chemical