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Effects of Thiocyanate on the Formation of Free Cyanide during Chlorination and Ultraviolet Disinfection of Publicly Owned Treatment Works Secondary Effluent
Cyanide has been detected in effluent of some publicly owned treatment works (POTWs) at levels exceeding influent concentration. Thiocyanate (SCN−) is a cyanide‐related compoundencountered in most POTW influents and may be decomposed to free cyanide (CN−) under some circumstances. Effects of SCN− on the formation of cyanide during chlorination and UV disinfection were studied through a laboratory study with synthetic solutions and POTW secondary effluent. Results indicated that CN− was detected in SCN− solutions after chlorination in which the chlorine dose or reaction time was not sufficient to destroy SCN− completely, thus ensuring no residual chlorine to destroy any CN− produced. It was also found that SCN− can be broken down to yield cyanide by UV irradiation. In addition, SCN− was observed to cause significant positive error in the conventional total cyanide analysis technique involving acidic distillation and colorimetric measurement when nitrate was present in the sample.
Effects of Thiocyanate on the Formation of Free Cyanide during Chlorination and Ultraviolet Disinfection of Publicly Owned Treatment Works Secondary Effluent
Cyanide has been detected in effluent of some publicly owned treatment works (POTWs) at levels exceeding influent concentration. Thiocyanate (SCN−) is a cyanide‐related compoundencountered in most POTW influents and may be decomposed to free cyanide (CN−) under some circumstances. Effects of SCN− on the formation of cyanide during chlorination and UV disinfection were studied through a laboratory study with synthetic solutions and POTW secondary effluent. Results indicated that CN− was detected in SCN− solutions after chlorination in which the chlorine dose or reaction time was not sufficient to destroy SCN− completely, thus ensuring no residual chlorine to destroy any CN− produced. It was also found that SCN− can be broken down to yield cyanide by UV irradiation. In addition, SCN− was observed to cause significant positive error in the conventional total cyanide analysis technique involving acidic distillation and colorimetric measurement when nitrate was present in the sample.
Effects of Thiocyanate on the Formation of Free Cyanide during Chlorination and Ultraviolet Disinfection of Publicly Owned Treatment Works Secondary Effluent
Zheng, Anping (author) / Dzombak, David A. (author) / Luthy, Richard G. (author)
Water Environment Research ; 76 ; 205-212
2004-05-01
8 pages
Article (Journal)
Electronic Resource
English
| British Library Conference Proceedings | 2002