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Effective control of chlorination and dechlorination at wastewater treatment plants using redox potential
Author(s) -
Kim Yang H.,
Hensley Robert
Publication year - 1997
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143097x125704
Subject(s) - chlorine , wastewater , chloramine , chemistry , chlorine dioxide , reduction potential , sewage treatment , environmental chemistry , redox , pulp and paper industry , waste management , environmental engineering , environmental science , inorganic chemistry , organic chemistry , engineering
The shortcomings of total chlorine residual as a measure of wastewater disinfection are discussed. The effect of pH is significant in the toxicity of chlorine compounds. Recent investigation to the formation of organic chloramines made the residual measurement technique more difficult to use in wastewater disinfection. Redox potential (or oxidation–reduction potential—ORP) is studied as an alternative way of assessing the efficacy of disinfectants through theoretical consideration and literature review. Experiments performed using wastewater samples showed that ORP is better correlated to the inactivation of coliform than total chlorine residual. Also illustrated is a case study carried out at a municipal wastewater treatment plant in California (U.S.). By replacing conventional methods for establishing chlorine and sulfur dioxide dosage with a system that automatically modulates chemical feed by ORP, the plant reduced chemical use for chlorination and dechlorination by 47 and 62%, respectively, while consistently maintaining compliance with stringent disinfection requirements (2.2 MPN coliform per 100 mL) and chlorine discharge limits (less than 0.1 mg/L).