Modeling cyanogen chloride kinetics in distribution systems: A semi-batch C center dot t protocol for natural waters

Experiments were undertaken with the primary objective of developing kineti c relationships for the formation of cyanogen chloride (CNC1), which could then be integrated into a multi-constituent water quality model. The use of ozone in combination with monochloramine has been reported in the literatu re to enhance CNC1 formation. A procedure to determine C . t, a surrogate u sed to estimate the level of microbial inactivation achieved, was also deve loped using a semi-batch methodology. Water collected from the Mannheim Wat er Treatment Plant (WTP) (Waterloo, Ontario, Canada) at 7 degreesC and 20 d egreesC was ozonated using a semi-batch procedure to achieve a desired leve l of inactivation. A series of specific steps were then followed to simulat e treatment at the Mannheim WTP as closely as possible at bench-scale. Thre e different levels of microbial inactivation were selected to simulate 0.5- log Giardia inactivation, and both 1.0-log and 3.0-log Cryptosporidium inac tivation. Kinetic relationships were developed which described CNC1 formati on as a function of log Cryptosporidium inactivation, monochloramine concen tration, and time. It was concluded that CNC1 formation followed an exponen tial function of time that depended on both monochloramine concentration an d microbial inactivation level.