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Effectiveness of switching disinfectants for nitrification control
Author(s) -
Carrico Bree A.,
Digiano Francis A.,
Love Nancy G.,
Vikesland Peter,
Chandran Kartik,
Fiss Matt,
Zaklikowski Anna
Publication year - 2008
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.2008.tb09751.x
Subject(s) - chloramine , nitrification , disinfectant , chemistry , chlorine , oxidizing agent , ammonia , trihalomethane , environmental chemistry , pulp and paper industry , microbiology and biotechnology , biochemistry , organic chemistry , biology , nitrogen , engineering
The effectiveness of a one‐month switch from chloramines to free chlorine for control of nitrification and the consequences of this strategy were evaluated in three distribution systems. Nitrification was observed in two of the systems, and may have been influenced by greater loss of disinfectant residual in cast‐iron pipe sections. Free chlorine inhibited nitrification episodes, though evidence of nitrification was observed several months after the return to chloramines. Ammonia‐oxidizing bacteria (AOB) were found attached to pipe‐wall specimens removed from a distribution system during and at the end of the free‐chlorination period, suggesting AOB persisted during free chlorination. Consequences of disinfectant switching include breakpoint chlorination reactions that caused periods of low disinfectant residuals and increased total trihalomethane (TTHM) concentrations. The highest TTHM concentration might not be observed until long after the return to chloramines at locations with long residence time where free chlorine remains.