Effect of silver in severely nitrified chloraminated bulk waters
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Chloramine has been widely used in many water utilities as a secondary disinfectant because of increased concern over disinfection by-products (DBPs) formation. However, its popularity has been affected due to microbial acceleration, which is traditionally believed to be by nitrifying organisms or their products such as nitrite and pH value which change substantially under nitrifying conditions. With the traditional belief in mind, the conventional approach to solve 'chloramine decay' was aimed at killing or flushing out nitrifiers. We have recently shown that either soluble microbial products (SMPs) released by microbes or changes in natural organic matter (NOM) characteristics under nitrified conditions could be responsible for the acceleration. With this new insight, a new control strategy was attempted by dosing silver at a concentration of 0.1 mg-Ag/L to the nitrified bulk waters obtained in a laboratory scale system. Accelerated chemical and microbial chloramine losses were significantly reduced after the addition of silver. These results are very promising for future applications.
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Sathasivan, Arumugam; Bal Krishna, K (2012)Traditionally it is believed that nitrification was solely responsible for the widely observed chloramine loss under nitrifying conditions. On the contrary, recent results have shown that an unidentified agent (soluble ...
Zhan, Weixi (2007)Chloramine as a secondary disinfectant has been widely used by many water utilities around the world especially in a distribution system requiring a longer retention time such as the 600km long Goldfield water distribution ...
Evidence of soluble microbial products accelerating chloramine decay in nitrifying bulk water samplesBal Krishna, K; Sathasivan, Arumugam; Sarker, Dipok (2012)The discovery of a microbially derived soluble product that accelerates chloramine decay is described. Nitrifying bacteria are believed to be wholly responsible for rapid chloramine loss in drinking water systems. However, ...