Prevention and Control Strategies for Nitrification Elimination in Singapore’s Drinking Water Distribution System

Many utilities that use chloramine as the water disinfectant face problem of nitrification. The employment of chloramine may degrade water quality in the distribution system. A challenge for the utilities is the control of nitrification due to the ambient temperature which is considered more optimal for growth of nitrifiers. Traditional nitrification-control strategies (such as high pH and chlorination) are not always useful and may create other water quality or operational problems. For example, many utilities must free-chlorinate the distribution system ever so often to handle the nitrification water quality problems but by so doing defeat the purpose of chloramination. In addition, occasional chlorination is not an effective long-term strategy because of very minor improvement observed. Due to the conversion of chlorination to chloramination recently, there is an urgent need to develop an indicator which can predict the nitrification potential and prevention and control strategies for nitrification which suit best the local operational, environmental and water quality conditions.

PUB and NUS have started a nitrification study in Singapore drinking water distribution system in May 07.This study aims to propose an indicator through in-depth study on the nitrification mechanisms. The indicator proposed will be used by the local utility to assess the nitrification potential. This study also aims to evaluate the potential control strategies and find suitable control strategies for the local water distribution system. The proposed control protocol will be used by the local utility to eliminate nitrification when it occurs.

Last updated on 2 Sep 2010