Water preammonization at central water treatment facilities in a large city as a way to minimize health risks

Abstract

At present chlorine compounds are widely used to disinfect water during water treatment procedures; it stimulates occurrence of toxic chlorinated organic compounds. Water preammonization with ammonia sulfate was implemented at central water treatment facilities in Arkhangelsk. Our research goal was to assess efficiency of water preammonization at central water treatment facilities in Arkhangelsk. Our research involved analyzing drinking water quality at central water treatment facilities prior to preammonization was implemented (from January 2016 to July 2017) and after it was implemented (from June 2018 to December 2019). We examined 14,674 water samples prior to water preammonization implementation and 15,165 water samples after it. Water quality was analyzed as per 19 parameters. Non-carcinogenic effects caused by exposure to chemicals in drinking water, prior to and after preammonization, were estimated basing on calculating hazard quotients and indexes. To describe examined parameters, median and 90-th percentile was used. Wilcoxon signed-rank test was applied to reveal differences between water parameters prior to and after preammonization was implemented. Water preammonization implemented at central water treatment facilities allowed improving drinking water quality at the second lifting and in distribution networks. After preammonization were implemented, aluminum concentration want down by 2.7 times at the second lifting; nitrates concentration, by 1.2 times; chloroform concentration, by 3.5 times (р<0.001). Overall microbe number went down by 1.6 times (р<0.001). After preammonization was implemented, water turbidity in distribution networks went down by 1.3 times, aluminum and chloroform concentrations fell by 1.7 and 7.3 times accordingly (р<0,001). Contribution made by chloroform into hazard indexes decreased by 10-47% after preammonization was implemented against water treatment performed according to conventional procedures (chlorination). Water preammonization allowed achieving more qualitative and efficient operating of water supply systems and operational costs reduction; it also resulted in a decrease in concentrations of adverse side products occurring due to disinfection and in achieving higher drinking water quality

Keywords

• water preammonization
• ammonia sulfate
• water treatment
• disinfection products
• chlorinated organic compounds
• chloroform
• drinking water quality
• central water treatment facilities