Impacts of salinity on treatment efficiency of surface water in coastal areas

Abstract

Currently, surface water has become the main water source for domestic water supply in Vietnam. However, surface water resources in coastal areas are facing many challenges such as organic matters and the risk of saltwater intrusion due to the impacts of socioeconomic development and climate change. This article evaluates the impact of salinity on the effectiveness of surface water treatment using ultrafiltration membrane technology for domestic water supply, at laboratory and pilot scale. On a laboratory experimental system, when the input water salinity increased from 0.06% to 0.48%, the treatment efficiency decreased from 88.3% to 86.7% for turbidity and from 66.7% to 62.2% for organic matter. Research results from pilot system showed that when the average salinity increased from 0.025% to 0.125%, the efficiency of organic matter treatment reduced on average from 75.5% to 63.8%, the turbidity treatment efficiency remains unchanged. In addition, when the input water is saline with Bromine concentration at a value of 11.35 ± 1.62 mg/l, the formation of disinfection products containing Bromine such as Bromoform, Bromodichloromethane and Dibromochloromethane occurs quickly and at a higher concentration than the standards, especially when residual chlorine is high (0.8 mg/L). Therefore, it is necessary to well control the saltwater intrusion into river water sources in coastal areas when using this source for domestic water supply.

Keyword: Surface water, salinity, membranes, domestic water.