Relationship Between Environment Temperature, TOC, Turbidity, and HPC on Free Residual Chlorine in Municipal Drinking Water Distribution Networks (WDNs): A Case Study (Abadan, Iran)

Abstract

AbstractWater distribution systems are considered vital arteries of urban communities. The purpose of a water supply distribution system or network is to provide water to consumer with adequate pressure and quality. The quality must be healthy and standards in terms of chemical and biological standards. Chlorine is used as the most common disinfectant in municipal drinking water supply networks due to its high efficiency and economy. The aim of this study was to assess the effect of environmental temperature on residual chlorine, turbidity, TOC and HPC in Abadan, Iran, WDN, during summer and winter seasons. In this cross-sectional study, according to the water supply maps, the 232 samples from different point of WDN were analyzed to measurement of free residual chlorine, total organic carbon (TOC), Turbidity (NTU), and heterotrophic plate count (HPC) (cfu/100 ml), based on the standard methods for examination of water and wastewater (APHA). Samples were collected from effluent of water treatment plant to distribution system according to the Cluster sampling model. Regression analysis was used to investigate the relationship between variables. Results show that temperatures in Abadan typically range from 29 to 46 °C at summer and 12 to 27 °C in winter. Statistical analyzes show that as the ambient temperature increased, the free residual chlorine in the distribution network from the water treatment plant decreased to the end of the distribution network and reached zero at some end points (R2 = 0.97). Also TOC, Turbidity (NTU), and HPC (cfu/100 ml) showed a significant increase with increasing environmental temperature in distribution network (P < 0.05). According to the results of this study, in cities with high seasonal air temperatures, due to changes in the water quality of the distribution network, it is necessary to take re-chlorination, change the coagulation and flocculation process of surface water treatment plants in, and continuous monitoring of WDN in hot seasons.KeywordsEnvironment temperatureFree residual chlorineNOMTurbidity and HPCWater distribution system