Analysis And Evaluation Of Potable Water Quality Safety In Xi'an

After China commenced her reform and started to be open to the outside world, the country has achieved high-speed economic development continuously, but at the same time plenty of industrial wastewater and domestic water has drained to the aqueous system without treatment, which polluted the water sources, especially the surface water sources. A flood of pollutant, particularly organic pollutants are still on the way to the aqueous system which of course cause the polluted condition bad to worse.At the same time, as the research on relationship between potable water and life health carried on and living standard advancing, people demand more and more about the water quality. So the number of the indices of water quality is getting bigger and the limit value of every entry is becoming more and more strict.Traditional drinking water treating process still prevails in China. So it becomes necessary that the potable water quality be detected and safety risk be evaluated to guarantee the human health.According to the drinking water quantity and the map of network of Qujiang water supply company in Xi'an City, three typical monitoring point were chosen, namely Qujian water company outflow, middle part of the network, and the end point of the network. And 8 monitoring indices were adopted as typical indices of drinking water quality evaluation in Xi'an, namely PH value, turbidity, Aluminum, TOC, UV254, residual Chlorine, total bacterial count, Escherichia coli. And the correlativity of TOC, UV254, and turbidity were analyzed, as well as that of residual Chlorine and biological indices. Making use of cumulative probability analysis methods, the indemnity rate of the Aluminum, TOC, and biological indices of the three monitoring point were calculated, respectively. In addition, adopting the four step rule annunciated by American Academy of Science (AAS), the residual aluminum ions of the tap water in Xi'an City were studied for the Chemical health and harm risk assessment.The experimental result shows that the pH value and the turbidity both come to the potable water quality standards executed by now in China.The indemnity rate of the biological indicesperforms fairly well. The rate of total bacterial count is 100%, and the residual chlorine more than 90%.According to the standard abroad, the safety indemnity rate of the organic matter index TOC comes to only 75.29%.The study also shows that the aluminum ion concentration exceeds standard, and its safety indemnity rate is only 60%.But through risk assessment, the value is still acceptable, but greater attention must be paid.