Abstract:
Objective To study the quality trend of water from water plants in Songjiang District, Shanghai by analyzing the monitoring data, and to provide scientific basis for developing water supply planning and supervision.
Methods The selected water plants' monitoring data of raw water and finished water from 2006 to 2012 were collected to analyze the qualified rate of finished water and the distribution of unqualified indices. The effects of raw water and water preparation process on the quality of finished water were also analyzed.
Results From 2006 to 2012, 10 water plants(town level)with conventional water treatment process were closed, while the number of water plants with advanced water treatment technology increased by 2(district level). An uptrend was shown in the qualified rates of the finished water samples(χ2=31.82, P<0.01). Organic pollutants was the main pollution in the finished water, and ammonia nitrogen(NH3-N)accounted for 44.61% in total unqualified items and chemical oxygen demand(COD)accounted for 31.99%. Applying advanced treatment, the concentrations of NH3-N and COD of the same raw water were significantly lower than those using conventional treatment technology(tNH3-N=4.53, PNH3-N<0.01; tCOD=8.32, PCOD<0.01).
Conclusion Raw water quality and preparation process are key factors of the quality of finished water. Expanding raw water supply scope of Xietang River and promoting application of advanced treatment process are strongly advocated to improve the finished water quality in Songjiang District.
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