Research And Selectness Of Disinfection Technology For Waterworks In Small Towns

The small towns take a significant function in the sustainable development, which can affect the urbanization in China. However, waters are polluted severely and the quality sdandards of drinking water sdandard are improved, which challenge the traditional chlorination disinfection. Therefore, the technical analysis and economic comparison of the disinfection technology in small towns are necessary. Based on the financial and natural conditions and the scale of the waterwork in small towns, chlorine disinfection, chlorine dioxide disinfection, UV disinfection and chloramines disinfection are chosen as the suitbale technology to waterworks.When the scales of waterworks are defined as 0.5×10~4m~3/d, 1.0×10~4m~3/d, 2.0×10~4m~3/d and 3.0×10~4m~3/d, it is designed to the four processes severally. Through economic calculation, the mathematical models of the investment and operational cost with the treatment scale are put forward. And the best economic project is confirmed in different scales by NPV (net present value) analysis: UV disinfection is uneconomic and chloramines disinfection is inferior to chlorine disinfection when the scale is between 0.5×10~4m~3/d and 3.0×10~4m~3/d, chlorine dioxide disinfection is the best economic project when the scale is under 1.0×10~4m~3/d, chlorine dioxide disinfection is more economic than chloramines disinfection under 2.0×10~4m~3/d.Four technical processes are evaluated comprehensively with analytic hierarchy process. The results are as follows: When scale is under 2.0×10~4m~3/d, the best process is chlorine dioxide disinfection, the second is chlorine disinfection, the third is chloramines disinfection, the last is UV disinfection. When the scale is 3.0×10~4m~3/d, the best process is chlorine disinfection, the second is chlorine dioxide disinfection, the third is chloramines disinfection, the last is UV disinfection. When the scale is under 1.0×10~4m~3/d, chlorine dioxide disinfection takes on visible advantage. The advantage is increased sharply as the scale adds, and UV disinfection has not demonstrated its superiority in miniature.The mathematical models, the results of technical analysis and economic comparison are helpful for the construction of the waterworks in small towns in China.