| From the end of June to the beginning of July 2016,heavy rain for many consecutive days have caused the flooding.It has caused the turbidity of the source water of the only running water purification plant in Xinxian County of Henan Province to rise sharply.And the turbidity of the effluent after the treatment of the existing direct pressure filtration process remained high.The author participated in the research and project implementation of the emergency treatment scheme of urban water supply in Xinxian County for 2 months.Based on the present water treatment facilities of the water plant,this paper adopts three ways to carry out step-by-step test and research.First of all,carry out field test of coagulation process in Xinxian Water purification plant,change the position of the dosing point and determine the best coagulant and the optimal dosage of coagulant at the new point.Then,change the filter media and monitoring the filtration period of the filtered water quality,the filtration effect of the original pressure filter can be improved and the filtration speed of the pressure filter can be controlled.Finally,add coagulant and coagulant to water source to improve water quality and purify surface water.Build siphon pipe to remove upper layer clean water from reservoir to water purification plant,and to reduce turbidity of incoming water.The results indicate that:(1)By changing the dosing point,the coagulation reaction time in the filter tube is increased from 2.17 minutes to 16.30 minutes,and the turbidity removal rate increases from 18.7% to 35.4%.(2)Through the coagulation beaker test,the best coagulant was PAC.The optimum dosage of PACwas 40 ppm when the turbidity of influent was 60 NTU,and the turbidity removal rate increased from 35.4% to 41.7%.(3)The turbidity removal rate was increased from 41.7% to 54.8% by replacing the original single-layer quartz sand homogeneous filter material as double-layer filter material.(4)Through the experiment of filter speed control in pressure tank,when the filtration rate is reduced to less than 10m/h,the turbidity of pre-filtration water can be lower than that of 3NTU when the turbidity of pre-filter water is up to 70 NTU.(5)The pressure filter which can not operate normally is overhauled,in order to maximize the filtration area,reduce the filtration rate of pressure tank,and increase the turbidity removal rate from 54.8% to 65.6%.(6)By measuring the turbidity of the effluent by continuous sampling,the reasonable backwashing period is determined;twice a day,the turbidity of the effluent is stabilized at the lowest possible state.(7)By adding coagulant and coagulant to water source,the turbidity of surface water can be reduced to less than 5NTU.(8)Syphoning surface water,greatly reduces the turbidity of raw water in water purification plant,and ensures that the turbidity of filtered water is lower than that of 3NTU.Through the above research,under the condition that the treatment process of water purification plant can not be changed for a short time,the effluent quality is greatly improved.In the long run,if we want to solve the problem of water supply quality in Xinxian County under extreme conditions,this paper suggests that the reconstruction and extension project of Xinxian Water purification Plant should be carried out from the point of view of the process itself and the root cause of the project should be solved.By analyzing the data of water supply volume from July 2015 to June 2016,this paper discusses the changing rule of water use in Xinxian County.When the high level reservoir water is filtered by pressure in Xinxian Water purification Plant,the water supply is directly supplied to municipal pipe network after disinfection process.The diurnal variation coefficient is 1.450 and the time variation coefficient is 1.462. |
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