Experimental Research On The Effect Of Adding Pac In The Influent Of Filter On The Performance Of Filter

Powdered Activated Carbon (PAC) has been widely applied to the water treatment owing to its advantages on large contact area, quick absorbing speed, perfect effort, abundance source material and lower price. It is a simple and effective way to add PAC into conventional water treatment processes in the technology of using PAC. There are three dosage points to select, raw water suction well, process of coagulation and the influent of filter. Different dosage points have their own advantages and disadvantages. Theoretically speaking, adding PAC in the influent of filter can reduce competition of PAC with coagulant to the max, give full play to adsorption of PAC, and use it more efficiency. The major problems in this technology are PAC penetrating filter material layer and the great shorten of the filter cycle owing to the growth rate of filter head loss is so quickly. The paper consider finding availably way to resolve those questions and make the technology can use widely.Choosing the kind of PAC and the style of filter are suited to the the technology of adding PAC in the filter influent by the water turbidity of filter effluent and the growth rate of filter head loss based on the laboratory scale tests. The study on the static test of PAC adsorption shows the adsorption rate and adsorptive capacity for the organic matter of PAC. The?place of pilot plant test is Chongqing daqiangba water plant and this test focus the results of water treatment and the period stability of the technology about adding PAC in the filter influent. Finally, the technical economical analysis about adding PAC in the filter influent compared with others dosage points was studied.The influent of filter is city tap water,filtering velocity is 10m/h,after adding PAC in the filter influent, the water turbidity of the filter effluent is not ideal. In contrast, the filter was good at interception the PAC of 150~200mesh owing to its characteristic on the diameter is bigger and well-distributed, reduce the dose of PAC and slow down filtering velocity?can decrease quantity of PAC that penetrated filter material layer to a certain extent. Adding coagulant can significantly raise the PAC interception rate of filter. After adding PAC in the down flow filter influent, the growth rate of filter head loss is so fast because of the PAC is automatically intercept by the small filter material particles on filtration bed upside. The growth rate of filter head loss when adding PAC in influent of the up-flow filter and the uniform media filter is?slow and the filter cycle is ideal. The results of the study based on the static test of PAC adsorption are described as the followings: The CODMn removal efficiency of water sample is best as the dosage of PAC is 15mg/L and the UV254 removal efficiency of water sample stabilized as the dosage of PAC is 20mg/L, the removal rate of organic matter increase velocity reduction as continue raise quantity of PAC. The PAC can finish 60~70% of the total adsorption quantity after PAC coming into contact with water about 10 minutes and the PAC exert its full adsorption quantity in one hour.The quantity of coagulant contain in the clarification tank effluent can assist in filter intercepting PAC efficiently and the filter effluent is best as the grain diameter of PAC is 150~200mesh.The continuous operation test results demonstrate the water turbidity of filter effluent can maintain below 0.3NTU stably as adding 10mg/L PAC of 150~200 mesh in the filter effluent. The removal rate for the CODMn, UV254 in the water of clarification tank effluent brought by the technology adding PAC in the effluent of filter is higher about 30% than didn't add and the filter cycle is long.The removal rate for organic matter of water can also increase 10% when adding PAC in raw water suction well and process of coagulation. The result is best as adding PAC in water 30s behind adding coagulant. On the whole, in the technology of adding PAC in the filter influent the dosage is lower and got better results owing to the high utilization rate of PAC. The equipment disposable investment of directly added in conventional water treatment processes technology is not big and its costs for operation is low.