Study On Removing Algae By Micro-Flocculation Fiber Filtration In Treatment Of Micro-Pulluted Raw Water

In April,2008,the blue algae happened again in Tai Lake.The water there was damaged,which influenced the local living and process water.How to deal with the high algae water now is one of the major problem about water pollution.Currently, our country usually takes coagulate,preoxidation,floatation,filter,etc.Nevertheless, those processes have their limits as well as the algae removal.For example,the main problem of traditional coagulate process for algae removal is that the large quantity of coagulant and mud.The direct filter is one the common way to remove algae but high algae is easy to costing filter stoppage and filter bed penetrate.The experiment of algae removal was conducted by using self-developed high stretch yarn terylene fiber-ball.This paper studied the filtering characteristics and effect of correlative factors on filtering performance.The filtering velocity,sewage removal capacity,specific surface area and other characters of this new filter are much better than traditional granular and fiber filter.The application of filter is not only an advantage algae removal process but also a new filter material.This experiment is aimed at Shanghai Songjiang University Lake(algae amount 8×10~6/L) to study micro-flocculation fiber ball filtration.The whole experiment includes two parts.One is the selection of flocculent and the study about its relevant influence factors.The other is the result of micro-flocculation fiber ball filtrating algae and its relevant influence factors.The main conclusions are the followings:(1) Increasing properly the flocculent dosage could enhance the algae removal of flocculent as well as turbidity.(2) When the algae total amount is about 6.8×10~6～8×10~6/L,pH is 7 and turbidity is about 8～11,the TN,TP and algae-a removal of three flocculent is:PAC＞aluminum chloride＞ferric sulfate(3) For Songjiang University Lake,aluminum flocculent is better than ferric one and polymer flocculent is better than inorganic one.(4) The micro-flocculation fiber ball filtration experiment indicates that high stretch yarn terylene fiber-ball has good algae removal effect.The removal rate of direct filtration is up to 70%.As to the high algae water(8×10~6/L), when the PAC dosage is 15mg/L,velocity of filtration is 15m/h,the algae amount of effluent keeps under 10~6个/L,the removal rate is over 90%. Moreover the algae amount of effluent keeps under 10~6/L and head loss is less then 160cm.(5) The experiment result indicates that high stretch yarn terylene fiber-ball has the advantage of little dosage,algae removal good,effluent sufficient and steady,operation cycle long,etc.So that the filter ball is a effective filter and having good application.