Study On Modified Attapulgite Treating Low Temperature Low Turbidity Water

During the normal process of water treatment,treating low temperature and low turbidity water often encounters many difficulties. Because of the low temperature and the low turbidity,it is difficult to reach the effluent standard by using the conventional water treatment. In this case,the author focus on studying the effect of the mixture of the modified attapulgite clay and interaction agent to the treament of the water in the process of coagulation. for addressing the difficulties of treating low temperature and low turbidity water,ensuring the reasonable operating costs and reaching the requirement of water quality standardAttapulgite is a kind of water rich magnesium aluminum silicate clay,which has the excellent physical chemical properties. The different attapulgite activity modification experiment have been proceeded to investigate the influence of attapulgite to the congulation process. Experimental study on the low temperature and low turbidity water by enhanced coagulation activation by the different.During the thermal activation modification experiment, the author has researched the effect of attapulgite to the coagulation process by comparing the result under different modification time and temperature of appapulgite. It turns out that the most satisfied coagulation result can be obtained under the 400?modification temperature and 3h modification time. During the acid activation modification experiment,the author has researched the effect of attapulgite to the coagulation process by comparing the result under different attapuligite,which have been treated by different kind and concertration acid. It turns out that the most satisfied coagulation result can be obtained with the helping of appapulgite,which has been acid by 3 mol/L HCl. According to the optimum preparation conditions of heat, acid test, thermal activation preparation of acid modified attapulgite was produced.The heat-acid combined with polyaluminium chloride coagulation activation of attapulgite and commonly used(PAC) and polyferric sulfate(PFS) respectively for coagulation tests. The best ratio of coagulant and the modified attapulgite clay was dertamined by investigation of coagulant dosage, modified attapulgite dosage, dosing sequence of variables. The results show that adding coagulant in the fast mixing speed(280 rad/min), adding modified attapulgite in the intermediate mixing speed(150 rad/min) in 1min, treatment effect is the best. Besides, the best dosage of polyaluminium chlorides is 9.65 mg/L, the best dosage of modified attapulgite is 0.57 mg/L,the best dosage of polymeric ferric sulfate is 45.94 mg/L,the best dosage of modified attapulgite is 2.16 mg/L.Comparing with using the coagulant polyaluminum chloride and polymeric ferric sulfate respectively, the removal rate of turbidity and COD removal rate increased by 15.59%, 8.79%,15.24% and 7.69% by using the mixture of these two substances.Consideration of the market price of the polyferric sulfate and the effect of the color of the raw water, It should adopt modified attapulgite collaborative polyaluminium chloride to treating low temperature low turbidity water. Under the best conditions for investment ratio, turbidity and COD re moval rates were 89.92% and 37.16%.