Study On Emergency Treatment Of Potable Water Suddenly Polluted By Organochlorine Pesticides

Accidents or disasters might make potable water polluted by organochlorine pesticides. And organochlorine pesticides belong to POPs, which is a kind of substance that is difficult to be degradated, easily bioaccumulated and poisonous to creatures. So, sudden pollution of raw water by organochlorine pesticides will affect drinking water safety of conventional water treatment processes. In order to guarantee the reliability of the water supply, it is necessary to study safety guarantee technology and emergency disposal methods to remove organochlorine pesticides from drinking water.For conventional water treatment processes, its removal effect and factors to lindane and acetophenate respectively are studied. The main influence factors are pH, turbidity, humic acid and Ca(â…¡). The results showed that the removal effect of lindane and acetophenate just by coagulation are low and the residual concentrations are higher than the concentration limits of national water quality criteria. The removal effect of acetophenate rises up with increase of pH value. The removing rate of lindane substantially unchanges with increase of pH value. The effect of lindane and acetophenate removal changes with pH value rising. The direction of their change is first up, then down, finally up. Besides, the best effect of them both is at 45NTU and the best removal rates separately are 12.4% and 17.1%. The removal effect of acetophenate rises up with increase of humate concentration. The removal rate of acetophenate goes down with increase of Ca(â…¡) concentration. Because lindane and acetophenate can not be removed effectively by conventional coagulation-sedimentation processes, oxychloride, permanganate, ozonation and powdered activated carbon adsorption are used as strengthening measures in pretreatment to remove lindane and acetophenate. The removal effect and factors of the above four strengthening measures are studied. The results showed that pretreatment of oxychloride, permanganate and powdered activated carbon adsorption respectively to lindane and acetophenate can not reach the concentration limits of national water quality criteria.The removal effect of ozonation to lindane and acetophenate are very remarkable, by which the residual concentrations of lindane and acetophenate in drinking water are lower than the concentration limits of national water quality criteria.Besides the removal of lindane and acetophenate increases with the increase of ozone concentration and pretreatment time. Combined use of permanganate and powdered activated carbon can observably improve the removal rate of lindane and acetophenate in drinking water. In the experiment the removal effect and factors of combining permanganate and powdered activated carbon process to different overweight multiple raw water polluted by organochlorine pesticides are studied. The main influence factors are pH, turbidity, humic acid and Ca(â…¡). The results showed that the residual concentrations of lindane and acetophenate in drinking water by permanganate and powdered activated carbon process are lower than the concentration limits of national water quality criteria. pH, turbidityand humic acid have an unconspicuous effect on the removal of lindane and acetophenate. However, Ca(â…¡) is a very important factor to combining process. With increase of Ca(â…¡) concentration the removal of lindane and acetophenate goes down. While Ca(â…¡) concentration is 3mg/L, the removal rates of them respectively descrease by 10% and 16%. In short, permanganate and powdered activated carbon process can effectively remove organochlorine pesticides from potable water, and it is easy to join in the existing water treatment process.