Study On The Controlling Of Harpacticoida Pollution Risk In Drinking Water Treatment Process

In recent years, with increased pollution of water quality, most copepods inzooplankton such as Harpacticoida and Cyclopoida are over-breeding in water sourcesnoticeably. Exceed its environmental capacity, daphnids may enter the water plant withthe raw water to penetrate the water purification process and then into the water supplynetwork, finally result in water pollution. For this, one of a large number ofmicro-aquatic organisms Harpacticoida in a southern city water purification process asthe object of study for this thesis, first carried out the conventional water purificationprocess about the study of Harpacticoida’s removal and removal rule,then carried outthe study of chemical oxidation to control the risk about Harpacticoida. Based on theabove, the oxidant and sand filtration as the core to synergy, and established thetechnology of high efficient control for risk of Harpacticoida in the water purificationprocess, this is technology of interception and inactivation. For water purificationprocess, especially Those works could supply some theoretical guidance and technicalsupport for pollution risk control technology for Harpacticoida in Biological ActivatedCarbon advanced treatment technology. The main conclusions are as follows:(1) The Coagulation and sedimentation had interception effect on the removal ofHarpacticoida, under various experimental conditions, removal rate in more than89%. But the operation conditions of Coagulation and sedimentation significantlyaffect the removal rate. In present test, the highest interception efficiency of96%was obtained with program as300rpm1min、150rpm5min、75rpm5min, the optimal coagulant dosing for Harpacticoida interception was12~15mg/L, becauseof extending the settling time will lead to reducing the interception effect,so thesettling time of0.5h is the best.(2) Remarkable interception effect of sand filter to Harpacticoida was observed inpresent test, but the intercept effect is significantly affected by filtration rate andfiltration cycle. The test results show that when the sand filter filtration rate morethan15m/h, Harpacticoida penetration will reach up to61.26%; Appropriate toshorten the filtration cycle will help the sand filter to remove the Harpacticoida, tocontrol the velocity for9m/h and the filter cycle for1d, at which93.43%Harpacticoida removal efficiency was obtained.(3) The chemical oxidant towards Harpacticoida ’s inactivation is mainly affected bythe oxidant’s oxidation properties. Chlorine dioxide towards Harpacticoida’sinactivation effect is the best, and the influence of water quality conditions forinactivation is weak, dosage of0.4mg/L, contact0.5h can achieve100%inactivation.; Under the experimental conditions, liquid chlorine dosage of3mg/L, exposure to2h, at which100%inactivation of fierce Daphnia will be reached,inactivation is significantly impacted by the pH value of water and organic mattercontent; Potassium permanganate inactivation is the worst, dosage of20mg/L,contact2h, the inactivation rate just only10%.(4) Interception and inactivation technology has significant effect on Harpacticoidarisk controlling, mainly through the synergy of sand filter to intercept andoxidative inactivation. Interception of sand filters can effectively extend thecontact time for oxidative inactivation, the oxidation of pesticides have toxiceffects on Harpacticoida can reinforce the intercept effect of sand cushion. Whenchlorine dioxide dosage reach0.2mg/L, it can be one hundred percentinterception of Harpacticoida, it is also can remove completely by backwashing.