The Study On Treatment Of Landfill Leachate By Activated Diatomite Composite Enhanced Coagulation

This research subject is mainly aiming at probing into some basic problems existing in the application of this technology, in particular,problems about the blends of activated diatomite and coagulants,the influencing factors for the efficiency in removing pollutants of the technology,and the mechanism of the technology in treating landfill leachate. In this research subject,influence factors of activated diatomite as coagulant for the advanced treatment of landfill leachate was studied.The experiment compares two kinds of flocculants,which are polyaluminium chloride(PAC) and polyferric sulfate(PFS).Through the experiment,polyaluminium chloride(PAC) is selected to blended with activated diatomite.The influence factors of activated diatomite blended with PAC as coagulant for the advanced treatment of landfill leachate was studied. On the basis of laboratory's condition,this research subject,the medium-scale experiment was also conducted.The scale of medium-scale experiment is 100L/h.The pilot-plant is mechanical mixing flocculation-sloping tube settling tank.The optimum condition of activated diatomite as coagulant for the advanced treatment of landfill leachate is as following:a pH value of 6,a water temperature of 15~25℃,a hydrodynamics condition of 360r/min(60s)+ 90r/min (5min),and 30min sediment time.Experimental results showed that,under the optimum condition,the removal efficiency of COD and UV500 could reach to 38.36% and 75.00% respectively.Enhanced coagulation two times under the optimum condition,the total removal efficiency of COD and UV500 could reach to 49.34% and 93.18% respectively..The optimum ratio of PAC to the activated diatomite is 1∶1.The optimum condition for flocculation is as following:a pH value of 6~7,a water temperature of 15~25℃,a hydrodynamics condition of 200r/min(60s)+90r/min(15min),and 30min sediment time.The best composite coagulant dosing method is activated diatomite feeded in the the beginning and PAC feeded in the 30s.Under the optimum condition,the removal efficiency of COD and UV500 could reach to 51.91% and 86.40% respectively.Enhanced coagulation two times under the optimum condition,the total removal efficiency of COD and UV500 could reach to 67.93% and 95.20% respectively. The results of the medium-scale experiment is shown below.When adding a separate PAC,the removal efficiency of COD and UV500 could reach to 51.47%~56.66% and 84.66%~87.12% respectively. When adding a separate activated diatomite,the removal efficiency of COD and UV500 could reach to 39.98%~51.88% and 69.80%~74.50% respectively.When the activated diatomite mixed with the PAC adding, the removal efficiency of COD and UV500 could reach to 50.89%~57.10% and 85.96%~88.30% respectively.When the activated diatomite with the PAC adding respectively,the removal efficiency of COD and UV500 could reach to 50.66%~55.76% and 86.75%~89.16% respectively. When the activated diatomite with the PAC adding respectively and enhanced coagulation two times,the total removal efficiency of COD and UV500 could reach to 63.05%~67.62% and 91.22%~92.40% respectively.UV scanning test results showed that coagulation process on the aromatic organic compounds,especially polycyclic aromatic hydrocarbons removal of a better role.When the activated diatomite mixture with PAC using in the coagulation process, it have not only both coagulation but also adsorption.