The Research On Coagulation-Adsorption Processing Secondary Effluent Of Municipal Wastewater Treatment Plants

The water environment has been extremely endangered by the increacing of the amount of sewage discharge.At present,there is no effective wastewater treatment to remove all pollutant in the wastewater treatment plant of our country.In order to make the sewage discharge satisfied the drainage standard,secondary effluent of municipal wastewater treatment plant must be treated deeply and made the discharge goal realized.In this paper,The treatment process of secondary effluent wastewater from municipal wastewater treatment plant have been researched.With this research,Making the effluent quality complying to the Discharge standard of pollutants for municipal wastewater treatment plant(GB 18918-2002) is the aim.The results of coagulation tests are as below:(1) TP,CODcr in secondary effluent can be removed effectivly by coagulant,but the result for NH3-N is not good.(2) The most compatible coagulate flocculating agent to treat secondary effluent among the choiced coagulants is PAC.(3) The optimum conditions for PAC which is used as coagulant are as below:m=20m/L,pH=7,r=150r/min.The results of adsorption experiments are as below:(1) CODcr,NH3-N can be removed by zeolite effectively,but TP can not be removed as good as it treated by coagulant. the optimum conditions for zeolite are:m=4mg/L,pH=7.5, t=45min.(2) CODcr,NH3-N,TP can be removed better by modified zeolite。(3) One of modifying conditions for zeolite is sulfuric acid concentration 4mol/L,under this congdition,CODcr、NH3-N in secondary effluent can be removed effectivly.(4) The optimum modifying conditions for zeolite are:m=4mg/L,pH=7,t=30min.The results of process experiments are as below:(1) TP,CODc,NH3-N can not be removed simultaneously by single treatment.(2) TP,CODcr,NH3-N in secondary effluent can be removed effectively by coagulation&adsorption and adsorption&coagulation.(3) Treatment effect of TP,CODcr,NH3-N by coagulation&adsorption test is better than adsorption&coagulationSingle method can not make the effluent quality complying to the Discharge standard of pollutants for municipal wastewater treatment plant(GB 18918-2002) is showed through the results of the experiments. Combining use of coagulation and adsorption is an effective way to treat secondary effluent of municipal wastewater treatment plant and using coagulation before adsorption is suitable.