Study On The Application Of Wastewater Treatment In Waste Plastic Granulation Production

With the release and implementation of the technical code for pollution control of waste plastic recycling and recycling(Trial)and the plastic restriction order,the pollution problems in the plastic recycling industry need to be solved.A waste plastic pelletizing enterprise in Jiangxi Province will produce a certain amount of high concentration organic wastewater in production.A set of wastewater treatment facilities should be built in the plant.According to the characteristics of high concentration of COD,ammonia nitrogen and petroleum in the wastewater of the plant,this project seeks for an effective and more economical wastewater treatment scheme for waste plastic granulation production,and after commissioning,the discharge is up to the standard.On the basis of literature review and experimental study of wastewater,the combined scheme of "coagulation air flotation+Fenton oxidation+coagulation precipitation+UASB+biological contact oxidation+sodium hypochlorite oxidation"is finally adopted for comprehensive treatment.After experimental research and debugging operation data,the following conclusions are formed:(1)According to the results of single factor experiment,it shows that the effect of coagulation and air floatation on oil removal is better.The best reaction conditions are PAC dosage of 300mg/L,PAM dosage of 15mg/L,pH value of 8,and dissolved gas pressure of 0.3MPa.The removal rates of COD and petroleum are 41.1%and 85.6%respectively.(2)According to the results of single factor and orthogonal test,it is shown that Fenton reaction can effectively remove COD and petroleum pollutants from wastewater,and the optimal reaction conditions are as follows:the dosage of ferrous sulfate heptahydrate is 5g/L,the dosage of 30%hydrogen peroxide is 5ml/L,the reaction pH value is 4,the reaction time is 150min,and the removal rates of COD and petroleum are 51.2%and 84.2%,respectively.(3)According to the experiment of sodium hypochlorite oxidation on the physicochemical wastewater,the best reaction conditions of sodium hypochlorite oxidation of ammonia nitrogen are obtained by single factor and orthogonal experiment:the effective chlorine to ammonia nitrogen molar ratio is 2.5:1,the reaction pH value is 8,the reaction time is 40 minutes,the ammonia nitrogen concentration of the effluent is 18.5 mg/L,and the ammonia nitrogen removal rate is 85.1%.(4)After the UASB reactor in stable operation reaches the design standard,the removal rate of COD is stable between 75%and 85%.(5)The effluent from the anaerobic tank enters into the biological contact oxidation tank.After the start-up and commissioning,the removal rate of COD and ammonia nitrogen can be maintained above 60%and 57%respectively.(6)After the system is started and operated successfully and stably,the COD concentration of influent water is about 13697mg/L,ammonia nitrogen concentration is 310.8mg/L,petroleum is 118.8mg/L.With this process,the COD concentration of effluent water is reduced to 295mg/L,the average removal rate is 97.8%,ammonia nitrogen concentration is reduced to 41.7,the average removal rate is 86.5%;the concentration of petroleum is reduced to 0.6,the average removal rate is 99.5%.All of them can meet the receiving standard of sewage plant in the park.(7)After the sewage treatment system operates stably,the treatment cost is 23.4 yuan/m~3,excluding the depreciation cost of labor and equipment,which has certain economic significance and provides a reference for the treatment of wastewater in the same type of industry.