| The municipal solid waste have a large increase due to rapid development and urbanization,landfill leachate is produced in large quantities due to local sanitary landfills.Landfill leachate is the problem of wastewater treatment in China,it is complex water quality components,difficult to degrade material,biodegradable and contains a large number of toxic and hazardous substances.It is difficult to achieve satisfactory results using a single technology or a traditional biological method,so at present,a combination of a variety of processing methods are being discussed and applied.In this study,TiO2 and bentonite are cheap and non-polluting environment-friendly materials,they can achieve complementary optimization effect,while bentonite can be used as TiO2 carrier,and TiO2 is also bentonite pillars.The photocatalytic oxidation is an excellent high-level oxidation technology,which has unlimited exploration and development in the landfill leachate treatment.At the same time,because coagulation technology is the most traditional water treatment technology,this paper studies the feasibility of TiO2-organobentonite combined with coagulation technology,and discusses its treatment effect in the treatment of aged landfill leachate.In this study,organobentonite was prepared by using hexadecyltrimet-hylammonium chloride(CTAC)as the organic modifier of bentonite.TiO2-organobentonite was prepared by sol-gel method using butyl phthalate and organobentonite as the main materials.The optimum conditions for the removal of COD and NH3-N in aged landfill leachate were as follows:CTAC addition amount 2.0 g/L and calcination temperature 500 ℃.The results of ESEM,EDS,FTIR,XRD and BET were used to characterize the powder samples,which indicated that TiO2 was uniformly supported on the surface of organobentonite.When the aged landfill leachate was photocatalytic treated by TiO2-CTAC2.0,the COD removal rate increased with the decrease of pH value,and the removal rate of NH3-N increased with the increase of pH value.COD and NH3-N removal rates after rising first decrease slightly with the increase of the dosage of TiO2-CTAC2.0.COD and NH3-N maximum removal rates were 67%and 60%,respectively.Synthesizes the removal rate of COD and NH3-N,the optimum experimental conditions were as follows:the dosage of TiO2-CTAC2.0 was 4.5 g/L and the pH value was 6.5.The removal rate of COD and NH3-N was 51%and 45%.The removal rate is basically unchanged when TiO2-CTAC2.0 recycled 3 times.The combination of TiO2-CTAC2.0 and PAC coagulation technology was used.It was found that the PAC coagulation reaction was better after photocatalytic reaction compared with the simultaneous and coagulation experiment before the photocatalytic experiment.The COD and NH3-N removal rates were 85%and 42%,respectively,when the dosage of TiO2-CTAC2.0 was 4.5 g/L,pH 5,PAC dosage 800 mg/L and reaction time 180 min.The relationship between the operating variables and COD and NH3-N removal rates was analyzed by response surface methodology,the manipulated variables were the dosage of TiO2-CTAC2.0,reaction time,pH value and PAC dosage.Considering the removal efficiency of COD and NH3-N,the optimum experimental conditions were as follows:TiO2-CTAC2.0 dosage 5.09 g/L,pH value 5.53,reaction time 180 min and PAC dosage 1062 mg/L,the COD and NH3-N removal rates were 84%and 44%,respectively. |
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