Advanced Treatment Of Landfill Leachate By Combined Process Of PFS Coagulation-Catalytic Ozonation-Biological Aerated Filter

Landfill leachate has the features of complicated organic compositon,biological toxity and poor biodegradability.It is very difficult to treat for disposing.The common biological treatments for landfill leachate can't meet the new discharge standard.Nowadays membrane technology was usually adopted as advanced treatment,which could make the effluent of landfill leachate reach the discharge standard,but there were some problems such as high running expense and the concentrated solution was difficult to treat.Therefore,developing other advanced treatments for landfill leachate which have engineering value becomes a research focus.In this study,a combined process of Polymeric Ferric Sulfate(PFS)Coagulation-Catalytic O zonation-Biological Aerated Filter(BAF)was developed for the advanced treatment of MBR effluent of landfill leachate,which made the effluent successfully meet the discharge limit of landfill leachate pollution control standard in China(GB16889-2008).The feasibility of the combined process was proved by the laboratory small experiment,which put the base to get optimal process parameters.The removal efficiency of PFS was superior to PAC and FC,the best removal rate was obtained under the condition of PFS dosage of 1400mg/L,initial p H of 6.0 and PAM dosage of 4mg/L.The addition of ceramic containing manganese oxide as catalytic significantly improved ozonation efficiency,the degradation effect on basic condition was better than that on acidic condition,the optimal ozone dosage was 150mg/L and the suitable initial p H was 7-8.The effluent CODCr of BAF could below 100mg/L when the residence time was 6h.UV-vis absorbance and three-dimensional excitation emission matrix fluorescence spectroscopy(EEM)were used to analyze effluent from each unit,which initially revealed the removal mechanism of pollutans of the combined process.The result showed leachate of MBR effluent mainly contained humus with conjugated and chromophoric groups,and the complicated degree of organic compounds was simplified by the combined process.Coagulation was adopted for pretreatment to reduce quantity of pollutants.and the catalytic ozonation effectively eliminated the humic substance and improved the biodegrability.The main purpose of BAF is the further degradation of biodegradable pollutant,and microorganism metabolite was produced simultaneously.Based on the pilot-scale experiment,this paper studies the applied value of the combined process.The result showed a good removal performance with the CODCr removal efficiency of 86.0%.The final effluent CODCr was below 100mg/L,which successfully met the discharge limit.The optimal operation parameters were the followings 1.4kg/m~3 of PFS,0.26kg/m~3 of NaOH,0.1kg/m~3 of H2SO4,4g/m~3 of PAM,150-200g/m~3 of ozone,and HRT of 4.5 h for BAF,respectively.Cost analysis suggested that the operational cost of the combined process was about 6.68 yuan/m3,which is more economical than the current commonly-used technology.