| The development of efficient technologies on advanced wastewater treatment is significant for improving the water quality of the effluent discharged by present wastewater treatment plant,meeting the stricter and stricter pollutant discharge standards and solving water pollution problem.Membrane separation technology has been widely applied in advanced wastewater treatment because it could effectively remove suspended solids and pathogens.However,the major issues such as low efficiency for the separation of small molecular organic pollutants and membrane fouling retard the development of membrane separation in real application.In this dissertation,membrane separation technology was coupled with catalytic ozonation technology by fabricating a novel ceramic membrane with the function of catalytic ozonation.The performance of the ceramic membrane on wastewater treatment is enhanced,and the membrane fouling is mitigated attributing to the degradation of organic pollutants by oxygen radical species generated from catalytic ozonation.This dissertation contains the following works:(1)Mesoporous ?-MnO2 with high activity on catalytic ozonation was prepared.To improve the surface area of the catalyst,a mesoporous manganese oxide(?-MnO2)with ordered nanorods was prepared by template method with SBA-15 as sacrificial template and Mn(NO3)2 as precursor.The surface area(142 m2/g)is 10 times as much as that of the control catalyst prepared by template method without the use of SBA-15.Hydroxyl radical was identified to be the main reactive oxygen species in the catalytic ozonation of oxalic acid by the analysis of electron paramagnetic resonance,and the yielded hydroxyl radical was about 2 times as high as that of the control catalyst.The pseudo first order rate constant of the degradation of oxalic acid was 0.018 min-1,3 times as much as that of the control catalyst.The results suggested that the prepared ?-MnO2 was effective for the catalytic ozonation.(2)The preparation method of ceramic membrane with the capability of catalytic ozonation and the performance of the ceramic membrane on advanced treatement of secondary effluent were studied.Manganese oxide was uniformly coated on the surface of the ceramic membrane by sol-gel method.The pore size of the prepared membrane is 50 nm,the porosity is 33%,and the pure water flux is 270 L/m2-h-bar.The wastewater with COD of 100?112 mg/L was treated by the prepared membrane at ozone dose of 1 mg/L,and the results showed that the effluent COD was less than 50 mg/L,and the flux was 120 L/m2·h-bar.Compared with the ceramic membrane without the catalyst coated,the COD removal was increased by 29%,meanwhile the flux was increased by 11%.The results demonstrated that the catalytic ozonation could improve COD removal efficiency and enhance the anti-fouling capacity of the ceramic membrane.(3)An apparatus,which utilized the prepared ceramic membrane as the core module,was designed and applied in the advanced treatment of the wastewater from pigment production and municipal wastewater in pilot scale.The COD,chroma,UV254,E.coli and suspended solids of the wastewater from pigment production was 80?120 mg/L,dilution times of 80?100,1.4?1.8 cm-1,>2.4×106 MPN/L and 15?25 mg/L,respectively.After treatment,the COD decreased to less than 50 mg/L,the chroma decreased to less than dilution times of 30,the UV254 decreased to less than 0.8 cm-1,the E.coli and suspended solids were effectively removed,and the genotoxicity was effectively eliminated.The COD,chroma,E.coliand suspended solids of the municipal wastewater was 25?45 mg/L,dilution times of 32,>2.4 ×1 06 MPN/L and 5?21 mg/L,respectively,and after treatment,the COD decreased to less than 20 mg/L,the chroma,E.coli and suspended solids were hardly detected.The results demonstrated that the technology combining membrane separation with catalytic ozonation could effectively improve the water quality of the wastewater.In summary,the combination of membrane separation with catalytic ozonation could effectively improve pollutant removal and mitigate membrane fouling.This work provides a reference for the application of the ceramic membrane with the function of catalytic ozonation,and offers a new approach for the development of new functional separation membranes. |
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