Study On Wastewater Treatment Performance And Membrane Fouling Of Novel Ultrafiltration Membranes

Membrane process is a novel wastewater treatment technology. This technology has rapid development and a wide concern because of water resource deficiency and water quality deterioration. Membrane process has been used as a key technology for water reclamation and reuse of water resource. In this dissertation, the membranes were used to treat municipal wastewater, and the effluent quality, membrane fouling and cleaning properties were studied. As a result, the following conclusions were drawn:(1) The membranes were used to treat the effluent from sedimentary tank of municipal wastewater treatment plant. The wastewater treatment performance, fouling characteristics and regeneration characteristics of PVDF/PMMA-β-CD, PES-β-CD composite plat ultrafiltration membranes and PES plat commercial membrane were investigated in comparable conditions. The results showed that the effluent can meet the demands of water reclamation. The flux decreased ratios of PES commercial membrane and PES membrane were high during the initial period and tended to stably during the later period. Took the 1.5h for the boundary, the filtration period was divided into two periods. Period ? was fit to the standard blocking filtration model and periodΠwas fit to cake filtration model. The results obtained by cleaning methods of PES commercial membrane and PES membrane showed that backwash has little effect on membrane permeability recovery, and H2O2 soaking is effective to recover membrane permeability. Compared with PES commercial membrane and PES membrane, the flux of PVDF membrane was in a stable state, the operating time of PVDF membrane was six times as much as that of PES membranes and PVDF membrane didn't need membrane cleaning. The results showed that the hydrophilicity of the modified PVDF membrane was excellent and membrane fouling was slightly.(2) Two different types of composite fivebore hollow fiber membrane modules which are module A (PVDF/PMMA/TPU blends) and module B (PVDF/PMMA/PVC blends) in presence of the same biomass concentration were applied to verify the effluent quality, fouling characteristics for domestic wastewater treatment. All the results of the experiments were complied with standard of the effluent discharge standards to urban miscellaneous water consumption (Reuse of recycling water for urban-Water quality standard for urban miscellaneous water consumption) (GB/T18920-2002). The system produced effluents equivalent to those of an oxidized, coagulated, clarified, filtered, and disinfection wastewater and could reduce following tertiary treatment process, endanger of chlorine precursor was completely eliminated. The method of mitigating membrane fouling was studied. The result showed that the more severe fouling happened during the constant condition. The optimum operation condition of intermittent filtration condition of suction time/suspended time ratio was 10min/2min, membrane fouling increased as suction time/suspended time ratio increased, membrane fouling rate reached lowest during suction-backwashing condition. The PVDF/PMMA/TPU blends did a little better than the PVDF/PMMA/PVC blends in terms of removal efficiencies. The results showed that PVDF/PMMA/TPU blends and PVDF/PMMA/PVC blends posses excellent characteristics.The result of fouling resistances propensity showed that the reversible fouling resistances, which was produced by concentration polarization and can be removed by physical cleaning, was the main membrane resistance, then was the intrinsic membrane resistance, and the resistance caused by solute adsorption into the membrane pores and wall was the least. The anti-fouling characteristics of membranes were excellent. By measuring the flux of membrane and cleaning membrane module of different methods, it was founded that wash out by water and soaking in NaClO solution was effective in control blend membrane module pollution. The latter study also verify the conclusion and the membrane flux recoveries were over than 90%. Compared with the module B, the module A had better anti-fouling characteristics, the operating time of module A was twice as much as that of module B.In conclusion, the modified PVDF blend membranes would be well applied in the future. The research studied on wastewater treatment performance and membrane fouling of novel ultrafiltration membranes would provide a reference basis for the application of novel anti-fouling ultrafiltration membranes on wastewater treatment.