Integrated Modified Membrane Bioreactor for Municipal Wastewater Treatment

Strongly hydrophobic polyvinylidene fluoride( PVDF) membrane was modified by hydrophilic nanometer TiO2to alleviate membrane fouling in MBR. The raw wastewater was taken from a wastewater treatment plant in Changzhou City. After being treated by MBRs with modified or unmodified membrane modules,the respective effluent quality met the first level A criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant( GB 18918- 2002). Although the influent COD concentration was unstable,the removal rates of COD by the unmodified and modified membrane modules were 85% and 94%,respectively. The SS removal rate was almost 100%. The modified membrane module had a slight but non-significant advantage over the unmodified membrane module in TN and TP removal because N and P removal relied mainly on microbial degradation while the membrane separation technology seldom contributed to N and P removal. The membrane fluxes of the two sets of membrane modules both declined after a period of operation time,and recovered by 73% and 78%, respectively,after the online backwashing and chemical cleaning. Both in terms of the effluent quality and membrane antifouling ability,the modified membrane module was better than the unmodified module.