Effects of Operational and Cleaning Practices on Membrane Fouling during the Reclamation of Secondary Effluent from a Wastewater Treatment Plant

摘要

Effects of three different operational changes on membrane fouling were evaluated for arnwastewater secondary effluent reuse facility: addition and no addition of a coagulant (ferricrnchloride), an accidental high chlorine (sodium hypochlorite) dose, and an extended hydraulicrnbackwash. Two different types of membrane modules were compared: one with 3 yearsrnoperation and the second with 9 months of operation at the time of data collection. Fouling ratesrnranged between 2 to 3 times higher during no ferric chloride addition than the ferric chloridernaddition. Chemical cleaning frequency was reduced by approximately 5 times during the ferricrnchloride addition for older membranes, while it did not change for newer membranes. Highrnchlorine dose had slightly improved membrane permeability for newer membrane, and reducedrnthe transmembrane pressure (TMP) for both types of membranes. Additionally, extendedrnbackwash had shown significant improvement in membrane permeability and reduction in TMPrnfor both types of membranes. Membrane fouling index (MFI) values indicated that coagulantrnaddition had greater impact on performance recovery after hydraulic backwash for olderrnmembranes than newer membranes. Moreover, MFI values also indicated that extendedrnhydraulic backwash can lower chemically irreversible fouling.