Application of nonwoven microfiltration membrane on activated sludge final effluent: improving wastewater quality for reuse

Abstract

The application of membrane technology in wastewater treatment for reuse is one of the alternatives to reduce the demand of water in domestic, agricultural and industrial sectors. This study attempts to improve wastewater quality effluent, prior to disinfection, for re-use. Clarifier effluent from a biological nutrient removal (BNR) treatment plant was diverted to a nonwoven membrane pilot filtration unit. It was thus positioned to further enhance the clarifier effluent as a polishing arrangement. Water Quality Index (WQI), Single Factor Pollution Index (Pi), Water Use License (WUL) and removal efficiency methods were used to interpret the water quality data for BNR clarifier effluent and nonwoven membrane permeate. The results showed that this nonwoven microfilter membrane is able to improve wastewater quality from BNR clarifier effluent. Escherichia coli (E. coli) reduction was the highest with a removal efficiency of 90%, followed by chemical oxygen demand 25%, NH4+ 22%, NO3− 12.6%, PO4 7.8%, suspended solids 6.3%. The lowest reduction was electrical conductivity of 5.2%. Permeate results indicated that physiochemical and microbial parameters were complying with the limits of WUL. Pi has revealed that BNR clarifier effluent water quality is medium polluted versus slightly polluted permeate. WQI results for BNR clarifier effluent showed good water quality and the water can be reused for domestic, irrigation and industrial purposes, while permeate WQI results indicated excellent water quality and the water can be reused for drinking, domestic, irrigation and industrial purposes. Outstanding permeate water quality improvement was observed on E.coli counts improving from 4974.48 to 294.33 counts/L. The standard of E.coli according to the WUL at this wastewater care works is 500 counts/L. Results indicate that nonwoven membrane filtration can improve microbial contamination and decrease the demand of chlorine for disinfection of wastewater final effluent. The nonwoven membrane filtration can decrease the water scarcity gap in South Africa for direct water reclamation by improving effluent wastewater.