MICROBIOLOGICAL ANALYSIS OF MEMBRANE BASED SEPTIC TANK EFFLUENT AND ITS REUSE

Abstract

With declining trend in global water resources wastewater reclamation and reuse has gained considerable importance worldwide. The present study was conducted with the objective to reuse domestic wastewater treated by using membrane technology for crop irrigation. Membrane based septic tank was designed (MBST) by submerging a woven fiber microfiltration membrane module (WFMF) to treat domestic wastewater. To evaluate the performance efficiency of MBST, effluents were characterized for microbiological and physical parameters. Removal of organics (COD), turbidity, nutrients deduction (P and N) and indicator bacteria (Escherichia coli) removal efficiency was about 73, 96, 48 and 88 % respectively. Three crops Triticum aestivum (wheat), Coriandrum sativum (coriander) and Mentha arvensis (mint) were irrigated with treated MBST effluents under controlled conditions. All the crops were also grown using untreated wastewater (after primary settling) and tap water for comparative study. Upon maturity, the roots, shoots and leaves of these plants were aseptically removed for microbiological analysis. Two bacterial strains Escherichia coli and Salmonella sp. were isolated from MBST treated effluents and crops which were irrigated with these effluents. These bacterial strains were identified using biochemical test, 20E API kit and 16S rRNA gene analysis. A remarkably positive effect was observed on removal of bacterial load (p<0.001) and helminthes eggs from effluent treated by MBST. While on the other hand increase in germination percentage, dry biomass, root and shoot length and reduction in bacterial strains was observed in crops irrigated by MBST discharge in comparison with untreated wastewater. The current study revealed that wastewater treated with MBST with UV disinfection may be used to meet the irrigation requirements and better yield.