Comparison Between Integrated Constructed Wetland and MBR Wastewater Treatment Technologies for Gastroenteric Pathogen Removal at NUST, Islamabad

Abstract

The efficiency of both Integrated Constructed Wetland (ICW) and Membrane Bioreactor (MBR) in the treatment of wastewater was assessed using physicochemical, microbial, and molecular studies. Temperature, pH, turbidity, dissolved oxygen (DO), chemical oxygen demand (COD), nitrate (NO2), nitrite (NO3), phosphate (PO4), total dissolved solids (TDS), total suspended solids (TSS), total kjeldahl nitrogen (TKN) and electrical conductivity (EC) were recorded regularly over a period of six months. MBR system effectively reduced COD, TSS, NO3, PO4 and turbidity to a greater extent than ICW with a consistent NEQS compliance level. In comparison, ICW treatment achieved moderate reductions in PO4, TSS and turbidity. Bacteriological examinations were done on Escherichia coli, Salmonella sp and Shigella sp using isolation technique. The initial concentrations of all three species were higher for ICW than in MBR. Overall the MBR 'system achieved higher microbial reductions which is in line with the systems ability to maintain a controlled environment. Real time PCR was then used to confirm microbial findings through quantification of gene copies of its targeted marker genes of E. coli. Both microbial systems experienced a marked reduction in gene concentrations and the MBR showed significantly reductions due to the better operational conditions. This study demonstrates the capability of MBR systems efficiency for treating wastewater and highlights the requirement for appropriate optimizations in ICW system for similar results.