Integration of Constructed Wetland Microcosms with Available Wastewater Treatment Technologies for the Polishing of Domestic Wastewater and Their Potential Reuses

Different constructed wetland microcosm units have been designed in single as well as in combinations to study their performance for domestic wastewater treatment. Further, the integration potential of constructed wetland microcosms technology with up-flow anaerobic sludge blanket (UASB) and fluidized aerobic bed (FAB) reactors as a polishing unit was also studied. From the study, it is evaluated that the maximum removal efficiency of all selected parameters such as biochemical oxygen demand (BOD), total phosphorus (TP), soluble reactive phosphorus (SRP), ammonium (NH 4 + –N), nitrate (NO 3 − –N) and nitrite (NO 2 − –N) was expressed by the mixed planting unit of Pistia Stratiotes and Phragmites karka (Pi + Ph). Several water quality parameters including BOD in the effluent discharged from different constructed wetland microcosm units successfully meet the discharge criteria after three days of retention time. It was observed that both the UASB- and FAB-based reactors alone do not achieve water quality up to discharge standards. However, the available data shows that the performance of the UASB reactors in integration with constructed wetlands in terms of BOD removal reached the highest (up to 98%). Similarly, the removal of other parameters such as chemical oxygen demand (90%), total suspended solids (92%), total nitrogen (89%), NH 4 + –N (70%), and TP (88%) was also recorded as optimum. Consequently, the integration of constructed wetlands systems designed using Pistia stratiotes and Phragmites karka with UASB-based reactors can significantly enhance the performance and may offer a viable integrated wastewater treatment technology.