The present study was conducted to treat primary and secondary treated sewage for its reuse in irrigation, soil enrichment and aquaculture activities. The study involves treatment of this sewage through a subsurface horizontal gravity-fed gravel filter bed with an area of 35 m2. The effluent was then subjected to filtration by zeolite medium and disinfection by inline electrolytic production of chlorine. In order to provide pathogen-free water, an anodic oxidation (AO) disinfection system was implemented, treating a flow of up to 10 m3/d. The gravity-driven constructed wetland and solar-driven disinfection systems were evaluated for their treatment capacity for various physico-chemical and biological parameters. The wetland removed almost 84% of the nitrate (NO3−) and 77% of the phosphate (PO43−). Five-day biological oxygen demand was reduced from 48 mg/l to 10 mg/l from the secondary treated wastewater. The wetland was able to remove 65–70% of bacteria in the wastewater, whereas the AO disinfection system removed the bacterial content to below the detection limit. The implementation of the systems will provide a suitable option for the treatment of wastewater in a very economical and sustainable way.

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The purification of the primary treated domestic sewage was performed in the present study through the horizontal sub-surface flow constructed wetland (CW) of 10 × 3.5 m dimension. The study was performed using three setups of CW 1 (Unplanted CW), CW 2 (CW planted with macrophyte Typha latifolia), and CW 3 (CW planted with two species of macrophyte T. latifolia and Commelina benghalensis). The purification experiments were performed by converting one type of CW into the other form sequentially, i.e., CW 1 was built first and after the experiments, it was converted into CW 2 and then CW 3. The CW was filled with a layer of coarse and fine gravel of 70 cm depth as filter media in 1:2 ratio. Each set of wetland was operated for 3 months (12 wk) during which the treatment performance of wetlands for basic physicochemical parameters was evaluated. The CW was operated in continuous mode at an average hydraulic loading rate of 250 L h− 1 and the treated effluent was analysed twice every week at four different sampling points having hydraulic retention times (HRT) of 12, 24, 36 and 48 h for important sewage quality parameters All the three setups of CW were able to clean the primary treated sewage significantly. Among the three sets of wetlands used, CW 3 was the best performer removing 79, 77, 79, 79, and 78% of biochemical oxygen demand, chemical oxygen demand, nitrate, ammonia, and phosphate respectively in 48 h HRT. Among the three sets of wetlands, the CW 3 removed the highest percent of total coliforms, fecal coliforms, and E. coli as 64, 61 and 52% respectively.

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