Treatment of Domestic and Industrial Wastewater with Constructed Wetland—A Review

Constructed wetland (CW) is an engineered version of a natural wastewater treatment. It can apply in a sustainable way for domestic (DWW) and industrial wastewater (IWW) treatment with low capital, operational, and maintenance cost. Pollutant removal efficiency of CW is affected by substrate, plants, microbes, temperature, hydraulic loading rate, and hydraulic retention time (HRT). Removal of nitrogen increased with intermittent aeration, back recirculation of little quantity of treated water, use of ion exchange substrate, and microbes. Removal of organic compounds increased with batch loading of wastewater and substrate with sufficient porosity. Substrate with iron, aluminium, and calcium increased the phosphorus absorption. Higher temperature favours the plant and microbial growth. Area requirement can reduce with various design modifications. Wetland can be constructed at 1/3rd cost and can be maintained at 1/5th cost than conventional wastewater treatment. Author compared more than eighty research studies to find the best possible solution for DWW and IWW treatment. Professionally designed CW can treat DWW at 3–4 days HRT and removes up to 81–92% COD, and 70–89% BOD. Hybrid CW with longer HRT performs better in treatment of IWW. Hybrid CW can remove 76–99% colour from textile wastewater, up to 96% colour form pulp and paper mills wastewater, 70–99% COD from winery wastewater, and 68–93% COD from dairy wastewater.