All over the world, many countries face freshwater problems, and even India is not exempted. As per the CPCB (Central Pollution Control Board) study, India's present scenario is approximately 72368 MLD Municipal wastewater generation all over countries, and approximately 40527 MLD untreated Municipal wastewater generation is discharged directly to surface water bodies (CPCB, 2021). It has led to deteriorating aquatic life of surface water quality, threatened human health, environment, and major water-borne diseases. India faces a problem hues gap exists between treated Municipal wastewater and untreated Municipal wastewater because of lack of funding and management create this large gap (CPCB and DST, 2019& ENVIS). In view of capital cost limitation and minimizing large gap can use the less capital cost and less maintenance technique for the treatment of Municipal wastewater.
Various advanced Municipal wastewater treatment technologies are the solution in this context. Some conventional treatment technology such as stabilization pond, anaerobic filter, green filter, septic tank, sand filtration and Activated sludge process are still in use. Now a day's a new low capital cost, less maintenance cost and eco-friendly constructed wetland (CWs) is becoming popular for the Municipal wastewater treatment. (Abidi et. al., 2009; J. Vymazal, 2003;Molle, p., et. al., 2008; Kouki S. et. al., 2009;Brix, H. and Arias, C.A, 2005; Jian Zhang, et. al., 2014). Constructed wetlands (CWs) are the new artificially engineered system that remove the pollutants load from various types of wastewater (Masi, F. et. al., 2002; Brix, H. and Arias, C.A, 2005; J. Vymazal, 2005; Kouki S. et. al., 2009; Dotro G. et. al., 2015). It has been found to effectively remove pollutants like organic and inorganic contamination, nutrients, pathogens as well as transmitted virus in wastewater bodies and pathogens. (Lesage, 2006 & 2007; Keffala C. and Ghrabi A., 2005; Tanner CC, et. al., 2012; Haiming Wu et. al., 2013; Dotro G. et. al., 2015). Now a days mainly horizontal flow or vertical flow hybrid constructed wetlands (HFHCW or VFHCW) are more used individually for the treatment of municipal and industrial wastewaters (Karathanasis, A.D et. al., 2003;J. García, 2005; Wang, R, et. al., 2012;Abou-Elela, S.I. and Hellal, M.S, 2012). Horizontal flow or vertical flow hybrid constructed wetlands (HFHCW or VFHCW) have been successfully used in industries like fertilizer, textile, dairy, tannery, food and beverages and pulp & paper etc. to removes varieties of pollutants (Abou-Elela, S.I. and Hellal, M.S, 2012; Zurita, F, et. al., 2009;D.A. Yaseen and M. Scholz, 2019). The removal mechanism may include ion exchange, soil adsorption and uptake by plants, chemical precipitation, and anaerobic or aerobic microbial growth or decomposed activity (Karathanasis, A.D et. al., 2003; Keffala C. and Ghrabi A., 2005; Klomjek, P. and Nitisoravut, S, 2005;Molle, p., et. al., 2008;Lesage E, 2006; Zhang, D, et. al.,2009). Constructed wetland (CW) treatment performance can be increased using anaerobic and aerobic processes (Lesage E, 2006; Lesage E, et. al., 2007).
In this study, one lab scale at two-stage Vertical flow followed by horizontal flow hybrid constructed wetland (VFHCW- HFHCW) configuration was used to treat municipal wastewater of the Prayagraj city. Two different plant species, such as Calibanus hookeri and Canna indica red color (Cannaceae), were used to treat actual sewage wastewater collected from the outside and Motilal Nehru National Institute of Technology Allahabad, Prayagraj, India, campus.
This study aims to evaluate the pollutants removal, hydraulic retention time, role of flow, and nitrification from two different types’ plant species. At present, there is lack of proper guidelines in our country India for the design criteria, flow regulation, and Hydraulic retention time (HRTs) for the constructed wet land process. If these guidelines are in place then in future more and more ULBs and small town areas can select the most suitable hybrid constructed wetlands configurations with eco-friendly technology for the treatment of sewage and grey wastewater.