Evaluating the multiple benefits of constructed wetlands in the restoration of rural village ponds in the tropics

Abstract

Constructed wetlands (CWs) have been widely recognized as a cost-effective and environmentally sustainable technology for the treatment of domestic wastewater. In this study, the water quality of a CW integrated pond in Ibrahimpur village in sub-tropical India has been compared with a control pond in Masahi Kala village. Field investigations evaluated the performance of a CW system in enhancing water quality, ecological health (via macroinvertebrate analysis), and reducing greenhouse gas (GHG) emissions. The treatment chain comprises of a settling chamber (≈7 h HRT), CW (≈3.7 days HRT), and pond (≈190 days HRT) resulting in a notable reduction of BOD (83 %), COD (81 %), NH₄-N (82 %), and PO₄-P (75 %) concentration. Moreover, a 3-log reduction in average total coliform counts and a 4-log reduction in E. coli counts were observed. Mean CH₄ and CO₂ concentrations measured in Masahi Kala pond (control) were an order of magnitude greater than those observed in Ibrahimpur pond, i.e.,7.66 mg CH₄-C L⁻¹ and 7.69 mg CO₂-C L⁻¹ in Masahi pond compared to 0.237 mg CH₄-C L⁻¹ and 0.933 mg CO₂-C L⁻¹ in Ibrahimpur pond. The Ibrahimpur pond was dominated by Chlorophyta (on average 57 % of biovolume) algae, whereas, the Masahi pond was dominated by Euglenophyta, a bioindicator of organic pollution. The findings underscore the multifaceted benefits of CWs in revitalizing rural village ponds, demonstrating their effectiveness as a sustainable solution for ecological restoration and wastewater management.