Small-Scale Wetland Units for Domestic Greywater Treatment

Abstract

Constructed wetlands (CW) are eco-friendly systems which mimic the functions of natural wetland. It is low-cost alternative system for the treatment of wastewater even up to domestic level. Therefore, this study was designed to assess the feasibility of pilot scale CW units on greywater treatment at domestic level. The sub-surface flow constructed wetland units were designed using small plastic containers with the size of 55cm length, 25cm width, and 28cm height. Three types of plants, Vetiver (Vetiver iazizanioides), Water spinach (Ipomoea aquatic L.) and Lasia (Lasiaspinosa L.) were used. One container was used without plant as a control. The experiment was conducted in a Completely Randomized Design (CRD) with three replicates in greenhouse conditions during two months period by using synthesized wastewater at a flow rate of 0.73L/h. The Hydraulic Retention Time of the system was 41 hours. The quality of the influent and effluent were monitored at two weeks interval by analyzing water quality parameters such as Biological Oxygen Demand (BOD5), Total Dissolved Solids (TDS), pH, Electrical Conductivity (EC), PO4-3-P, NO3--N and NH4+-N. According to the results, removal efficiency of contaminants increased with monitoring period. Vetiver showed significantly (p<0.05) higher RE for BOD5, PO43--P, NO3--N, NH4+-N by 46%,71%,83% and 89%, respectively compared to other plants. Hence, it can be concluded that the pilot scale CW units are a feasible technology for greywater treatment at domestic level with Vetiver as the wetland plant since its' dense fibrous root system leads to removing more pollutants from the domestic wastewater.