Treatment of Domestic Wastewater Using Duckweed Plant

Abstract

Pollutants removal from domestic wastewater by growing Lemna gibba, a promising duckweed identified in previous studies, was investigated under laboratory conditions. The duckweed wastewater treatment system used in this study consists of sedimentation and Duckweed tanks. Samples from the wastewater media in both sedimentation and duckweed tanks were analyzed for Temp., pH, BOO, COD, TSS, TDS, EC, NH3-N, N02-N, N03-N, Fecal coliform, and Total bacteria count. The average removal efficiencies of TSS, BOO, COD, NH3-N, N02-N, N03-N, TN, TP, TDS, EC, Fecal coliform bacteria, and Total bacteria count for sedimentation tank were 55%,27%, 24%, 26%, 30%, 27%, 19%, 32%, 6%, 4%, 50%, 39%, respectively. While the average removal efficiencies of BOO, COD, TSS, TDS, EC, NH3-N, N02-N, N03-N, TN, TP, fecal coliform, and total bacteria count for duckweed tank were 60%, 54%, 63%, 9%, 5%, 63%, 64%, 63%, 63%, 65%, 96%, 98% at 66th day running time. The analysis of plant tissue was done. The rates of nitrogen and phosphorus uptake by duckweed growing in the system were 0.173 g/m2 d and 0.032 g/m2 d, respectively. The observed duckweed growth rate was close to 1.2 g/m2 d. Wastewater concentration and climate conditions had direct impact on the duckweed growth and nutrient removal in the tank.