Efficiency of Cyperus corymbosus and Eleocharis dulcis in constructed wetlands for municipal wastewater treatment

Abstract

The purposes of this study were to investigate the efficiency of two emergent plants, Cyperus Corymbosus (chufa) and Elcocharis dulcis (spikerush), in constructed wetland with Free Water Surface wetlands (FWS) for municipal wastewater treatment comparing to no plant system, and to find the optimal depth of wastewater to emergent plants for pollutant removal efficiency as compare to the other control experimental units. Twelve experiments of constructed wetland systems were set up at Sakol Nakorn Fisgeries Station. Nine of them were used to study on emergent plants efficiency and three units were used to study on plants height. Wastewater depths in this study were at 0.15 m, 0.30 m. and 0.45 min each three units. Spikerush height at 0.45 m water depth was higher than spikerush at other water depths. Chufa height was no significant difference among three water depths. FWS with chufa at 0.15 m wastewater depth was the best performance for orthophosphate phosphorus, ammonia nitrogen, total suspended solids, total kjeldahl nitrogen and biochemical oxygen demand removal which their efficiencies were over 60 %. FWS with spikerush at 0.15 m and 0.45 m wasterwater depth could reduce ammonia nitrogen, orthophosphate phosphorus, total kjeldahl nitrogen and biochemical oxygen demand over 60 %. At 0.30 m wastewater depth, FWS with spikerush or chufa reduced ammonia nitrogen, orthophosphate phosphorus and total kjeldahl nitrogen over 60 %, too. Conversely, total dissolved solids remoyal in all FWA systems had the efficiencies below 25 %. Comparing of efficiency for pollutants removal at the same wastewater depth, chufa was better than spikerush. It can be concluded that the best and optimum FWS for Sakol Nakorn municipal wastewater treatment was FWS with chufa at 0.15 m wastewater depth.