Constructed Wetlands for Wastewater Treatment: Temperature, Substrate and Reed Dependence

An experiment was designed to study three parameters of a bench scale constructed\ud wetland, temperature, reeds presence and chemically active substrate materials. Phragmites\ud Australis were planted in two of four beds and two were left unplanted. Two substrates\ud were used, sand with Fe2O3 as the chemically active material and Solite as the inert\ud material. The beds were left outside over a period of six weeks with a simulated waste\ud water flowing through the beds with a 24 hour detention time. Recorded data were\ud extremely inconsistent. BOD removal data were compared to hours of sunlight to examine\ud the transient response of the system as spring arrives. Data were inconclusive in that test,\ud showing a vague downward trend contrary to expectations. Absolute BOD removal for all\ud beds was around 50%. Solite exhibited slightly better removal rates than the sand.\ud Phosphorus removal between the beds was compared, and sand with rust (Fe2O3)\ud performed more effectively. From analysis of variance it was determined that the BOD\ud removal differences were not statistically significant, while Phosphorus removal was. Data\ud for beds with reeds performed less well than beds without reeds, suggesting that\ud preferential flow patterns along root-paths may have been established. It was noted that the\ud approximations of a natural wetland in the experiment were crude and divergent with the\ud goals of natural water treatment