Preliminary investigation on effect of different constructed wetland substrates on capacity of removal of TOC in wastewater

Key words: 
• constructed wetland /
• substrate /
• total organic carbon /
• purification

Abstract: The effect of quantity and components of carbon in substrates on the removal rate of TOC in wastewater was investigated by four substrates or ratio to different substrates. Results showed that carbon was released from four substrates, and the quantity of the released carbon was different following the order of mixture of sand, soil and peat > soil > mixture of soil and sand > sand, when concentration of total organic carbon (TOC) in wastewater was 27 mg/L. The more of carbon was released from substrates due to the higher concentration of carbon in substrates. The removal rate of TOC for three substrates could be summarized as following: soil > mixture of soil and sand > sand. The substrates with higher removal rate of TOC resulted from the higher microbial activity which was related to the higher concentration of carbon in substrates. However, TOC concentration in wastewater from mixture of sand, soil and peat at 12 d was increased due to relatively higher concentration of the stabilization combination organic carbon in peat. The capacity of removal of TOC was influenced by concentration and composition of carbon in substrates, and the higher microbial activity was related to the higher concentration of the easily decomposed organic carbon, which resulted in the higher removal rate of TOC.