Removal of COD from synthetic wastewater in vertical flow constructed wetland.

Abstract

Three vertical flow constructed wetlands, i.e., system A (planted with Pennisetum sinese Roxb), system B (planted with Pennisetum purpureum Schum.), and system C (without plants as the control) were constructed to estimate the contribution of substrates, plants and microorganisms to organic matter removal. The organic compounds accumulated in the substrate in systems A, B, and C were 12.03%, 11.91% and 9.4%, respectively. Synergistic utilisation of organic compounds by microorganisms and plants in systems A, B, and C were 80.95%, 81.58%, and 80.11%, respectively. Substrate interception and adsorption of organic compounds in plant systems A and B were more extensive than in the non-plant control system C. The total accumulative and absorptive capacity of systems A, B, and C was as follows: B (2,713 g) > A (2,698 g) > C (2,076 g). The amounts of insoluble organic accumulated on the upper substrates of the three systems showed the order C > A > B. No constructed wetland clogging occurred for A and B systems during the experiment, while system C suffered clogging in early September. Therefore, substrate blockage may be related to the type of organic compound accumulated. Accumulation of insoluble organic matter is the direct cause of system blockage. This article is protected by copyright. All rights reserved.