TREATMENT OF STABILIZATION POND EFFLUENTS USING HORIZONTAL SUBSURFACE FLOW CONSTRUCTED WETLAND PROCESS

Stabilization ponds are commonly used for wastewater treatment purposes in rural small regions due to low-cost and easy operation. During spring and summer, algae bloom in the lagoon is inevitable, which may cause low effluent quality. As a consequence, algae decomposition can deplete oxygen in the receiving environment. Therefore, high algae and chemical oxygen demand (COD) concentrations in the effluent of stabilization ponds restrict its discharge and use for irrigation purposes. In this context, this study aims at evaluating the efficiency of a low-cost horizontal sub-surface flow constructed wetland process to improve the quality of stabilization ponds effluent. The pilot scale constructed wetland removed around 56 +/- 15% total COD, 40 +/- 13% soluble COD, 90% suspended and volatile suspended solids and 57 +/- 22% total nitrogen from stabilization pond effluent. The pollutant concentrations in constructed wetlands effluent were always below the values given in Turkish wastewater discharge guidelines. Therefore, the constructed wetland systems are effective for polishing the stabilization pond effluents.