Constructed wetland scale model: organic matter and nutrients removal from the effluent of a fish processing plant

Constructed wetlands are suitable for treating industrial effluents due to their low cost and effectiveness, thus preventing the deterioration of waterways witnessed in recent decades at global level. Advances in the study of wetland design are necessary for the development of constructed wetlands. An artificial wetland model with subsurface flow (three replications), Typha domingensis, and hydraulic retention time of 5 days was used. It was designed for the post-treatment of the effluent from a fish processing plant. All samples were taken at the model system inlet and outlet every 21 days for 1 year. Significant removal of nitrogen and organic matter (biochemical oxygen demand and the chemical oxygen demand) was achieved, but phosphorus removal was less than expected. Wetland performance was not affected by seasonal variations in ambient temperature. The increase in the C/N ratio was related with a higher wetland efficiency of organic matter removal. Overall performance for the wetland model under in situ environmental conditions was determined by the intrinsic reaction rate of the system.