Organic matter and nutrient removal in a sequencing baffled steep-flow constructed wetland system

Abstract

Objective: The performance of Pistia stratiotes (water lettuce) for the removal of organic compounds and nutrients in a sequencing baffled steep flow reactor was investigated in this study. Methodology: The reactor consist of five horizontal compartments (C1-C5) of various sizes with a steep-wise water depth for rapid wastewater flow. Acrylic made baffles were installed in reactor zones C1, C2 and C4 to prevent short circuiting. Pistia stratiotes were planted on the surface of each compartment of the reactor. Wastewater from a sewage effluent was used in this study and was applied to C1 at a high, fixed HLR of 10.2 m3/m day-1 (225 L day-1) and fluctuating Organic Loading Rate (OLR) and Ammonium Loading Rate (ALR), respectively. Reactor performance was monitored for a period of 7 days. Results: Results show that the COD removal fluctuated between 7.1-54% from day 1-5. No COD removal was observed in day 6 and 7. The NH4+-N removal also fluctuated between 13-94% from day 1-7. Phosphorus removal were found to fluctuate between 11.5-48% from day 1-7. Conclusion: The fluctuation noticed in the effluent concentration of each parameter could be attributed to the effect of the fluctuating influent feed. The reactor nutrient removal capacity clearly indicates that it could serve as a suitable phytoremediation configuration.