Constructed wetlands have been used to treat a variety of wastewaters including landfill leachate. One of the most important advantages of the Constructed wetlands is that it can remove significant amounts of nitrogen, and are less complex that other biological wastewater treatment systems. The main purpose of this study was to treat organic pollution and ammonia present in mature landfill leachate by the use of constructed wetland systems. Research and experimental process were done at pilot scale in the Autónoma de Occidente University Campus (Santiago de Cali, Colombia).
The system consists in four pilot-scale subsurface flow wetlands separated in two different treatment lines (Line 1: Vertical-Horizontal subsurface flow wetlands and Line 2: Vertical-Vertical subsurface flow wetlands). The constructed wetlands were planted with a polyculture of the tropical plants Colocasia esculenta and Heliconia psittacorum and the support media used were 3/8” gravel and gross sand.
The constructed wetlands were operated at continuous flow (Q = 0.173 m3/d) and a theoretical HRT of 7 days each and treating mature landfill leachate for the removal of chemical oxygen demand (COD) and Total Ammonia Nitrogen (TAN). The mature leachate was brought from a closed landfill “Navarro”, located in Santiago de Cali; this leachate presented a concentration of ammonia and COD of 3187 ± 1767 mg/L y 5120 ± 1617 mg/L, respectively.
pH, temperature, conductivity and DO (Dissolved Oxygen) parameters were daily measured in each monitoring point to supervise wetlands operation, and twice-per-week were measure CDO, TAN, nitrates, nitrites, phosphorus, alkalinity and suspended solids in the effluent with the purpose of to analyze the wetlands behavior.
Preliminary results shows that Line 1 present an ammonia and COD removal efficiency of 48% and 76%, respectively, while Line 2 present COD removal efficiency of 59% and 71%, respectively, showing that Vertical-Vertical subsurface flow wetlands configuration has advantages in the reduction of COD and TAN compared to Vertical-Horizontal subsurface flow wetlands configuration.
Keywords: Biological landfill leachate treatment, constructed wetlands, ammonium oxidation process, mature leachate.
6d. Water and sanitation
