Treatment of Leachate by Recirculating through Dumped Solid Waste in a Sanitary Landfill in Addis Ababa, Ethiopia

Leachate recirculation is one mechanism of leachate treatment that enables both stabilization of leachate and the damped solid waste by enhancing easy movement of nutrient and the required moisture for microbial action within... [ view full abstract ]

Leachate recirculation is one mechanism of leachate treatment that enables both stabilization of leachate and the damped solid waste by enhancing easy movement of nutrient and the required moisture for microbial action within a short period of time than a conventional landfill. Having this, two Poly vinyl chloride pipes compacted with a similar raw material composition and working with 4mL/min and 8mL/min leachate recirculation flow rate were continuously operated for nine (9) consecutive weeks in order to study the effect of leachate recirculation on the quality of leachate. Furthermore, ammonia-nitrogen level found in leachate from bioreactor landfill is much higher than that found in conventional landfill. So, an effective in-situ treatment of this pollutant would be very advantageous, potentially resulting in both environmental and economic advantages. To overcome this problem, the removal efficiency of leachate recirculation on ammonia nitrogen was considered by creating aerobic, anoxic and anaerobic layers in each column from the upper to bottom side. Consequently, the operation resulted an initial concentration increment at the beginning in each study parameters except for that of pH associated with addition of leachate and at the end of the experiment 84.32% BOD, 82.24% TS, 88.97% COD, 79.2% NH4+-N and 94% Cu removal efficiency in R1 that operate at 4mL/L, while 66.45% BOD, 75%COD, 62.98% TS, 67.47% NH4+-N and 79.32% Cu removal efficiency in R2 were obtained mainly due to anaerobic degradation and varies physical and chemical process incorporated inside the reactors.
All in all, even though leachate recirculation is a time taking process it is said to be a promising in-situ leachate treatment and landfill waste stabilization mechanism if it is operated in a controlled manner even for old landfill leachate.
Key words: Leachate, Leachate recirculation, in-situ treatment, landfill waste stabilization