Lecheate physico-chemical parameters removal efficiency and possible alternative treatment options to Kiteezi landfill treatment facility

Abstract

Sanitary landfills generate large quantities of highly polluted leachate, which is a major environmental, economic and social concern. Further, the treatment of landfill leachate constitutes a challenge that may vary considerably depending on the age of the landfill. This study was aimed at evaluating the removal efficiency and determine a best treatment option for the landfill leachate to meet Uganda's national standards for safe effluent discharge to the surrounding environment. The specific objectives were to; determine the efficiency of the current treatment plant at Kiteezi in terms of leachate quality and determine the best treatment option for the treatment of the leachate from the Kiteezi landfill. The performance evaluation of the Kiteezi activated sludge facility included, a weekly assessment of the physico-chemical parameter reduction efficiency of the raw, and treated leachate from March 5 to July 23, 2020. The best treatment option was established by comparing two treatment options: lateritic soil and activated carbon amended with sand, by varying the combination of their particle sizes (0.25-0.5 mm, 0.5-1 mm, and 1-4 mm) with their column lengths (30 cm, 45 cm, 60 cm, and 75 cm).The study showed that the current Kiteezi landfill activated sludge treatment was only effective for the treatment of the turbidity (90.4 ± 6.4 %). This was due probably to the halving of the total phosphorus (TP) and total suspended solids (TSS), which were very high in the raw leachate. For other Physico-chemical parameters, the values in the effluent increased. For example, the value of the pH was 8.75 ± 0.13 at the inlet and 9.67 ± 0.17 at the outlet. The concentration of total nitrogen (TN) was 190 ± 50.2 mg/L and increased to 6,749 ± 1,595 mg/L. For the chemical oxygen demand (COD) and the color of the leachate, their values remained more or less the same before and after treatment; color was 15,182 ± 2,649 PtCo at the inlet and 16,008 ± 1,710 PtCo at the outlet, and COD was 31,362 ± 5,844 mg/L at the inlet and 32,218 ± 963 mg/L at the outlet. This poor treatment efficiency could be due to the composition of the sludge as well as the lack of oxygen in the aeration tank. For the best treatment option, this study showed that lateritic soil was more effective than activated carbon in reducing all the Physico-chemical parameters of the leachate. The effluent quality met the effluent discharge standards set by the National Environment Management Authority of Uganda. The maximum reduction efficiency was achieved with the combination column length of material of 75 cm associated with particle size range 0.25-0.5 mm.