Physico-chemical characteristics of leachate from landfills and its impact on surface water quality: case study in Osmaniye/Turkey

Landfill is the most preferred method of municipal solid waste (MSW) disposal due to its low cost and easy disposal procedure. However, the production of highly polluted leachate is a major disadvantage of landfills. Landfill leachate is the main byproduct of the Domestic Solid Waste (MSW) degradation process. Treatment of landfill leachate with high organic and inorganic contents requires combined techniques using modular or multi-stage units based on targeted pollutants. Therefore, it is necessary to determine the leachate properties in order to select suitable treatment methods. This study includes the evaluation of the physico-chemical properties of MSW landfill leachate and its effect on surface water quality in terms of receiving environment discharge standards. For this purpose, a total of 16 physical and chemical parameters that require fulfillment of receiving environment discharge standards in leachate for "Solid Waste Evaluation and Disposal Facilities" were analyzed and evaluated. The leachate analyzes were carried out quarterly, covering a total of 7 periods (2017-2019-21 months). Mean concentration values in heavy metal analysis results (mg/L) were obtained as 2.81, 0.513, 0.42, 0.14, 0.051, 0.013, 0.0018 for Fe, Zn, TCr, Cr6+, Cu, Pb and Cd, respectively (Fe > Zn > TCr > Cr6+ > Cu > Pb > Cd). The mean metal concentrations in the leachate were found to be quite low and below the receiving environment discharge standards due to the low solubility of metals at alkaline pH. The values show that they are in agreement with other data in literature. In the study, the maximum and minimum COD values were determined as 8663 and 973.4 mg/L, respectively. The mean COD value was calculated as 5342.34 mg/L. The mean SS, TKN, TP, oil and grease values were found to be 342.36, 838.16, 10.03, 105.63 (mg/L), respectively. The results revealed that some parameters such as COD and TKN, TP, Oil and Grease, SS and EC do not meet the receiving environment discharge standards for class (II) storage facilities. When the results are evaluated, it is seen as a positive approach to return the leachate to the lot or to treat it with appropriate treatment methods in order to meet the receiving environment discharge standards.