Assessment of the environmental impact of sanitary and unsanitary parts of a municipal solid waste landfill

Only seven regional MSWLF in Serbia are considered sanitary, while about 3500 landfills operate without proper pollution control. This paper presents a unique opportunity to evaluate the impact of a closed landfill, and a new sanitary landfill, which are located next to each other. The following methodologies for the landfill impact assessment were applied, based on data from 2012 to 2017: Landfill water pollution index (LWPI) and Nemerow index (PIGW) for groundwater, and the geo-accumulation (Igeo) and ecological risk (ERi) indices and several PAH ratios for soil. The performance of the leachate control system was evaluated using two adapted pollution indices: LPI and the Nemerow index (PIL). According to the obtained LWPI and PIGW values, the quality of groundwater at the new landfill is improving (LWPI = 1.05–2.62; PIGW = 0.52–1.29), while no significant changes were observed for the old landfill (LWPI = 3.06–5.13; PIGW = 2.03–4.78). High concentrations of ammonia nitrogen (1.01–22.74 mg/l), Fe (0.76–57.11 mg/l), Ni (5.80–230.09 μg/l), Pb (4.2–202.4 μg/l) and ∑PAH16 (150.93–189.55 ng/l) show the strong influence of the landfill on the groundwater quality at the old landfill, indicating the need for additional remediation action. High concentrations of Ni (21.9–133.0 mg/kg) and Cr (8.5–277.0 mg/kg) in the analyzed soil compared to other studies, as well as moderate Igeo values (IgeoNi = 0.36–1.88; IgeoCr = −1.20–1.52), raise concern and suggest the need for further monitoring. The high ERi (158.6–295.0) and Igeo values (0.91–2.30) of Hg show significant potential ecological risk. LPI and PIL values for early methanogenic phase leachate demonstrates the need to improve the leachate treatment system. The monitoring data and applied pollution indices indicate that Cr and As should be added to the EU Watch List of emerging substances, at least regarding EU potential candidate countries.