The most important problem related to the collection of waste in landfills is the presence of harmful substances contained in leachate resulting from the flow of atmospheric precipitation through the deposited waste, which may end up in the soil. As a result, the soil’s chemical degradation occurs, which may result in a change in the structure and activity of microorganisms. In addition, leachate can end up in groundwater that may be hazardous to human health. The aim of the study was to determine the effect of landfill leachate on selected physicochemical, biological and biochemical properties of soils. The cytotoxicity of soil filtrates (SF) in human cell lines and their effect on apoptosis were also analyzed. In the pot experiment, leachate was added to the soil in two doses: 50LL (50% of the N dose) and 100LL (100% of the N dose). Selected physicochemical properties, activity of enzymes, diversity of bacteria and fungi by the T-RFLP approach were determined in soil samples. As a result of the analyses, it was found that LL causes an increase in the activity of dehydrogenases and a decrease in β-glucosidase. In the soils treated with LL, bacterial T-RF (144) bp, (179) bp and (413) bp were specific, while fungal were T-RF (390) bp, (441) bp and (595) bp. Potentially cytotoxic effects of SF and reduction in apoptosis in neoplastic cells were found in in vitro tests. LL and SF are complex matrices with a variable composition, which means that their impact on the soil environment must be constantly monitored.

The paper deals with the study on the use of the Fenton and photo-Fenton process for the treatment of landfill leachates from a stabilized landfill site. The effluents were characterized by pH 8.1, color: 1320 mg Pt/L, COD 1670 mg/L, BOD5 155 mg/L, conductivity of 10.3 mS/cm, absorbance UV254...

In this study, the application of ozonation and ozonation with hydrogen peroxide processes for landfill leachate treatment was investigated. The effluents were characterized by COD 710 mgO₂/dm³ and BOD₅ 72 mg O₂/dm³. According to the adopted indicators, the determined BOD/COD ratio of 0.1 in raw leachates indicates a stabilized landfill. Ozone was applied at doses of 0.15 - 0.6 gO₃/dm³, and hydrogen peroxide at such doses to keep the weight ratios of H₂O₂/O₃ 0.4 - 1.6. The maximum COD and UV absorbance removal was respectively 29% and 51% by applying a high ozone dose of 0.6 gO₃/dm₃. After oxidation, the ratio of BOD/COD was increased from 0.1 up to 0.3. It has been shown that by using hydrogen peroxide in ozonation, organic compounds expressed as COD can be efficiently removed from the effluents. The best conditions for the H₂O₂/O₃ process were obtained with a H₂O₂/O₃ ratio of 0.8 and ozone dose of 0.6 gO₃/dm³. Under these conditions, the removal efficiency of COD was 46%.

Leachates from landfills constitute a very complex environmental matrix with potentially toxic properties for both the environment and humans. Due to this fact, toxicological tests were carried out on landfill leachate (LL) obtained from the local landfill in Hryniewicze (Poland). The analyses included physicochemical studies of leachates and their impact on soil and plants, and studies conducted in bacterial models and human cell models. The results obtained indicate high contents of metals and organic matter, especially dangerous PAHs, in the tested leachate. This results in the influence of LL on changes in the content of assimilation pigments and oxidative stress observed in plants grown in soil fed with leachates. The effect of leachate on the growth of Sporosarcina pasteurii, Staphylococcus aureus, Lactobacillus rhamnosus, Saccharomyces boulardii and Candida albicans varied depending on the strain and LL dose. A particularly significant increase in proliferation after exposure to LL was noted for S. aureus. In studies conducted on human cancer cell lines representing three types of glioblastomas and one type of colorectal adenocarcinoma, a particularly significant increase in the viability of cells treated with LL was noted for the DLD-1 cell line. The results obtained, especially the stimulation of the growth of cancer cells and an increase in the number of pathogenic bacteria, indicate the potential toxic properties of the tested leachates. This is confirmed by the high level of oxidative stress in plants. The results indicate the need for continuous monitoring of waste landfills and leachates generated there.

This study investigated the use of weathered halloysite as an ion exchange material for ammonium removal from water. The study was conducted under static and dynamic conditions. The influence of such parameters as the preliminary concentration of ammonium ions, dose of halloysite, and pH was examined in periodic studies. The ion exchange capacity of weathered halloysite under various regeneration conditions such as concentration, excess of regeneration solution and the pH at which the regeneration was performed was also determined. The effect of flow velocity, initial NH₄⁺-ions concentration was studied in column tests and the weathered halloysite’s ion -exchange capacity was also determined. The best results of ammonium ion removal were obtained at pH 6. The equilibrium isotherms were described using the Langmuir and Freundlich models. The results of periodic studies show a good fit for the data of both models, with Langmuir isotherms reflecting the removal of ammonium ions better. A good match for the data (R² > 0.99) was provided by a pseudo second-order kinetic model. The obtained results indicate that a properly prepared halloysite can be a useful mineral for the removal of dangerous substances, such as ammonium ions, present in natural waters.