The processes that affect sediment quality in drainage systems show high dynamics and complexity. However, relatively little information is available on the influence of both catchment characteristics and meteorological conditions on sediment chemical properties, as those issues have not been widely explored in research studies. This paper reports the results of investigations into the content of selected heavy metals (Ni, Mn, Co, Zn, Cu, Pb, and Fe) and polycyclic aromatic hydrocarbons (PAHs) in sediments from the stormwater drainage systems of four catchments located in the city of Kielce, Poland. The influence of selected physico-geographical catchment characteristics and atmospheric conditions on pollutant concentrations in the sediments was also analyzed. Based on the results obtained, statistical models for forecasting the quality of stormwater sediments were developed using artificial neural networks (multilayer perceptron neural networks). The analyses showed varied impacts of catchment characteristics and atmospheric conditions on the chemical composition of sediments. The concentration of heavy metals in sediments was far more affected by catchment characteristics (land use, length of the drainage system) than atmospheric conditions. Conversely, the content of PAHs in sediments was predominantly affected by atmospheric conditions prevailing in the catchment. The multilayer perceptron models developed for this study had satisfactory predictive abilities; the mean absolute error of the forecast (Ni, Mn, Zn, Cu, and Pb) did not exceed 21%. Hence, the models show great potential, as they could be applied to, for example, spatial planning for which environmental aspects (i.e., sediment quality in the stormwater drainage systems) are accounted.

E3S Web of Conferences, open access proceedings in environment, energy and earth sciences

The study presents the results of tests aimed at determining variations in concentrations of polycyclic aromatic hydrocarbons (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a, h]anthracene, benzo[g, h, i]perylene and indeno[1, 2, 3-c, d]pyrene) and heavy metals (copper, cadmium, chromium, nickel, lead and zinc) in the sediments from the stormwater sewer system. Results of this study were then compared to Polish regulations and established ecological screening values to determine their potential risk to environment. The results suggest that stormwater sediments are moderately contaminated with PAHs and heavy metals according to domestic regulations and highly contaminated according to ecological benchmarks.

Contaminants bound to suspended solids transported by stormwater pose quantity and quality problems to the water ecosystem. Therefore, it is necessary to carry out an ecological risk assessment. Currently, Polish legal regulations do not require that stormwater sediments should be tested for hazardous substances prior to their removal. Ecological evaluation was performed for polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the sediments from three selected stormwater sedimentation tanks located in urban catchment areas of Kielce city. The purpose this study was to analyze sediments for chemical contaminants and to demonstrate the relationship between contaminant levels and physical attributes of the catchment, including land use, drainage area, age of catchment and impervious surface in the watershed. Levels of PAHs and heavy metals (Cd, Cr, Ni, Pb and Zn) in stormwater sediments were then compared with Polish regulations and ecological screening values to determine their potential risk to environment were established. The results of the current study suggest that stormwater sediments are moderately contaminated with PAHs and heavy metals according to domestic regulations. They are, however, highly contaminated according to ecological benchmarks, which are exceeded several times.

One of the advanced oxidation methods is the Fenton’s reaction which uses a mixture of iron(II) and hydrogen peroxide to generate hydroxyl radicals. The Fenton process efficiency is influenced by a number of factors including the pH, the Fe2+:H2O2 relation or the Fe2+ dose. The aim of the study was to optimize the Fenton method in the application for landfill leachate treatment, with the landfill in Janczyce (Świętokrzyskie Voivodeship) as an example. The sequence of determining the most advantageous conditions for the use of Fenton’s reagent was as follows: A – the pH effect; B – the oxidation time effect; C – the Fe2+:H2O2 relation effect; D – the Fe2+ dose effect. The optimum catalyst/oxidant ratio of 0.125 was determined. The optimum process time of 90 minutes was determined. It was demonstrated that the Fenton process can be effectively carried out already at the pH of 4. A reduction by 75% for the TOC and by 89% for the COD, respectively, was obtained.