In this paper, we discuss the effect sewage sludge (SS) application has on the contamination of polycyclic aromatic hydrocarbons in fertilized soils and groundwater. Morver, the contents of these compounds in plant biomass was analyzed. For six months, composted sewage sludge was introduced into sandy soil. The research was conducted under lysimetric experiment conditions with the possibility of collecting soil leachate in natural conditions. The following doses of sewage sludge were used: 0, 10, 20, 30, and 40 t/ha calculated per experimental object containing 10 kg of sandy soil. The examinations were carried out within a three-year time frame. Dactylis glomerata grass was grown on the fertilized soils. Every year, the content of polycyclic aromatic hydrocarbons (PAHs) was collected from fertilized objects and analyzed in soil leachate, which can contaminate surface water. The following six polycylic aromatic hydrocarbons defined by Polish standards were determined: benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, and benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene. Further, the content of PAHs in soils and the bioaccumulation of these compounds in cultivated plants were evaluated after each year. The results of the study showed that the increase in the dose of sewage sludge used for soil fertilization led to the rise in the amount of polycyclic aromatic hydrocarbons analyzed in the soil. The compounds migrated to cultivated plants. This phenomenon was observed especially in the first year following soil fertilization with sewage sludge. Excessive accumulation of PAHs (especially benzo(a)pyrene) was observed in plant biomass in the first year of a lysimetric experiment after sewage sludge fertilization with doses greater than 10 t/ha. The increase in bioaccumulation of this compound in plant biomass compared to control objects was 138%, 288%, and 505% after application of 20, 30, and 40 t/ha, respectively. Fertilization with sewage sludge did not cause contamination with PAHs in water leachates from the soils.

This paper presents an analysis of the operation of the water supply system. The analysed network provides water to six small towns. The water supply network covers rural areas of approximately 50 square kilometres with a total of 6130 inhabitants (2020). The area is characterised by relatively large differences in elevation. The water-pipe network supplies water mostly to family housing, public utility buildings, recreational buildings, service and craft entities, religious buildings, and commercial facilities and farms, including breeding farms. The network is supplied from one deep water well and a centrally located water supply tank. A hydraulic model was used for the analysis. The model was developed using the Epanet program, based on numerical and operational data. After validation, selected measurement points were used to calibrate the model. Furthermore, a series of simulations were performed to illustrate the network operation for variable water supply and demand conditions. Single-period analysis was used for modelling due to the type of data obtained. The model allowed for the determination of the head of pressure in the network points and flows in particular sections for the operation parameters studied. The analysis showed that at present, the network is not operating stably. In the case of average demand, water is supplied to all users, but there are areas in the network characterised by high pressure. On the other hand, during maximum water demand, due to the limited water supply to the water reservoir, from which most of the network is supplied, there are water deficiencies that cannot be compensated for by the operating pumping system.

Organic compounds, which are considered water pollutants, have the ability to react with chlorine or other oxidants leading to the formation of products which pose a significant threat to human health. Humic substances play an important role in the formation of disinfection by-products. Therefore, the removal of organic compounds in the process of water treatment is of great importance. The application of ultrasound initiates a number of physicochemical processes in water which can be used in water treatment technologies, e.g. coagulation or adsorption. These methods, as well as the ion-exchange process, are applied in order to remove organic contaminants. With reference to the theoretical fundamentals of ultrasound, some sonochemical processes can result in a decrease in the content of color organic compounds in water. Increasing the intensity of ultrasonic field enhances the occurrence of sonochemical processes including the destruction of high-molecular organic compounds or the oxidation reactions with...

This paper analyses the operation of a water supply system located in the Silesian Voivodeship, serving six small localities covering a rural area of about 50 km² with a total population of 6130. The region’s varied elevation presents challenges to system performance. A hydraulic model was developed in EPANET, then validated and calibrated based on selected measurement points. Previous studies revealed that the network operates under unstable conditions. Although all users receive water under average demand, some areas experience excessive pressure. During peak demand, water shortages occur due to limited inflow to the main reservoir, which the existing pumping system cannot compensate for. In response, the validated model was used in this study to propose a reconstruction strategy to ensure a reliable water supply under all demand conditions. The analysis focused on the introduction of new water intakes, identifying their required capacity and optimal locations. It has been demonstrated that the inclusion of a new water intake positively impacts the stability of the water distribution network, and that a hydraulic model is a valuable tool for supporting the selection of its location. Hydraulic convergence of the model was necessary to optimize and evaluate the proposed solutions. As part of the selection criteria, two parameters were analysed: the percentage of nodes with pressure below 20 m H₂O, and the percentage of nodes where the pressure exceeds 55 m H₂O. Among the evaluated options, the most effective solution was intake no. 1, directly connected to a DN 160 transmission pipe supplying the area with the lowest recorded pressure. The upgraded system operates stably and meets the demands of all users. The obtained results provide valuable support for water utility management in making decisions on the development and operational optimization of water supply networks.

Many publications point out to sewage sludge as a significant sources of polycyclic aromatic hydrocarbons (PAH). Some authors note that the amount of PAHs in plants increases as their concentration in the soil increases. It was often believed that as they are high-molecular compounds, their ability to migrate to plants is limited. In their studies, the authors of the present work took note of the contents of PAHs in sewage sludges used for agricultural purposes. They were used to fertilize a sandy soil in a dose of 10, 50, 100 and 200 t/ha, respectively. The tests were conducted in pot cultures under natural conditions. Osier willow (salix) and dactylis were grown on the sludge-soil mixtures. The use of sewage sludges for fertilization caused a significant increase in the contents of polycyclic aromatic hydrocarbons in the soils. The application of manure for fertilization resulted in the lowest increase in the contents of these components in the fertilized grounds. It was also found that fertilization wi...