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The problem of wastewater discharged from facilities for soilless plant cultivation is a worldwide problem. So, there is a strong need to find a simple, maintenance-free technological solution. Such a solution may be the use of biofilters or constructed wetlands with “active” filling, which will be a source of carbon for denitrifying organisms. The aim of this study was to evaluate four different types of materials—Oxytree wood chips (Paulownia Clon in vitro 112®), biobased polybutylene succinate derivatives (BioPBS FZ91PB and BioPBS FD92PB), and beech wood chips—as biofilter media and as solid exogenous carbon sources. The highest efficiency of denitrification and dephosphatation (43.11% and 42.48%, respectively) was characterized by the biobased polybutylene succinate FD92PB. The lowest removal efficiency of phosphorus compounds was achieved for beech chips—25.23% and BioPBS FZ91PB—26.42%. The lowest denitrification efficiency—8.8%—was achieved by Oxytree wood chips. The extent of organic matter (COD) repollution in the treated wastewater requires further study. Wood chips were found to release less COD than biobased polybutylene succinate. The research results showed that all tested materials can be a source of carbon in soilless tomato cultivation wastewater treatment. This is a good starting point for further research on selecting appropriate process parameters and creating new solutions for reactor construction.

The use of food waste disposers in gastronomical facilities influences municipal wastewater composition. Ground food waste poses problems in the operation of the sewerage network and generates high electric energy consumption in wastewater treatment plants (WWTPs). This study aimed to determine, for five towns with a PE (Population Equivalent) ranging from 4000 to 220,000, the volumes of catering waste discharged to the WWTPs. The towns differed in the number of inhabitants, beds in hotels, and catering places. The calculations were undertaken based on data received from the operators of the WWTPs. The pollutant concentrations in 2019 were compared with data from the “pandemic” year—2020. The loads of catering waste entering the sewerage system in 2019 ranged from 32.7 to 1062 tons. In the town with the largest tourist base, the BOD (Biochemical Oxygen Demand) value in 2020 accounted for 62.3% of the 2019 value. In the largest town, the annual energy consumption for food waste treatment could be up to 2,539,770 kWh. If the waste was fermented, up to 1,376,650 m3 of methane could be obtained. There is a strong need to implement a collection system for food waste from catering facilities, and the fermentation of this waste to produce methane, which can be used for energy purposes.

Soilless tomato cultivation wastewater, with typically low COD, high concentrations of phosphorus, and oxidized forms of nitrogen, may be effectively treated in a rotating electrochemical disk contactor (RECDC) and in a bioelectrochemical reactor (BER), such as a rotating electrobiological disk contactor (REBDC). The aim of this study was to determine the technological parameters of both reactors, i.e., electric current density (J) and hydraulic retention time (HRT), depending on the effluent quality requirements. The study was conducted with four one-stage RECDCs and with four one-stage REBDCs, at four hydraulic retention times, i.e., 4, 8, 12, and 24 h, and electric current densities of 0.63, 1.25, 2.50, 5.00, and 10.00 A/m2. It was demonstrated that soilless tomato cultivation wastewater could be effectively treated in electrochemical and electrobiological disk contactors, and then discharged to sewage system facilities. In a RECDC, the highest denitrification (53.4%) and dephosphatation (99.8%) performance was achieved at J = 10.0 A/m2 and HRT = 24 h. If the effluents are to be discharged to natural reservoirs, their effective treatment is only feasible in a REBDC. The bioelectrochemical disk contactor ensured over 90% dephosphatation effectiveness. At HRT = 24 h and all electric current densities studied, the concentrations of pollutants in the effluent met requirements set for industrial wastewater discharged into natural waters and the ground. By applying J = 2.5 A/m2 and HRT = 24 h in the REBDC, it was possible to achieve a phosphorus concentration below 3.0 mg P/L and concentrations of ammonia nitrogen and nitrites lower than the permissible levels for treated industrial wastewater introduced to waters and to the ground. Given the nitrate concentration (exceeding 30 mg N/L), an external carbon source is recommended to aid a treatment process that uses a technological system with a REBDC. Technological schemes were proposed for wastewater treatment plants (WWTPs) with a RECDC and a REBDC, for discharging treated wastewater to natural waters, the ground, and sewage systems.

The present study aimed to determine the kinetics of pollutant removal in biofilters with LECA filling (used as a buffer to prevent de-icing agents from being released into the environment with stormwater runoff). It demonstrated a significant effect of temperature and a C/N ratio on the rate of nitrification, denitrification, and organic compound removal. The nitrification rate was the highest (0.32 mg N/L·h) at 25 °C and C/N = 0.5, whereas the lowest (0.18 mg N/L·h) at 0 °C and C/N = 2.5 and 5.0. Though denitrification rate is mainly affected by the available quantity of organic substrate, it actually decreased as the C/N increased and was positively correlated with the temperature levels. Its value was found to be the highest (0.31 mg N/L·h) at 25 °C and C/N = 0.5, and the lowest (0.18 mg N/L·h) at 0 °C and C/N = 5.0. As the C/N increased, so did the content of organic compounds in the treated effluent. The lowest organic removal rates were noted for C/N = 0.5, ranging between 11.20 and 18.42 mg COD/L·h at 0 and 25 °C, respectively. The highest rates, ranging between 27.83 and 59.43 mg COD/L·h, were recorded for C/N = 0.5 at 0 and 25 °C, respectively.