Publications

Hydrogen sulphide (H2S) gas is typically formed in sewage collection systems that are conducive to creation of septic conditions. Collection systems in warm climates that have a flat grade or do not have the flow-through velocities (minimum two feet per second) to prevent the stagnation of fluid, allow the septic conditions to occur. In general, septic conditions occur when bacteria use all of the available oxygen while decomposing organic matter in wastewater for energy. Sewers with low velocities encourage the growth of anaerobic bacteria in a slime layer coating the sewer. These bacteria reduce sulphur compounds such as sulphate (SO4), thereby producing sulphites (SO2). These compounds occur naturally in domestic sewage but also can be concentrated in industrial waste streams. One of the more frustrating problems of H2S development from domestic and industrial wastewaters in collection systems is odours. Odour problems often are resolved by chemical addition. Chlorine compounds such as bleach, sodium hypochlorite, calcium hypochlorite and ferric chloride are examples of chemicals that are effective in controlling H2S in wastewater collection systems. The aim of the study was to determine the possibility of the application of advanced oxidation process with Fenton’s reagent to the reduction of nuisance of H2S generated at putrefaction of municipal sewage. The experiment was performed at the laboratory scale. Carbon compounds transformations were observed, redox potential, H2S concentration in biogas, and rate of purification were determined. Investigations were conducted in five phases, on laboratory-scale experimental anaerobic reactor at the temperature of 20oC. The research phases varied with the type of chemical reagents supplied to the technological system. Depending on the experimental phase different substances were dosed to the analysed sewage. Ions of Fe2+, Fe3+, H2O2, and advanced oxidation systems Fe/H2O2 and Fe/H2O2 were used in the experiment. Experimental system revealed the significance of coagulation, oxidation and advanced oxidation on deodorization of tested wastewater. Technology of reduction of H2S nuisance, generated at putrefaction of municipal sewage, based on advanced oxidation, allowed to obtain effective final results in relation to all analysed parameters.The most effective reduction of odours nuisance was obtained with classic Fenton reaction. An increase of the efficiency correlated with the increase of oxidant H2O2 doses. The dosage of 0.1 g Fe2+/dm3 and 2 g H2O2 caused sewage putrefaction after 11 days. Sewage putrefaction in control sample was observed after 24 hours. Application of advanced oxidation process was more effective method than other methods tested in the experiment. The final results of sewage preparation were far better than results observed at hydrogen peroxide, Fe2+ or Fe3+ ions application alone. Presented method of odours reduction for the sake of the obtained results, easy operation, chemical reagents accessibility and economical reasons can become alternative technology of reduction of nuisance of H2S generated at putrefaction of municipal wastewater.

Food waste (FW) to value-added application represents a demanding opportunity in the circular economy. As one of the approaches, FW hydrothermal carbonization (HTC) delivers an aqueous phase (HTC-AP), which would be suitable when applied to microbial growth and lipid production. In this context, this current work explored HTC-AP from FW obtained through hydrothermal carbonization (temperatures 200 to 260˚C) for microbial growth of 14 different Yarrowia species. Among these strains, Y. lipolytica, Y. keelungensis, Y. porcina, and Y. galii showed the ability to utilize HTC-AP. In HTC from 200˚C high optical density (OD600) reaching above 1.2 for the 4 species was observed. An increase in the temperature by 20˚C declined the growth of Y. lipolytica, Y. porcina, and Y. galii by 17%. However, Y. keelungensis showed good growth regardless of the HTC temperature. Further, the lipid produced better at higher biomass 240˚C compared to 260˚C during the HTC. Further, Y. yakushimensis showed the highest growth rate among all the analyzed media (0.12 – for medium 2 (0.45 NH4+ and 200˚C). Although the composition of HTC-AP is very diverse and often toxic, some analyzed yeast species can use the contained compounds as a carbon source for biomass and lipid biosynthesis. The presented possibilities are a very good starting point for developing processes on a larger scale.

Abstract The influence of sewage sludge torrefaction temperature on fuel properties was investigated. Non-lignocellulosic waste thermal treatment experiment was conducted within 1 h residence time, under the following temperatures: 200, 220, 240, 260, 280 and 300°C. Sawdust was used as lignocellulosic reference material. The following parameters of biochar have been measured: moisture, higher heating value, ash content, volatile compounds and sulfur content. Sawdust biochar has been confirmed to be a good quality solid fuel. High ash and sulfur content may be an obstacle for biochar energy reuse. The best temperature profile for sawdust torrefaction and fuel production for 1 h residence time was 220°C. At this temperature the product contained 84% of initial energy while decreased the mass by 25%. The best temperature profile for sewage sludge was 240°C. The energy residue was 91% and the mass residue was 85%. Higher temperatures in both cases caused excessive mass and energy losses.

Landfill leachate (LLCH) disposal poses challenges due to high pollutant concentrations. This study investigates the use of biochar (BC) derived from wheat straw for nitrogen content reduction. Laboratory experiments evaluated BC's adsorption capacity (qm) for nitrogen removal from ammonium chloride solution (NH4Cl) and LLCH, along with testing isotherm models. The results demonstrated that BC was more efficient (95.08%) than commercial activated carbon AC (93.11%), the blank, in adsorbing nitrogen from NH4Cl. This superior performance of BC may be attributed to its higher carbon content (57.74%) observed through elemental analysis. Lower results for BC/LLCH may be due to LLCH's complex chemical matrix. The Langmuir isotherm model best described BC/NH4Cl adsorption (qm = 0.5738 mg/g). The AC/NH4Cl data also fitted into the Langmuir (R2 ˃ 0.9) with a qm of 0.9469 mg/g, and 26.667 mg/g (R2 ˂ 0.9) was obtained for BC/LLCH; the BC/LLCH also gave higher qm (R2 ˃ 0.9) using the Jovanovich model (which also follows Langmuir's assumptions). The mean energy of the adsorption values estimated for the AC/NH4Cl, BC/NH4Cl, and BC/LLCH processes were 353.55, 353.55, and 223.61 kJ/mol, respectively, suggesting that they are all chemisorption processes and ion exchange influenced their adsorption processes. The Freundlich constant (1/n) value suggests average adsorption for BC/LLCH. The BC/LLCH data followed the Harkins-Jura model (R2: 0.9992), suggesting multilayered adsorption (or mesopore filling). In conclusion, biochar derived from wheat straw shows promising potential for landfill leachate remediation, offering efficient nitrogen removal capabilities and demonstrating compatibility with various adsorption models. This research also lays the groundwork for further exploration of other biochar-based materials in addressing environmental challenges associated with landfill leachate contamination.

This paper provides a comprehensive description of the new approach to biomass torrefaction under high-pressure conditions. A new type of laboratory-scale high-pressure reactor was designed and built. The aim of the study was to compare the high-pressure torrefaction with conventional near atmospheric pressure torrefaction. Specifically, we investigated the torrefaction process influence on the fuel properties of wooden-pellet for two different pressure regimes up to 15 bar. All torrefaction processes were conducted at 300 °C, at 30 min of residence time. The initial analysis of the increased pressure impact on the torrefaction parameters: mass yields, energy densification ratio, energy yield, process energy consumption, the proximate analysis, high heating value, and energy needed to grind torrefied pellets was completed. The results show that high-pressure torrefaction needed up to six percent less energy, whereas energy densification in the pellet was ~12% higher compared to conventional torrefaction. The presence of pressure during torrefaction did not have an impact on the energy required for pellet grinding (p < 0.05).

Carbon monoxide (CO) is ubiquitous in the environment. In this literature review, the biological CO transformations in ecosystems were summarized as an inspiration for the biorefinery industry. Specifically, for the first time, information about CO fate in soil, water, and the atmosphere was collected, and CO impact on plants, animals, and humans was discussed. The review also addresses the need to develop new solutions to implementing circular bioeconomy and highlights the potential of CO use in biologically mediated processes as an untapped valuable resource. Specific key areas of research were identified as 1) development of water-gas shift (WGS) bioreaction, 2) electricity production during bioelectrochemical syngas conversion (BESs), and 3) electro-fermentation (EF) as a source of added-value biochemicals and fuels.

This study aimed to evaluate the effect of replacing chalk with fly ash in a two-component polyurethane (2C PU) adhesive on its physicochemical, mechanical, and environmental properties, as a practical application of circular economy principles. Six adhesive formulations were prepared, each containing a chalk-to-fly ash ratio as a filler. The study evaluated rheological, mechanical, thermal, and environmental parameters. Mechanical tests confirmed cohesive failure within the bonded material, indicating that the bond strength at the adhesive–substrate interface exceeded the internal strength of the substrate. The highest contaminant elution levels recorded were 0.62 mg/kg for molybdenum and 0.20 mg/kg for selenium, which represent only 6.2% and 40% of the regulatory limits, respectively. Dissolved organic carbon (DOC) and total dissolved solids (TDS) did not exceed 340 mg/kg and 4260 mg/kg, respectively. GC-MS analysis did not reveal the presence of prominent volatile organic compound emissions. Initial screening suggests possible compatibility with low-emission certification schemes (e.g., A+, AgBB, EMICODE®), though confirmation requires further quantitative testing. The results demonstrate that fly ash can be an effective substitute for chalk in polyurethane adhesives, ensuring environmental compliance and maintaining functional performance while supporting the principles of the circular economy.

Hydrothermal carbonization (HTC) efficiently converts food waste into hydrochar for energy, soil improvement, and environmental remediation. However, optimizing HTC is challenging due to the complex interactions of temperature, residence time, moisture content, and catalyst dosage. This study explores the application of machine learning (ML) techniques for predicting and optimizing hydrochar yield and properties from the HTC of food waste. Key process parameters-temperature (120-360 °C), catalyst dosage (0-2 g), residence time (30-270 min), and moisture content were analyzed using three ML models: XGBoost (XGB), Support Vector Regression (SVR), and Linear Regression (LR). Among them, XGBoost demonstrated the highest predictive accuracy (R² = 0.87, MAE = 0.81, RMSE = 1.02), outperforming SVR (R² = 0.9386, MAE = 3.08) and LR (R² = 0.85, MAE = 0.86). Temperature was identified as the most significant factor (importance score = 0.91), followed by catalyst dosage (0.61). Optimized conditions yielded 48.5 g of hydrochar per 100 g of dry food waste, with an energy recovery efficiency of 68 %. The inclusion of TiO₂ nanoparticles as a catalyst significantly enhanced hydrochar properties, increasing carbon retention from 56.8 % to 77.6 %, bulk density from 0.37 g/cm³ to 0.89 g/cm³, and high heating value from 18.4 MJ/kg to 22.7 MJ/kg. These findings demonstrate the potential of ML-driven optimization for real-time control of HTC, reducing reliance on trial-and-error experimentation and advancing sustainable waste-to-energy conversion technologies.

The aim of this study was to analyze in vitro biological activities as anti-oxidant, anti-α-amylase, anti-α-glucosidase, anti-lipase, and anti-lipoxygenase activity, relative to bioactive components (phenolic acids, flavonols, xanthophylls, carotenes, esterified carotenoids, tocopherols, tocotrienols, and fatty acids) and the basic chemical composition (sugars, organic acid, dry matter, soluble solid, pH, titratable acidity, ash, pectins, and vitamin C) of Hippophaë rhamnoides berries. Six sea buckthorn cultivars commonly grown in Poland were analyzed including Aromatnaja, Botaniczeskaja-Lubitelskaja, Józef, Luczistaja, Moskwiczka, and Podarok Sadu. Berries contained 1.34–2.87 g of sugars and 0.96–4.22 g of organic acids in 100 g fresh weight, 468.60–901.11 mg of phenolic compounds, and 46.61–508.57 mg of carotenoids in 100 g dry mass. The fatty acid profile was established: palmitic > palmitoleic > oleic and linoleic > stearic and linolenic acids. The highest anti-oxidant (34.68 mmol Trolox/100 g dry mass) and anti-α-amylase potential (IC50 = 26.83 mg/mL) was determined in Aromatnaja, anti-α-glucosidase in Botaniczeskaja-Lubitelskaja (IC50 = 41.78 mg/mL), anti-lipase in Moskwiczka and Aromatnaja (average IC50 = 4.37 mg/mL), and anti-lipoxygenase in Aromatnaja and Podarok Sadu fruits (100% inhibition). The studied sea buckthorn berries may be a raw material for the development of functional foods and nutraceutical products rich in compounds with high biological activity.

ABSTRACT: The influence of light weight aggregate made of fly ash from sewage sludge thermal treatment (FASSTT LWA) on ammonia nitrogen metabolism, and on quantitative and qualitative changes of microorganisms colonizing the filling, was investigated. Two reactors were used in the experiment. The first was filled with gravel, the other with FASSTT LWA. The reactors were operated with a wastewater hydraulic loading rate of 5 mm 3 mm −2 d −1 . During the eleven‐week experiment, high efficiency of ammonia removal was observed. The lower concentrations of nitrites and nitrates in the effluent indicate that ammonia nitrogen removal resulted not just from nitrification. Nitrate concentration increase was reflected in a decrease in nitrogen removal efficiency. One possible explanation for this phenomenon is that in the period when ammonia nitrogen and nitrites were present in the reactor's FASSTT LWA filling, facilitating conditions occurred for the deammonification process.