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Background: Following an extensive examination of various biofiltration packing materials within a typical bioreactor (a biofilter) is aiming to remove hydrogen sulfide (H2S) in the raw biogas. Methods: Both biochar (pre- and post-pyrolysis at 400, 500, and 600 °C) and cellular concrete (CLC) waste, representing organic and inorganic packing materials, respectively, displayed remarkable removal efficiency (RE) performance under dynamic conditions. Nevertheless, the physical and chemical properties of these packing materials play a crucial role in absorbing and trapping H2S for further filtration from the raw biogas. Key evaluations encompass chemical compositions, porosity, and specific surface area, aligning with contemporary research methodologies (e.g., XRF, Walkley-black, Kjeldahl, BET, T-plot), as analyzed in this study. Results: Subsequently, the modification of these physicochemical properties aimed to demonstrate continued interactions of iron (III) oxide (Fe2O3) with H2S for chemical modification of CLC waste, and enhance the specific surface area of biochar from 12, 22, and 24 m2/g to 235, 433, 475 m2/g, and for porosity from 0.01, 0.42, and 0.025 cm3/g to 0.096, 4, 0.24 cm3/g, respectively, for physical modification of biochar samples after pyrolysis at 400, 500, and 600 °C. Conclusion: In the end, improving the possibility of getting better RE from a laboratory-scale biofilter is possible by modification of the most effective physical (adding KOH to biochar and increasing porosity by 9 times, specific surface area by 19 times) and chemical (adding Fe2O3 to CLC waste) properties of the environment-friendly packing materials.

The increasing global demand for renewable energy sources has led to interest in generating biogas from aquatic plant biomass. This research examines the pretreatment methods of biomass, aiming to enhance the efficiency of biogas production processes. The analysis presents mechanical, chemical, biological, or combined pretreatment techniques, assessing their respective advantages, limitations, and potential synergies. The review extends beyond individual methodologies to identify potential synergies or sequential applications that could maximize biogas production efficiency. This study ultimately facilitates moving the field forward, contributes to the transition to more sustainable energy solutions, identifies gaps in existing researches, paving the way for future investigations and combat to solve upcoming energy problems. Article in English. Vandens augalų biomasės pirminio apdorojimo biodujų gamybai metodų apžvalga Santrauka Pasaulyje didėjanti atsinaujinančių energijos išteklių paklausa paskatino susidomėjimą biodujų gamyba iš vandens augalų biomasės. Šiame darbe nagrinėjami biomasės pirminio apdorojimo metodai, kuriais siekiama padidinti biodujų gamybos procesų efektyvumą. Analizėje pateikiami mechaniniai, cheminiai, biologiniai arba kombinuoti pirminio apdorojimo būdai, įvertinami atitinkami jų pranašumai, trūkumai ir galima sinergija. Darbas apima atskirų metodų apžvalgą, kad būtų galima nustatyti galimas sinergijas arba nuoseklius pritaikymus, kurie galėtų padidinti biodujų gamybos efektyvumą. Šis darbas prisideda prie energijos gamybos sektoriaus pažangos ir tvaresnių energijos sprendimų, išryškina esamų taikymo metodų spragas bei atveria kelią sprendžiant būsimas energetikos problemas. Reikšminiai žodžiai: anaerobinis skaidymas, biodujos, mikrodumbliai, pirminis apdorojimas, vandens biomasė, bioreaktorius.

The use of microalgae as a raw material for biogas production is promising. Macroalgae were mixed with cattle manure, wheat straw, and an inoculant from sewage sludge. Mixing macroalgae with co-substrates increased biogas and methane yield. The research was carried out using a three-stage bioreactor. During biogas production, the dynamics of the composition of the microbiota in the anaerobic chamber of the bioreactor was evaluated. The microbiota composition at different organic load rates (OLRs) of the bioreactor was evaluated. This study also demonstrated that in a three-stage bioreactor, a higher yield of methane in biogas was obtained compared to a single-stage bioreactor. It was found that the most active functional pathway of methane biosynthesis is PWY-6969, which proceeds via the TCA cycle V (2-oxoglutarate synthase). Microbiota composition and methane yield depended on added volatile solids (VSadded). During the research, it was found that after reducing the ORL from 2.44 to 1.09 kg VS/d, the methane yield increased from 175.2 L CH4/kg VSadded to 323.5 L CH4/kg VSadded.