Search Results (5)

The increasing global energy demand, coupled with the urgent need to reduce CO₂ emissions, has intensified the search for renewable energy sources. Biogas, produced from agro-industrial biomass, presents a viable solution. In beer production, brewery’s spent grain (BSG), the largest by-product by volume, offers potential for bioenergy recovery. This study applied a biorefinery approach to BSG, extracting protein hydrolysates (PH) through mild alkaline hydrolysis and nanostructured lignin (LN) via the Ionic Liquid Method. The objective was to assess biogas production from the residual biorefinery biomass and evaluate the co-digestion of BSG with Olive Mill Wastewater (OMWW) and Olive Pomace (OP), by-products of the olive oil industry. Biogas was produced in lab-scale batch reactors and the quantity of biogas produced was measured via the volumetric method. Conversely, the amount of biomethane obtained was evaluated by introducing, in the production chain, an alkaline trap. Biogas yields were the highest for untreated BSG (1075.6 mL), co-digested BSG with OMWW (1130.1 mL), and BSG residue after PH extraction (814.9 mL). The concentration of biomethane obtained in the various samples ranged from 54.5 vol % (OMWW + BSG) to 76.59 vol % (BSG). An energy balance analysis considering both the theoretical energy consumed by a semi-continuous anaerobic digestion bioreactor and the energy produced as bio-CH₄ revealed that BSG after PH extraction was the most energy-efficient treatment, producing a net energy gain of 5.36 kJ. For the scope, the energy consumption was calculated by considering a PEIO index equal to 33% of the energy produced during the day, showing the highest biogas production. In contrast, the co-digested BSG with OMWW yielded the lowest net energy gain of 1.96 kJ. This comprehensive analysis highlights the energy efficiency of different treatments, identifying which process should be improved. Full article

Sewage sludge (SS) generation and its management still pose a problem in many countries. Anaerobic co-digestion (AcD) of SS with grease trap sludge (GTS) and organic fraction of municipal sewage waste (OFMSW), which are two easily biodegradable substrates, may improve biogas production and AcD kinetics. Algae biomass (AB) of the species Undaria pinnatifida can be the third co-digestion component that may also affect the AcD performance. The aim of the study was therefore to evaluate the performance of mesophilic and thermophilic SS batch AcD with OFMSW, GTS as well as AB through biochemical methane potential (BMP) assay in relation to cumulative specific biogas (Y_B) and methane yields (Y_m). Three kinetic models were applied within the scope of the kinetic study. Results of the study showed that the mixture containing SS, GTS and AB brought the most noticeable improvements in Y_m compared to other studied mixtures and in respect to standalone SS digestion, the improvement amounted to 88.37% at mesophilic temperature (260.83 ± 15.02 N mL CH₄/g-VS_add and for standalone SS 138.47 ± 4.70 N mL CH₄/g-VS_add) and 71.09%, respectively, at the thermophilic one (275.66 ± 4.11 N mL-CH₄/g-VS_add and for SS standalone 161.13 ± 13.11 N mL-CH₄/g-VS_add). Full article

A new approach of siloxane sampling based on impinger, micro-impinger, adsorption on active carbon, and direct TedlarBag methods followed by gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of three linear (L2–L4) and four cyclic (D3–D5) volatile methyl siloxanes (VMSs). Three kinds of organic liquid-medium characterized by different polarities, namely acetone, methanol, and d-decane as siloxanes trap were arranged in the experiment which is widely discussed below. Thus, the GC-MS equipped with SUPELCOWAX-10 capillary column was employed to perform monitoring of VMS content in the analyzed biogas samples originating from landfill, wastewater treatment plants, and agriculture biogas plants. In all samples that have undergone the analysis, cyclic and linear VMSs were found in quantities exceeding 107.9 and 3.8 mg/m³, respectively. Significant differences between siloxanes concentrations depending on biogas origin were observed. Moreover, the high range of linearity (0.1 to 70.06 mg/m³), low LoD (0.01 mg/m³), low LoQ (0.04 mg/m³), and high recovery (244.1%) indicate that the procedure and can be applied in sensitive analyses of silica biogas contaminants. In addition to the above, the impinger method of sampling performed better than active-carbon Tube and TedlarBag, particularly for quantifying low concentrations of siloxanes. Overall, the evaluation of sampling methods for biogas collection simplified the analytical procedure by reducing the procedural steps, avoiding the use of solvents, as well as demonstrated its applicability for the testing of biogas quality. Full article

Organic waste exploitation is crucial for waste emissions restraint in air, soil and water. This type of waste can be exploited to produce biogas, a valuable fuel exploitable for energy purposes. A circular approach for energy production is much cleaner and more sustainable than the traditional linear approach. In this work, organic waste was used for biogas production to feed a highly efficient solid oxide fuel cell power generator, which requires an ultra-purified fuel. Commercial sorbents were experimentally studied in conjunction with a dynamic adsorption model to predict the breakthrough time and organize the material change-over. In the presence of 0.1% oxygen in the gas mixture, AirDep^® CKC showed a marked increase in the adsorption capacity (from 3.91 to 84.87 mg/g), overcoming SulfaTrap^® R8G (49.91 mg/g). The effect of several operating parameters on adsorption capacity was evaluated: inlet H₂S concentration, filter geometry and gas mixture velocity. Experimental data revealed that adsorption capacity increases with initial H₂S concentration, following the typical trend of the Langmuir isotherm. Model simulations were in good agreement compared to experimental results, with an average relative error lower than 7%. A sensitivity analysis on the adsorption capacity was accomplished considering parameters from operational and empirical correlations. Full article

This paper presents the sustainability implications of installing biogas trapping systems in palm oil mills of a crude palm oil production supply chains in Malaysia. The study evaluates the impact of this mitigation strategy on the existing supply chains published by Lim and Biswas. The experience of a local palm oil mill installed with the KUBOTA biogas trapping system was incorporated into a typical 60 metric tonne per hour palm oil mill for effluent treatment. This allowed us to assess the changes in sustainability performance of the whole crude palm oil supply chain using the Palm Oil Sustainability Assessment (POSA) framework. Installing the biogas trapping system increased waste recycling and reuse percentage of the mill from 81.81% to 99.99% and the energy ratio (energy output/fossil fuel and biomass energy input) from 2.45 to 2.56; and reduced the Greenhouse Gas emission of the supply chain from 0.814 tonne CO₂eq to 0.196 tonne CO₂eq per tonne of Crude Palm Oil. This system could also potentially increase the mill’s annual revenue by 2.3%, while sacrificing the sustainability performance of other economic indicators (i.e., a further 3% negative deviation of actual growth rate from sustainable growth rate). Overall, sustainability score of the supply chain improved from 3.47/5 to 3.59/5 on the 5-level-Likert-scale due to environmental improvement strategy consideration. Finally, this paper shows that the POSA framework is capable of capturing changes in the sustainability performance of triple bottom line indicators associated with the use or incorporation of any improvement strategy in the crude palm oil supply chain. Full article