Low-cost anaerobic digester to promote the circular bioeconomy in the non-centrifugal cane sugar sector: A life cycle assessment

Energy potential of elephant grass broth as biomass for biogas production

The growing demand for clean energy has highlighted plant biomass as a valuable alternative, supporting sustainable development goals. Elephant grass (EG) is a promising feedstock due to its adaptability to diverse soils and climates, high dry matter production, and substantial energy yield. This study aimed to evaluate and characterize six selected EG genotypes (BRS Capiaçu, T_23.1, T_23.2, T_41.2, T_47.1, and T_51.5) based on their broth productivity and energy yield. Analysis of the broth's yield and physicochemical properties revealed that the by-product extracted from the biomass had a high residual energy value. Additionally, extracting the broth reduces the grass's biomass moisture content, enhancing its calorific value and improving the bagasse quality for combustion in boilers, thus optimizing energy production. This study demonstrates that the promising EG genotypes T_47.1, T_41.2, and T_23.1 presented relevant energy values ranging from 4248.12 to 4304.06 kcal kg- 1 of bagasse and thus are suitable for energy production through direct combustion. The extracted broth is a valuable residual energy source that can be utilized industrially after anaerobic digestion. Future research should focus on the environmental and economic effectiveness of EG broth as an energy source from waste and its potential for biogas production.

Alternative prioritization for mitigating competition-related issues in Tanzania sugar industry using an integrated multi-criteria decision-making approach

Professionals and policymakers often encounter challenges in selecting and ranking effective solutions to address competition-related issues in various industries including sugar industry. Despite extensive research in this area, the Tanzanian context, significantly impacted by these challenges, has not received sufficient attention. Thus, this study aims to fill this gap by identifying and prioritizing these issues. It proposes four strategies and establishes five criteria for prioritization. To achieve this, the study introduces an integrated methodology to assess criteria weights and rank strategies based on these weighted criteria. The FullEX technique is applied to assess the criteria weights, while the AROMAN (Alternative Ranking Order Method Accounting for Two-Step Normalization) method is used to rank the alternatives. The study validates this methodology through a sensitivity and comparative analyses, which identifies the amendment of the law to accommodate the leniency program (S1) as the most appropriate strategy for mitigating competition-related issues in the sugar industry.

Nexus of food waste and climate change framework: Unravelling the links between impacts, projections, and emissions

This communication explores the intricate relationship between food waste and climate change, considering aspects such as impacts, projections, and emissions. It focuses on the pressing issue of waste generation and its potential consequences if current trends persist, and emphasises the importance of efficient solid waste management in improving environmental quality and fostering economic development. It also highlights the challenges faced by developing countries in waste collection and disposal, drawing comparisons with the waste utilisation methods used by developed nations. The review delves into the link between food waste and climate change, noting the paradoxical situation of food wastage against the backdrop of global hunger and malnutrition. It underscores the scientific evidence connecting food waste to climate change and its implications for food security and climate systems. Additionally, it examines the environmental burden imposed by food waste, including its contribution to greenhouse gas emissions and the depletion of resources such as energy, water, and land. Besides environmental concerns, this communication also highlights the ethical and socioeconomic dimensions of food waste, discussing its influence on Sustainable Development Goals, poverty, and social inequality. The communication concludes by advocating for collective action and the development of successful mitigation strategies, technological solutions, and policy interventions to address food waste and its climate impacts. It emphasises the need for collaboration, awareness, and informed decision-making to ensure a more sustainable and equitable future.

Investigations into valorisation of trade wastewater for biomethane production

Biogas production from wastewater is one way that industrial sites can work towards the UN Sustainable Development Goals, while recovering a valuable resource. The objective of this study was to investigate the suitability of data collected by municipal wastewater service providers as a method of classifying and screening waste producers as potential sites for biogas resource recovery by anaerobic digestion. Industrial wastewater samples, including raw effluent and treated waste ready for discharge, were examined, and biomethane potential assays performed. Results of chemical analysis and lab-scale digestion were compared to historical service provider data, and patterns were observed. Biomethane yields of up to 357 mL/gVS and 287mL/gVS were achieved from raw and treated effluent respectively. Digestion at the top four prospects could produce over 4690 GJ of methane and save $47,000 in natural gas costs, offsetting 490 tonnes of CO2 equivalent annually. These streams, from logistics, waste management, food and animal product businesses, combined high levels of degradable substrates and low levels of inhibitory components. While it is unlikely that this type of screening program can be completely accurate, certain parameters, including high sodium concentration, are applicable for discounting the potential for biogas production. This knowledge can be a valuable tool in the process of selecting sites for future resource recovery, therefore increasing the uptake of these processes, resulting in economic, environmental, and climate change mitigation benefits.

Recent advances in biogas production using Agro-Industrial Waste: A comprehensive review outlook of Techno-Economic analysis

Agrowaste sources can be utilized to produce biogas by anaerobic digestion reaction. Fossil fuels have damaged the environment, while the biogas rectifies the issues related to the environment and climate change problems. Techno-economic analysis of biogas production is followed by nutrient recycling, reducing the greenhouse gas level, biorefinery purpose, and global warming effect. In addition, biogas production is mediated by different metabolic reactions, the usage of different microorganisms, purification process, upgrading process and removal of CO₂ from the gas mixture techniques. This review focuses on pre-treatment, usage of waste, production methods and application besides summarizing recent advancements in biogas production. Economical, technical, environmental properties and factors affecting biogas production as well as the future perspective of bioenergy are highlighted in the review. Among all agro-industrial wastes, sugarcane straw produced 94% of the biogas. In the future, to overcome all the problems related to biogas production and modify the production process.

Benefits and risks of agricultural reuse of digestates from plastic tubular digesters in Colombia

The aim of this study is to characterize the digestates from three plastic tubular digesters implemented in Colombia fed with: i) cattle manure; ii) cattle manure mixed with cheese whey; iii) pig manure. All the digesters worked under psychrophilic conditions. Physico-chemical characteristics, heavy metals, pathogens, and agronomic quality were investigated. All the digestates were characterized by physico-chemical characteristics and nutrients concentration suitable for their reuse as biofertilizer. However, these digestates may only partially replace a mineral fertilizer due to the high nutrients dilution. Heavy metals were under the detection limit of the analytical method (Pb, Hg, Ni, Mo, Cd, Chromium VI) or present at low concentration (Cu, Zn, As, Se) in all the digestates. Biodegradable organic matter and pathogens (coliform, helminths and Salmonella spp.) analysis proved that all the digestates should be post-treated before soil application in order to prevent environmental and health risks, and also to reduce residual phytotoxicity effects. The digestate from pig manure had a higher nutrient percentage (0.2, 0.6 and 0.05 % w/w of total N, P₂O₅ and K₂O, respectively), but also higher residual phytotoxicity than the other digestates. Co-digestion seemed not to significantly improve the digestate fertilizing potential. Finally, further studies should address how to improve fertilizing potential of digestates from plastic tubular digesters, avoiding environmental and health risks.

Biogas Production by Pilot-Scale Anaerobic Co-Digestion and Life Cycle Assessment Using a Real Scale Scenario: Independent Parameters and Co-Substrates Influence

This study evaluates the performance of different agricultural by-products to identify the potential effect of independent variables, using as the dependent variable the biogas production. A Box–Behnken experimental design was carried out in a pilot-scale plant of four stirred stainless-steel digesters under mesophilic semi-continuous digestion. The results obtained support the creation of a technical framework to scale up the process and further evaluation of the potential environmental impacts through life cycle assessment (LCA) methodology. A stable behaviour was achieved in 12 of the 13 experiments proposed. The highest value of daily biogas production was 2200.15 mL day−1 with a stabilization time of 14 days, an organic loading rate of 4 g VS feed daily, low C/N ratio and a 1:1 relation of nitrogen providers. The concentrations of CH4 remained stable after the production stabilization and an average biogas composition of 60.6% CH4, 40.1% CO2 and 0.3% O2 was obtained for the conditions mentioned above. Therefore, the real scale plant was estimated to manage 2.67 tonnes of residual biomass per day, generating 369.69 kWh day−1 of electricity. The LCA analysis confirms that the co-digestion process evaluated is a feasible and environmentally sustainable option for the diversification of the Colombian energy matrix and the development of the agro-industrial sector.