Biochar as a negative emission technology: A synthesis of field research on greenhouse gas emissions

Methane oxidation coupling with heavy metal and microplastic transformations for biochar-mediated landfill cover soil

The impact of co-occurring heavy metal (HM) and microplastic (MP) pollution on methane (CH4) oxidation by methanotrophs (MOB) in landfill cover soil (LCS) and the role of biochar in mediating these collaborative transformations remains unclear. This study conducted batch-scale experiments using LCS treated with individual or combined HMs and MPs, with or without biochar amendment. Differentiation in methanotrophic activities, HM transformations, MP aging, soil properties, microbial communities, and functional genes across the groups were analyzed. Biochar proved essential in sustaining efficient CH4 oxidation under HM and MP stress, mainly by diversifying MOB, and enhancing polysaccharide secretion to mitigate environmental stress. While low levels of HMs slightly inhibited CH4 oxidation, high HM concentration enhanced methanotrophic activities by promoting electron transfer process. MPs consistently stimulated CH4 oxidation, exerting a stronger influence than HMs. Notably, the simultaneous presence of low levels of HMs and MPs synergistically boosted CH4 oxidation, linked to distinct microbial evolution and adaptation. Methanotrophic activities were demonstrated to affect the fate of HMs and MPs. Complete passivation of Cu was readily achieved, whereas Zn stabilization was negatively influenced by biochar and MPs. The aging of MPs was also partially suppressed by biochar and HM adsorption.

Evaluation of the efficacy of amendment types and rates in reducing ammonia emissions from broiler litter

Several amendments have been used to reduce ammonia (NH3) emissions from broiler litter (BL); however, a comparative study between amendments and their application rates has not been fully explored. This study evaluated the potential of biochar (B), zeolite (Z), Flue Gas Desulphurization-Gypsum (FGD-G), and sodium bisulfate (S) at four application rates in reducing NH3 emissions from BL. The treatments comprised of amendment types (4) and their application rates (4), and a control with no amendment for a total of 17 treatments replicated twice and arranged in a completely randomized design. The treatments were incubated at 30 °C for 40 days at a moisture content of 40% (w/w), and NH3 emissions were measured every day for the first 10 days and 3 days intervals afterward for 40 days. Results showed that the application of 13 and 17% B (w/w) reduced cumulative NH3 emissions by 41 and 46%, respectively, compared to control over a 40-day period. Zeolite application at 8 and 11% reduced NH3 by 20 and 33%, respectively. There was no significant difference between the different rates of FGD-G, and they were generally less effective; however, a 15% FGD-G rate reduced NH3 by 9.1%. Application of S at rates of 2, 4, 6, and 7% significantly reduced NH3 emissions by 91, 99, 100, and 100 %, respectively. The effectiveness of amendments to reduce ammonia emissions followed the order: S > B > Z > FGD-G. These findings contribute to an ongoing effort to identify non-acidic amendments to minimize NH3 emissions in broiler houses.

Valorization of Manihot esculenta peel from environmental pollutant to sustainable engineering solutions for a cleaner future

As efforts intensify to address the environmental impact of agricultural waste, the valorization of Manihot esculenta peel (MEP) for sustainable engineering applications presents a unique opportunity to repurpose this class of agricultural waste to achieve environmental sustainability development goals while promoting socio-economic development of this pollutant. The inherent properties of MEP, such as its richness in carbohydrates and cellulose, make it a useful raw material for producing biofuels, bioethanols, biocomposites, and other sustainable engineering materials. Its resilience to adverse environmental conditions also makes MEP well-suited for cultivation in diverse agroecological settings, further enhancing its appeal as a sustainable resource. While existing review articles provide valuable insights into Manihot esculenta peel utilization across various industries, they often overlook the comprehensive valorization of Manihot esculenta for sustainable engineering applications, creating a notable knowledge gap. Through a systematic examination of innovative approaches documented in the literature, this research seeks to bridge this gap by elucidating strategies for repurposing cassava waste into valuable engineering materials to mitigate environmental pollution and promote sustainable resource utilization. By synthesizing existing research and identifying key research gaps, this study advances the understanding of Manihot esculenta peel's potential as a sustainable material and facilitates the transition toward greener engineering practices.

Life cycle assessment of biochar for sustainable agricultural application: A review

Biochar application is an effective strategy to address Agro-climatic challenges. However, the agro-environmental impacts of different biochar technology models are lacking of systematic summaries and reviews. Therefore, this paper comprehensively reviews recent developments derived from published literature, delving into the economic implications and environmental benefits of three distinct process namely technologies-pyrolysis, gasification, and hydrothermal carbonization. This paper specifically focuses on the agricultural life cycle assessment (LCA) methodology, and the influence of biochar preparation technologies and products on energy consumption and agricultural carbon emissions. LCA analysis shows that process and feedstock pose a predominant role on the properties and production rate of biochar, while gasification technology exhibits excellent economic attributes compared to the other two technologies. Biochar applications in agricultural has the beneficial effect of sequestering carbon and reducing emissions, especially in the area of mitigating the carbon footprint of farmland. However, the complexity of the composition of the prepared feedstock and the mismatch between the biochar properties and the application scenarios are considered as potential sources of risks. Notably, mechanism of carbon sequestration and emission reduction by soil microorganisms and agro-environmental sequestration by biochar application remains unclear, calling for in-depth studies. We review novel aspects that have not been covered by previous reviews by comparing the technical, economic, and environmental benefits of pyrolysis, gasification, and hydrothermal carbonization systematically. Overall, this study will provide a valuable framework to environmental implications of biochar preparation, application, and life cycle assessments.

Lignocellulosic biomass fertilizers: Production, characterization, and agri-applications

The growing focus on sustainable agriculture and optimal resource utilization has spurred investigations into lignocellulosic biomass as a potential source for producing environmentally friendly fertilizers. This paper reviews recent advancements in the production and application of innovative fertilizers derived from lignocellulose. It highlights potential in enhancing agricultural productivity and reducing environmental impacts such as carbon footprint and water pollution. The paper outlines various methods for conversion, highlighting the unique advantages of chemical, enzymatic, and microbiological processes, for converting lignocellulosic biomass into nutrient-rich fertilizers. The study compares the efficacy of lignocellulosic fertilizers to traditional fertilizers in promoting crop growth, enhancing soil health, and reducing nutrient losses. The results demonstrate the potential of lignocellulosic biomass-derived fertilizers in promoting resource efficiency and sustainable agriculture. While this research significantly contributes to the existing body of knowledge, further studies on long-term impacts and scalability are recommended for the development of innovative and sustainable agricultural practices.