Soils and Beyond: Optimizing Sustainability Opportunities for Biochar

Fabrication of engineered biochar for remediation of toxic contaminants in soil matrices and soil valorization

Biochar has emerged as an efficacious green material for remediation of a wide spectrum of environmental pollutants. Biochar has excellent characteristics and can be used to reduce the bioavailability and leachability of emerging pollutants in soil through adsorption and other physico-chemical reactions. This paper systematically reviewed previous researches on application of biochar/engineered biochar for removal of soil contaminants, and underlying adsorption mechanism. Engineered biochar are derivatives of pristine biochar that are modified by various physico-chemical and biological procedures to improve their adsorption capacities for contaminants. This review will promote the possibility to expand the application of biochar for restoration of degraded lands in the industrial area or saline soil, and further increase the useable area. This review shows that application of biochar is a win-win strategy for recycling and utilization of waste biomass and environmental remediation. Application of biochar for remediation of contaminated soils may provide a new solution to the problem of soil pollution. However, these studies were performed mainly in a laboratory or a small scale, hence, further investigations are required to fill the research gaps and to check real-time applicability of engineered biochar on the industrial contaminated sites for its large-scale application.

Mechanisms of adsorption and functionalization of biochar for pesticides: A review

Agricultural production relies heavily on pesticides. However, factors like inefficient application, pesticide resistance, and environmental conditions reduce their effective utilization in agriculture. Subsequently, pesticides transfer into the soil, adversely affecting its physicochemical properties, microbial populations, and enzyme activities. Different pesticides interacting can lead to combined toxicity, posing risks to non-target organisms, biodiversity, and organism-environment interactions. Pesticide exposure may cause both acute and chronic effects on human health. Biochar, with its high specific surface area and porosity, offers numerous adsorption sites. Its stability, eco-friendliness, and superior adsorption capabilities render it an excellent choice. As a versatile material, biochar finds use in agriculture, environmental management, industry, energy, and medicine. Added to soil, biochar helps absorb or degrade pesticides in contaminated areas, enhancing soil microbial activity. Current research primarily focuses on biochar produced via direct pyrolysis for pesticide adsorption. Studies on functionalized biochar for this purpose are relatively scarce. This review examines biochar's pesticide absorption properties, its characteristics, formation mechanisms, environmental impact, and delves into adsorption mechanisms, functionalization methods, and their prospects and limitations.

Unlocking the potential of biochar in the remediation of soils contaminated with heavy metals for sustainable agriculture

Agricultural soils contaminated with heavy metals (HMs) impose a threat to the environmental and to human health. Amendment with biochar could be an eco-friendly and cost-effective option to decrease HMs in contaminated soil. This paper reviews the application of biochar as a soil amendment to immobilise HMs in contaminated soil. We discuss the technologies of its preparation, their specific properties, and effect on the bioavailability of HMs. Biochar stabilises HMs in contaminated soil, enhance the overall quality of the contaminated soil, and significantly reduce HM uptake by plants, making it an option in soil remediation for HM contamination. Biochar enhances the physical (e.g. bulk density, soil structure, water holding capacity), chemical (e.g. cation exchange capacity, pH, nutrient availability, ion exchange, complexes), and biological properties (e.g. microbial abundance, enzymatic activities) of contaminated soil. Biochar also enhances soil fertility, improves plant growth, and reduces the plant availability of HMs. Various field studies have shown that biochar application reduces the bioavailability of HMs from contaminated soil while increasing crop yield. The review highlights the positive effects of biochar by reducing HM bioavailability in contaminated soils. Future work is recommended to ensure that biochars offer a safe and sustainable solution to remediate soils contaminated with HMs.

Optimising water holding capacity and hydrophobicity of biochar for soil amendment - A review

Biochar is a product of the thermal treatment of biomass, and it can be used for enhancing soil health and productivity, soil carbon sequestration, absorbance of pollutants from water and soil, and promoting environmental sustainability. Extensive research has been done on applications of biochar to enhance the Water Holding Capacity (WHC) of biochar amended soil. However, a comprehensive road map of biochar optimised for enhanced WHC, and reduced hydrophobicity is not yet published. This review is the first to provide not only quantitative information on the impacts of biochar properties in WHC and hydrophobicity, but also a road map to optimise biochar for enhanced WHC when applied as a soil amendment. The review shows that straw or grass-derived biochar (at 500-600 °C) increases the WHC of soil if applied at 1 to 3 % in the soil. It is clear from the review that soil of varying texture requires different particle sizes of biochar to enhance the WHC and reduce hydrophobicity. Furthermore, the review concludes that ageing biochar for at least a year with enhanced oxidation is recommended for improving the WHC and reducing hydrophobicity compared to using biochar immediately after production. Additionally, while producing biochar a residence time of 1 to 2 h is recommended to reduce the biochar's hydrophobicity. Finally, a road map for optimising biochar is presented as a schematic that can be a resource for making decisions during biochar production for soil amendment.

Biochar for agronomy, animal farming, anaerobic digestion, composting, water treatment, soil remediation, construction, energy storage, and carbon sequestration: a review

In the context of climate change and the circular economy, biochar has recently found many applications in various sectors as a versatile and recycled material. Here, we review application of biochar-based for carbon sink, covering agronomy, animal farming, anaerobic digestion, composting, environmental remediation, construction, and energy storage. The ultimate storage reservoirs for biochar are soils, civil infrastructure, and landfills. Biochar-based fertilisers, which combine traditional fertilisers with biochar as a nutrient carrier, are promising in agronomy. The use of biochar as a feed additive for animals shows benefits in terms of animal growth, gut microbiota, reduced enteric methane production, egg yield, and endo-toxicant mitigation. Biochar enhances anaerobic digestion operations, primarily for biogas generation and upgrading, performance and sustainability, and the mitigation of inhibitory impurities. In composts, biochar controls the release of greenhouse gases and enhances microbial activity. Co-composted biochar improves soil properties and enhances crop productivity. Pristine and engineered biochar can also be employed for water and soil remediation to remove pollutants. In construction, biochar can be added to cement or asphalt, thus conferring structural and functional advantages. Incorporating biochar in biocomposites improves insulation, electromagnetic radiation protection and moisture control. Finally, synthesising biochar-based materials for energy storage applications requires additional functionalisation.

Study in Driving Strategy and Analysis of Sustainable and Symbiosis Development Relationship between Agricultural Industrial Clusters and Agricultural Logistics Industry

Due to a lack of profound disclosure of the internal mechanism for the symbiotic development of agricultural industrial clusters and agricultural logistics industry, the current study finds it difficult to form specific and implementable driving countermeasures well. Quantitative research on their symbiotic development and evolution is an important method to promote the further development of agricultural industry and agricultural logistics industry. In this paper, the factors affecting the sustainable symbiotic development relationship are analyzed between agricultural industry clusters and agricultural logistics industry with explanatory structural equation, and a system-driving model is constructed for the symbiotic development of agricultural enterprise clusters and agricultural logistics industry. The analysis indicated that, for the symbiotic development of agricultural enterprise clusters and agricultural logistics industry, the macro policy orientation is the fundamental driving force and the symbiotic development effect is its final result. Seven driving paths are refined, and the relevant countermeasures to promote the sustainable development of agricultural industrial clusters and agricultural logistics industry are put forward one at a time.

Can Bottom Sediments Be a Prospective Fertilizing Material? A Chemical Composition Analysis for Potential Reuse in Agriculture

Every year, huge amounts of bottom sediments are extracted worldwide, which need to be disposed. The recycling of bottom sediments for soil fertilization is in line with the long-promoted circular economy policy and enables the use of micro and macronutrients accumulated in sediments for soil fertilization. When considering potential agricultural reuse of the dredge sediments, the first necessary step should be to analyze whether the heavy metal content meets the obligatory criteria. Then, the contents of valuable elements required for plant growth and their ratios should be assessed. In this study, the content of nitrogen, organic carbon, phosphorus, and potassium was tested and iron, sulfur, calcium, and magnesium were also analyzed along vertical profiles of sediments extracted from four urban retention tanks in Gdańsk (Poland). The sediments were indicated to have a low content of nutrients (Ntot 0.01–0.52%, Corg 0.1–8.4%, P₂O₅ 0.00–0.65%, K 0.0–1.0%), while being quite rich in Fe and S (0.2–3.3%, 0.0–2.5%, respectively). The C/N ratio changed in the range of 17.4–28.4, which proved good nitrogen availability for plants. The mean values of the Fe/P ratio were above 2.0, which confirms that phosphorus in the sediments would be available to the plants in the form of iron phosphate. To summarize, the bottom sediments from municipal retention reservoirs are not a perfect material for soil fertilization, but they are a free waste material which, when enriched with little cost, can be a good fertilizer. Future research should focus on cultivation experiments with the use of sediments enriched with N, P, Corg.