Traditional fertilizers are highly inefficient, with a major loss of nutrients and associated pollution. Alternatively, biochar loaded with phosphorous is a sustainable fertilizer that improves soil structure, stores carbon in soils, and provides plant nutrients in the long run, yet most biochars are not optimal because mechanisms ruling biochar properties are poorly known. This issue can be solved by recent developments in machine learning and computational chemistry. Here we review phosphorus-loaded biochar with emphasis on computational chemistry, machine learning, organic acids, drawbacks of classical fertilizers, biochar production, phosphorus loading, and mechanisms of phosphorous release. Modeling techniques allow for deciphering the influence of individual variables on biochar, employing various supervised learning models tailored to different biochar types. Computational chemistry provides knowledge on factors that control phosphorus binding, e.g., the type of phosphorus compound, soil constituents, mineral surfaces, binding motifs, water, solution pH, and redox potential. Phosphorus release from biochar is controlled by coexisting anions, pH, adsorbent dosage, initial phosphorus concentration, and temperature. Pyrolysis temperatures below 600 °C enhance functional group retention, while temperatures below 450 °C increase plant-available phosphorus. Lower pH values promote phosphorus release, while higher pH values hinder it. Physical modifications, such as increasing surface area and pore volume, can maximize the adsorption capacity of phosphorus-loaded biochar. Furthermore, the type of organic acid affects phosphorus release, with low molecular weight organic acids being advantageous for soil utilization. Lastly, bioch

The energy crisis, depletion of fossil fuels, and global waste issue highlight the need for sustainable and eco-friendly energy processes. In this study, the anaerobic co-digestion of sewage sludge (DS), milk sludge (MS), and food waste (FW) with glycerol (GL) from biodiesel production was investigated. Binary co-digestion of MS-GL, DS-GL, and FW-GL, as well as ternary co-digestion of MS-FW-GL and DS-FW-GL, were examined to determine the optimal combinations for biogas production and process stability. Adding 5% GL (v/v) increased methane yields by 88.78%, 405.82%, and 40.03% for binary mixtures and 55.57% and 298.53% for ternary mixtures, respectively. In addition, the ternary mixtures resulted in the accumulation of volatile fatty acids at 2136.96 mg/L and 1843.62 mg/L, respectively, causing a reduction in methane yield compared to that in binary mixtures. GL added to binary and ternary mixtures delayed optimal methanogenic activities, with higher hydrolysis rates and shorter lag times observed in single substrate-contained and binary mixture reactors. Ternary mixtures showed lower hydrolysis rates and longer lag times, indicating that methanogens required more time to adjust to the increased organic content. Co-digestion procedures using different substrate ratios should consider the risk of organic overloads, which can lead to system instability or failure.

The study explores the essential role of Life Cycle Assessment (LCA) in assessing the environmental sustainability impacts of biochar as a green sorbent in soil remediation. Recent studies from 2021 to 2023 underscore biochar's potential for global warming mitigation and carbon sequestration. The review discusses various concerns related to biochar-to-soil LCA, including its effects on heavy metals and pesticides in soils, the necessity for additional research on application frequency for pollutant sorption, impacts on real/different soil carbon stocks, variability in biochar properties, limited long-term studies, potential health implications, and incomplete assessment of pollutant dynamics, considering different biochar production methods and soil surface albedo. Advocating for LCAs for other green sorbents, such as low-cost clay, chitosan, and green nano-sorbents, is essential. Additionally, the integration of multiple green remediation techniques is proposed to enhance overall efficiency in soil and environmental remediation practices.