Research progress on influencing factors on compost maturity and cyanobacteria toxin degradation during aerobic cyanobacteria composting: a review

A comprehensive review on agricultural waste utilization through sustainable conversion techniques, with a focus on the additives effect on the fate of phosphorus and toxic elements during composting process

The increasing trend of using agricultural wastes follows the concept of "waste to wealth" and is closely related to the themes of sustainable development goals (SDGs). Carbon-neutral technologies for waste management have not been critically reviewed yet. This paper reviews the technological trend of agricultural waste utilization, including composting, thermal conversion, and anaerobic digestion. Specifically, the effects of exogenous additives on the contents, fractionation, and fate of phosphorus (P) and potentially toxic elements (PTEs) during the composting process have been comprehensively reviewed in this article. The composting process can transform biomass-P and additive-born P into plant available forms. PTEs can be passivated during the composting process. Biochar can accelerate the passivation of PTEs in the composting process through different physiochemical interactions such as surface adsorption, precipitation, and cation exchange reactions. The addition of exogenous calcium, magnesium and phosphate in the compost can reduce the mobility of PTEs such as copper, cadmium, and zinc. Based on critical analysis, this paper recommends an eco-innovative perspective for the improvement and practical application of composting technology for the utilization of agricultural biowastes to meet the circular economy approach and achieve the SDGs.

Electric Heating Promotes Sludge Composting Process: Optimization of Heating Method through Machine Learning Algorithms

Composting with electric heating has attracted extensive attention for the advantage of high treatment efficiency for sludge. However, there are challenges in investigating how electric heating affects the composting process and how to reduce its energy consumption. This study investigated the effects of different electric heating methods on composting. The highest temperature, water content reduction, organic matter reduction, and weight reduction rate in group B6 (heating in the first and second stages) were 76.00 ° C, 16.76 %, 4.90 %, and 35.45 %, respectively, indicating that electric heating promoted water evaporation and organic matter degradation. In conclusion, electric heating promoted the sludge composting process and the heating method of group B6 was optimal for composting characteristics. This work contributes to the understanding of the mechanism of electric heating promoting composting process and providing theoretical support for the engineering application of composting with electric heating.

Optimization of composting methods for efficient use of cassava waste, using microbial degradation

With the recent revolution in the green economy, agricultural solid waste resource utilization has become an important project. A small-scale laboratory orthogonal experiment was set up to investigate the effects of C/N ratio, initial moisture content and fill ratio (v_{cassava residue}: v_gravel) on the maturity of cassava residue compost by adding Bacillus subtilis and Azotobacter chroococcum. The highest temperature in the thermophilic phase of the low C/N ratio treatment is significantly lower than the medium and high C/N ratios. The C/N ratio and moisture content have a significant impact on the results of cassava residue composting, while the filling ratio only has a significant impact on the pH value and phosphorus content. Based on comprehensive analysis, the recommended process parameters for pure cassava residue composting are a C/N ratio of 25, an initial moisture content of 60%, and a filling ratio of 5. Under these conditions, the high-temperature conditions can be reached and maintained quickly, the organic matter has been degraded by 36.1%, the pH value has dropped to 7.36, the E4/E6 ratio is 1.61, the conductivity value has dropped to 2.52 mS/cm, and the final germination index increased to 88%. The thermogravimetry, scanning electron microscope, and energy spectrum analysis also showed that the cassava residue was effectively biodegraded. Cassava residue composting with this process parameter has great reference significance for the actual production and application of agriculture.