| Abstrakt: |
Background and Objectives Composting is an effective approach for organic waste management, but it also has disadvantages such as greenhouse gases emission (CH4, CO2, and N2O), bad smells, nitrogen loss, and contamination of soil and water resources. Therefore, it is crucial to develop a method to reduce gas emissions and improve the quality of compost at the same time. To overcome these disadvantages, some additives are usually used. The use of additives at the beginning of the composting process to produce valuable compost is known as "cocomposting". Various materials can be incorporated into waste during composting. These materials fall into three categories: organic, mineral, biological, or a combination of these. Some of these added materials serve as bulking agents, primarily affecting the physical structure of the compost (such as aeration). However, most of the time, these substrates also have direct or indirect impacts on other composting factors and can be considered as additives. Additives play a role in enhancing the composting process by reducing leaching and gas emissions, improving aeration, accelerating organic matter breakdown, and enhancing nutrient content and availability in the final product. The research published so far showed that the effect of wood biochar along with leonardite and coal on the quality of compost obtained from animal manure and forest organic matter had not been studied in Iran, and considering the importance of the feasibility of improving the quality of compost, this research was conducted. Methodology In this research, the effect of wood biochar, leonardite and coal on some characteristics and quality indices of the co-compost of animal manure and forest organic matter was studied. The biochar was produced at 400° C from the pyrolysis of mixed pruning plum and pomegranate brunches. Leonardite and coal were also prepared from companies active in this field. The experiment was conducted as a factorial in a completely random basic design with three replications. The first factor of treatment included wood biochar, leonardite and coal at two levels of 2 and 4% by dry weight and the second factor of time included 12 weeks. During the composting process, temperature, pH, EC, total nitrogen concentration, organic carbon content and some quality indices of composting such as humification index (HR), humification ratio (HI), degree of polymerization (DP) and total materials Humic (HS) were measured. Findings According to the results, the treatments were significantly different from the control regarding the temperature of the compost pile, and the coal treatment showed the highest temperature at the level of 2%, and the duration of the thermophilic phase in the leonardite treatment was 2% longer than the other treatments. Among the additives, 2% and 4% leonardite treatments created the highest total nitrogen content in the compost. The additives used in this research did not make a significant difference in compost pH, but coal at the level of 4% caused a significant increase in electrical conductivity (EC). Biochar and coal increased organic carbon concentration in the compost pile. Leonardite treatments of 2% and 4% produced the highest values of humification indices (HS, DP, HI, HR), but they were not significantly different from each other. The biochar used in this research increased the C/N ratio of co-compost. Conclusion In general, leonardite treatments were found to be useful in terms of the indicators of final compost and biochar and coal treatments to accelerate composting in the early stages. But the results of this research showed that it can be used at the end of composting processes in order to enrich and improve the quality of the produced compost. The results of this research showed that considering the costs of raw materials, coal is a suitable treatment to accelerate the production and improve the quality of compost. The results obtained about the effect of biochar obviously cannot be generalized to all biochars and different results may be obtained depending on the type of biomass and pyrolysis conditions. Therefore, it is recommended to use the combination of organic and biological or organic and inorganic additives in future research. Other traits such as indices of microbial contamination and abundance of weed seeds should also be measured and the effect of treatments should be studied. Finally, it is recommended to study the effect of final compost on the characteristics of calcareous and acidic soils. [ABSTRACT FROM AUTHOR] |
