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Continuous thermophilic composting (CTC) is potentially helpful in shortening the composting cycle. However, its universal effectiveness and the microbiological mechanisms involved are unclear. Here, the physicochemical properties and bacterial community dynamics during composting of distilled grain waste in conventional and CTC models were compared. CTC accelerated the organic matter degradation rate (0.2 vs. 0.1 d -1 ) and shortened the composting cycle (24 vs. 65 d), mainly driven by the synergism of bacterial genera. Microbial analysis revealed that the abundance of Firmicutes was remarkably improved compared to that in conventional composting, and Firmicutes became the primary bacterial phylum (relative abundance >70 %) during the entire CTC process. Moreover, correlation analysis demonstrated that bacterial composition had a remarkable effect on the seed germination index. Therefore, controlling the composting process under continuous thermophilic conditions is beneficial for enhancing composting efficiency and strengthening the cooperation between bacterial genera., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The present study compared the development of various physicochemical properties and the composition of microbial communities involved in the composting process in the solid fraction of dairy manure (SFDM) with a sawdust-regulated SFDM (RDM). The changes in several primary physicochemical properties were similar in the two composting processes, and both resulted in mature end-products within 48days. The bacterial communities in both composting processes primarily comprised Proteobacteria and Bacteroidetes. Firmicutes were predominant in the thermophilic phase, whereas Chloroflexi, Planctomycetes, and Nitrospirae were more abundant in the final mature phase. Furthermore, the succession of bacteria in both groups proceeded in a similar pattern, suggesting that the effects of the bulking material on bacterial dynamics were minor. These results demonstrate the feasibility of composting using only the SFDM, reflected by the evolution of physicochemical properties and the microbial communities involved in the composting process., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Aerobic composting of distilled grain waste (DGW) at different initial pH values adjusted by CaO addition was investigated. Three pH-adjusted treatments with initial pH values of 4 (R1), 5 (R2) and 6 (R3) and a control treatment (R0) with a pH value of 3.5 were conducted simultaneously. The results showed that R0 had an unsuccessful start-up of composting. However, the pH-adjusted treatments produced remarkable results, with a relatively high initial pH being beneficial for the start-up. Within 65days of composting, the degradation of volatile solids (VS) and the physicochemical properties of R2 and R3 displayed similar tendencies, and both produced a mature end-product, while R1 exhibited a lower VS degradation rate, and some of its physicochemical properties indicated the end-product was immature. Quantitative PCR analysis of ammonia oxidizers indicated that the occurrence of nitrification during the composting of DGW could be attributed to the activity of ammonia-oxidizing bacteria., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Biogas can be produced from distilled grain waste by dry anaerobic digestion, however, digested residue was eluted and needs further treatment. To develop a zero-emission process and achieve efficient resource recovery, the compostability of the digested residue was studied. Composting of the digested residue by adding a mature compost and bulking agent was performed using a lab-scale composting reactor. The composting process showed that the degradation of organic matters was mainly occurred during the first 30 days, and the final volatile solid (VS) degradation efficiency was about 15.2%. The digested residue was not suitable as a fertilizer as revealed by the lower germination index (GI) value. However, the composting process produced remarkable results; the physico-chemical parameters indicated that a highly mature end product was obtained 65 days after beginning the composting process. The final nitrogen content, NO 3 − concentration, and GI value in the final product were 1.7%, 11,128.8 mg·kg −1 -TS, and 110.0%, respectively. A highly statically significant correlation was found among the GI, pH, soluble total organic carbon (S-TOC), inorganic carbon (IC), and concentrations of NH 4 + and NO 3 − . The numbers of ammonia oxidizing bacteria (AOB) and archaea (AOA) decreased during the first 12 days, but significant increases occurred during the maturation phase, indicating that AOB and AOA were responsible for nitrification during the composting of digested residue. [ABSTRACT FROM AUTHOR]

The present study compared the development of various physicochemical properties and the composition of microbial communities involved in the composting process in the solid fraction of dairy manure (SFDM) with a sawdust-regulated SFDM (RDM). The changes in several primary physicochemical properties were similar in the two composting processes, and both resulted in mature end-products within 48 days. The bacterial communities in both composting processes primarily comprised Proteobacteria and Bacteroidetes . Firmicutes were predominant in the thermophilic phase, whereas Chloroflexi, Planctomycetes , and Nitrospirae were more abundant in the final mature phase. Furthermore, the succession of bacteria in both groups proceeded in a similar pattern, suggesting that the effects of the bulking material on bacterial dynamics were minor. These results demonstrate the feasibility of composting using only the SFDM, reflected by the evolution of physicochemical properties and the microbial communities involved in the composting process. [ABSTRACT FROM AUTHOR]

Digested residue remained at the end of a process for the production of fuel ethanol and methane from kitchen garbage. To develop a zero-emission process, the compostability of the digested residue was assessed to obtain an added-value fertilizer. Composting of the digested residue by adding matured compost and a bulking agent was performed using a lab-scale composting reactor. The composting process showed that volatile total solid (VTS) degradation mainly occurred during the first 13 days, and the highest VTS degradation efficiency was about 27% at the end. The raw material was not suitable as a fertilizer due to its high NH 4 + and volatile fatty acids (VFAs) concentration. However, the composting process produced remarkable results; the physicochemical properties indicated that highly matured compost was obtained within 62 days of the composting process, and the final N concentration, NO 3 − concentration, and the germination index (GI) at the end of the composting process was 16.4 g kg −1 -TS, 9.7 g kg −1 -TS, and 151%, respectively. Real-time quantitative PCR ( q PCR) analysis of ammonia oxidizers indicated that the occurrence of nitrification during the composting of digested residue was attributed to the activity of ammonia-oxidizing bacteria (AOB). [ABSTRACT FROM AUTHOR]