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Luo C, Li S, Ren P, Yan F, Wang L, Guo B, Zhao Y, Yang Y, Sun J, Gao P, Ji P. Enhancing the carbon content of coal gangue for composting through sludge amendment: A feasibility study. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 348:123439. [PMID: 38325505 DOI: 10.1016/j.envpol.2024.123439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/03/2024] [Accepted: 01/22/2024] [Indexed: 02/09/2024]
Abstract
Cocomposting coal gangue and sludge eliminates the challenge of utilizing coal gangue. However, there is limited understanding about the feasibility of cocomposting sludge and coal gangue, as well as the composting indicators, functional microorganisms, and safety risks involved. Therefore, this study evaluated the feasibility of enhancing carbon composting in coal gangue by incorporating sludge along with sawdust as a conditioner. Three laboratory-scale reactors were designed and labeled as T1 (20 % coal gangue, 60 % sludge, and 20 % sawdust), T2 (40 % coal gangue, 40 % sludge, and 20 % sawdust), and T3 (60 % coal gangue, 20 % sludge, and 20 % sawdust). Seed germination and plant growth assessments were conducted to ensure compost stability and assess phytotoxicity to cabbage (Brassica rapa chinensis L.) in terms of growth and biomass. The results indicated that the temperature, pH, EC and ammonia nitrogen of all three reactor conditions met the requirements for product decomposition. Composting was successfully achieved when the sludge proportion was 20 % (T3). However, when the sludge proportion was markedly high (T1), the harmlessness of the compost was reduced. The germination indices of T1, T2, and T3 reached 95 %, 122 %, and 119 % at maturity, respectively. This confirmed that the harmless cycle, which involved promoting condensation and aromatization, enhancing decay, and reducing composting time, was shorter in T2 and T3 than in T1. Coal gangue can also serve as a beneficial habitat for microorganisms, promoting an increase in their population and activity. Potting experiments in sandy soil revealed that the mechanism of action of compost products in soil included not only the enhancement of soil nutrients but also the improvement of soil texture. The results of this study suggest that using coal gangue as a raw material for composting is an efficient and environmentally friendly approach for producing organic fertilizers.
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Affiliation(s)
- Chi Luo
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Shaohua Li
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Pengyu Ren
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Fan Yan
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Lu Wang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Bin Guo
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Yimo Zhao
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Yue Yang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jian Sun
- Institute of Agricultural Quality Standard and Testing Technology, Jilin Academy of Agricultural Sciences, Changchun, China
| | - Pengcheng Gao
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Puhui Ji
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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Zhai W, Li X, Duan X, Gou C, Wang L, Gao Y. Development of a microbial protease for composting swine carcasses, optimization of its production and elucidation of its catalytic hydrolysis mechanism. BMC Biotechnol 2022; 22:36. [PMID: 36443757 PMCID: PMC9703648 DOI: 10.1186/s12896-022-00768-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 11/17/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Dead swine carcass composting is an excellent method for harmless treatment and resource utilization of swine carcass. However, poor biodegradation ability of traditional composting results in poor harmless treatment effect. Researches report that the biodegradation ability of composting can be improved by inoculation with enzyme-producing microorganisms or by inoculation with enzyme preparations. At present, the researches on improving the efficiency of dead swine carcass composting by inoculating enzyme-producing microorganisms have been reported. However, no work has been reported on the development of enzyme preparations for dead swine carcass composting. METHODOLOGY The protease-producing strain was isolated by casein medium, and was identified by 16 S rRNA gene sequencing. The optimal fermentation conditions for maximum protease production were gradually optimized by single factor test. The extracellular protease was purified by ammonium sulfate precipitation and Sephadex G-75 gel exclusion chromatography. The potential for composting applications of the purified protease was evaluated by characterization of its biochemical properties. And based on amino acid sequence analysis, molecular docking and inhibition test, the catalytic hydrolysis mechanism of the purified protease was elucidated. RESULTS In this study, a microbial protease was developed for swine carcass composting. A protease-producing strain DB1 was isolated from swine carcass compositing and identified as Serratia marcescen. Optimum fermentation conditions for maximum protease production were 5 g/L glucose, 5 g/L urea, 1.5 mmol/L Mg2+, initial pH-value 8, inoculation amount 5%, incubation temperature 30 °C and 60 h of fermentation time. The specific activity of purified protease reached 1982.77 U/mg, and molecular weight of the purified protease was 110 kDa. Optimum pH and temperature of the purified protease were 8 and 50 °C, respectively, and it had good stability at high temperature and in alkaline environments. The purified protease was a Ser/Glu/Asp triad serine protease which catalyzed substrate hydrolysis by Glu, Arg, Ser, Asp and Tyr active residues. CONCLUSIONS In general, the microbial protease developed in this study was suitable for industrial production and has the potential to enhance composting at thermophilic stage. Moreover, the catalytic hydrolysis mechanism of the protease was further analyzed in this study.
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Affiliation(s)
- Wei Zhai
- grid.464353.30000 0000 9888 756XCollege of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 Jilin Province China
| | - Xintian Li
- grid.464353.30000 0000 9888 756XCollege of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 Jilin Province China
| | - Xinran Duan
- grid.464353.30000 0000 9888 756XCollege of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 Jilin Province China
| | - Changlong Gou
- grid.411647.10000 0000 8547 6673College of Animal Science and Technology, Inner Mongolia University for Nationalities, Tongliao, 028000 Inner Mongolia China
| | - Lixia Wang
- grid.9227.e0000000119573309Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102 Jilin Province China
| | - Yunhang Gao
- grid.464353.30000 0000 9888 756XCollege of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118 Jilin Province China
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