Study on effect of Fe2+, Ni2+ and complexes on biomethane from coal and its kinetic mechanism

The process and results of anaerobic fermentation of methane production are closely related to the existence of trace elements and complexes, in order to study the influence of Fe2+, Ni2+ and complexes on the production of coal-based biomethane and the changes of parameters in the process of gas production, using the method of comparison amplification experiments, the low-rank coal in Yima coal mine was taken as the research object, and the mine drainage was used as the strain source. Four different schemes were set up to record their gas production data and COD value respectively, and the improved Gompertz model was used to simulate the methane production and degradation process of each experimental scheme.The test results show that the addition of 15 mg/L of Fe2+ and 0.005 mg/L of Ni2+ in the comparative testhas a promoting effecton biomethane production, which is beneficial to increaseoutput of coal bio-methane production as well as the degradation of organic matter.On the basis of the above experiment,the addition of 5 mg/L of EDTA can better promote the gas production and make the substrate degradation rate higher, the gas production effect and substrate degradation rate of the scale-up test are better than those of the sample test; the improved Gompertz model for the experimental scheme of methanogenesis and degradation process of the simulation results show that Fe2+ and Ni2+ and EDTA are with small sample test, its methane production potential (24.344 59 mL/g), and the maximum methane production rate (0.765 24 mL/(g·d)), the substrate degradation rate (4 535 mg/L) and the maximum substrate degradation rate (197.8 mg/(L·d))and other parameters are optimal, and the above parameters of the scale-up test should be excellent for sample test. The corresponding kinetic equations of each experimental scheme were established and tested by mathematical statistics method. The results show that the established regression equations were reliable and highly significant. The experiment and its kinetics study are helpful to understand the influence of trace elements and complexes on coal-to-biomethane, and to have a further understanding of the changes of various parameters in the process of gas production, providing a certain experimental basis for the engineering of coal-to-biomethane.