| Using wood vinegar as a mediating additive,the initial wood vinegar was diluted 5times（A5）,50 times（A50）and 100 times（A100）respectively,and then added to the AD system of swine manure to study the effects of different concentrations of wood vinegar on the gas production characteristics,feed-liquid characteristics,biodegradability and microbial community of swine manure AD,and to explore the response relationship among wood vinegar concentration,AD characteristics and microbial community,and reveal the effects of wood vinegar on swine manure AD and its microbiological mechanism,so as to provide data reference for the improvement of anaerobic digestion of nitrogen-rich raw materials.The main research contents and conclusions are as follows:The effect of wood vinegar on the gas production characteristics of swine manure AD was studied:The gas production effect was A50>A100>Control>A5.Among them,A50 has the best gas-producing capacity,its cumulative biogas yield and cumulative methane yield are 591.05±11.39 mL g-1VS and 353.33±8.03 mL g-1VS,respectively.Its average methane content（52.72±0.70%）and the maximum methane content（72.92±0.05%）were also the highest.In addition,the concentration of wood vinegar is not linear with the methane variation rate.The optimum concentration of wood vinegar is in the intermediate dilution gradient（A50）,and its methane variation rate is 22.98±5.82%.The effect of wood vinegar on the feed-liquid degradation characteristics of swine manure AD was studied:The VFAs concentration of A5 remained at a high level.The degradation rates of VFAs of A50 and A100 were higher than those of Control,which indicated that low concentration of wood vinegar additives had stronger ability to alleviate acid inhibition.The pH value of each group was negatively correlated with VFAs concentration.The average DOC concentration of A50 and A 100 was lower and A5 was the highest.The trace elements such as Na,Mg,K and Ca in wood vinegar enhance the tolerance of microorganisms to high concentration of ammonia nitrogen,thus reducing the concentration of ammonia nitrogen.The TS content,VS content and VS/TS of each experimental group decreased after AD,and the TS reduction,VS reduction and VS/TS reduction were positively correlated with the corresponding cumulative biogas/methane production.A50 had the best AD performance and the highest feed-liquid degradation efficiency.The effects of wood vinegar on the microbial community of swine manure AD were studied:High-throughput sequencing technology was used to analyze the abundance,diversity,differences and community structure changes of microbial communities before and after AD.The sampling coverage of microbial communities was high,and the diversity and richness of microbial communities increased after AD,especially in the A50 and A100treatment groups,their diversity was higher than that of Control.Through the combination analysis of Venn diagram and microbial community barplot with multiple samples similarity tree,it can be concluded that the microbial community in swine manure AD system can be clustered differently by adding different concentration of wood vinegar,and the difference of community structure between high concentration wood vinegar system and Control system is greater than that between low concentration wood vinegar system and Control system.Firmicutes and Bacteroidetes are the main phylum-level bacteria.At the end of AD,Firmicutes decreased while Bacteroidetes increased.The dominant Archaea of low concentration treatment（A50 and A 100）and A5 were Methanosarcina and Methanobrevibacter respectively.According to the metabolic pathway and relative abundance of methanogens,the methane production of A50 and A100 was higher than that of A5.Acetic acid was mainly degraded by Methanosarcina,propionic acid and butyric acid were mainly degraded by Methanosarcina and Methanobrevibacter. |
