| In recent years,putrescible waste has become the major part of rural domestic waste,putting tremendous pressure on soil,water and atmospheric environment in rural areas.As a resource-utilizing method with simple process,low operating cost and high degree of harmlessness,aerobic composting is suitable for treating putrescible waste with high organic matter content.However,the putrescible waste material is difficult to provide a suitable growth and metabolism environment for aerobic microorganisms,and it is impossible to carry out effective temperature rise and humification conversion.At the same time,a large amount of odorous gas such as ammoniagenerated during the composting process will cause secondary pollution to the environment.In order to solve the practical problems in the aerobic composting of putrescible waste,bulking agents and nitrogen-fixing agents were adopted to adjust the rural putrescible waste materials to improve the effect of aerobic composting and achieve the purpose of reducing ammonia emissions and reducing nutrient loss.Also it could provide theoretical guidance for production applications.At the same time,the effects of organic matter and nitrogen transformation during the composting process and the effects of different conditioning agents on the bacterial community structure were studied,which provided scientific significance for the research of aerobic composting conditioner for putrescible waste.The main results were concluded as follows:1.The effects of different bulkings agents on the aerobic composting of putrescible waste.Three bulking agents including saw dust,matured compost and wheat bran were used to adjust the putrescible waste and to explore the effect on aerobic composting.The results showed that due to the high initial moisture content(75%)and poor permeability of the putrescible waste material,the maximum temperature of the compost was only 42?,which could not achieve the purpose of harmless treatment.The addition of bulking agents can improve the properties of the initial material and significantly improve the composting effect.Under the condition of controlling the initial moisture content of 60%,the wheat bran addition group had the longest duration in the high temperature period(5 days),lowest moisture content of the final compost(22.1%),highest degradation rate of organic matter(54.6%),most prominent change in C/N(T=0.51)and with the final weight loss rate of 69.2%and germination index of 112%,all reached the quality requirements of composting.The conditioning effect of wheat bran was significantly better than that of saw dust and matured compost,therefore it can be used as an ideal bulking agent for rural putrescible waste composting.2.The effects of different nitrogen-fixing agents on NH3 emission reduction and nitrogen conversion in putrescible waste compost.Taking the putrescible waste with wheat bran as the research object,bamboo charcoal,zeolite and calcium superphosphate were used as nitrogen-fixing agents to explore the effect in reducing ammonia volatilization and nitrogen conversion during composting.The results showed that all the nitrogen-fixing agent addition groups were able to carry out a good high-temperature composting process and finally reached a better state of maturity.The addition of nitrogen-fixing agents could significantly reduce the generation of ammonia in the composting process.Under the condition of 5%addition,the bamboo charcoal,zeolite and calcium superphosphate addition groups reduced the total ammonia emission by 40.8%,40.1%and 47.3%,respectively.The effect of calcium superphosphate was the best but resulted in the exceeding standard of electrical conductivity.At the same time,the change of nitrogen in the materials of each group in the composting process showed similar regularity.The addition of nitrogen-fixing agents can effectively reduce the nitrogen loss of the compost,the use of bamboo charcoal,zeolite and calcium superphosphate reduced the total nitrogen loss by 26.0%,24.1%and 37.9%,respectively.3.The effects of bulking agents and nitrogen-fixing agents on bacterial community structure and succession during composting.High-throughput sequencing technology was used to study the effects of different bulking agents and nitrogen-fixing agents on the changes of bacterial community structure in the compost.The results showed each of the bulking agent addition groups showed significant differences in bacterial community abundance,diversity and structure.Most of the bacteria in compost were composed of Firmicutes,Proteobacteria,Bacteroidetes and Actinobacteria.The addition of bulking agents had a significant effect on the bacterial community structure in the compost.The four groups were dominated by Clostridia,Gammaproteobacteria,Bacilli,and Flavobacteriia in the high temperature period.They were similarly dominated by Bacilli in the stationary phase,but there was a big difference in the distribution of genus.The addition of nitrogen-fixing agents was beneficial to increase the abundance and diversity of bacterial communities during high temperature periods.At this time,the diversity of bacteria related with organic matter degradation was strong,among which Bacillus and Saccharomonospora were the main functional floras.Other bacterial floras such as Saccharopolyspora,Sphingobacterium and Staphylococcus could be affected by different nitrogen-fixing agents.Ureibacillus which may be associated with compost maturity was detected in the compost of stationary phase.The addition of bamboo charcoal had the effect of increasing the diversity of bacterial communities and in the stationary phase and could increase the metabolic activity of microorganisms. |
PDF Full Text Request