不同类型原料发酵产气规律及影响因素研究

发布时间：2018-06-08 06:04

本文选题：牛粪 + 麦秸秆　；参考：《重庆大学》2016年硕士论文

【摘要】：随着我国畜牧业规模的不断扩大,为沼气工程提供了巨大的发展空间,采用禽畜粪便生产沼气,不仅能解决禽畜粪便造成的环境污染,还能实现禽畜粪便的资源再利用。实际沼气工程中,发酵原料是以单一禽畜粪便为主,这类禽畜粪便中,易降解物质少,营养成分不高,导致厌氧发酵产气量低下。为了解决这一问题,在禽畜粪便中加入含碳量高的秸秆类作物混合发酵来提高产气量,同时为秸秆的减量化和资源化利用提供一条途径。本实验以牛粪和麦秸秆为原料,研究不同固体含量(TS)下,单一牛粪、牛粪与麦秸秆按干物质质量2:1混合厌氧发酵及牛粪与预处理麦秸秆按干物质质量2:1混合厌氧发酵对产气速率、产气量、CH4含量和PH的影响,得出最佳的厌氧发酵条件。研究成果如下:(1)TS相同时,牛粪与麦秸秆或预处理麦秸秆混合厌氧发酵产气能力远优于单一牛粪厌氧发酵。TS=7.36%时,混合厌氧发酵的产气量是单一牛粪厌氧发酵的1.63~1.71倍;TS=10%时,混合厌氧发酵的产气量是单一牛粪厌氧发酵的2.01~2.14倍。(2)将麦秸秆预处理后与牛粪混合厌氧发酵,能够加快原料中有机物的降解和沼气产生,有利于缩短产气周期。(3)提高发酵原料的TS,产气量提高,但原料利用水平降低。本次对比实验中,发酵料液容积相同:单一牛粪厌氧发酵,TS=10%时的产气量比TS=7.36%时提高16%,原料产气率降低26%;牛粪与麦秸秆混合发酵时,TS=10%时的产气量比TS=7.36%时提高44%,原料产气率降低8.2%;牛粪与预处理麦秸秆混合发酵时,TS=10%时的产气量比TS=7.36%时提高45%,原料产气率降低8.4%;说明在实际进行沼气发酵,要根据实际的情况来选择最佳的TS。(4)将各组PH值变化范围对比发现:单一牛粪厌氧发酵PH值变化最小,牛粪与麦秸秆混合厌氧发酵次之,牛粪与预处理麦秸秆混合厌氧发酵PH变化范围最显著,呈酸化趋势。(5)发酵原料中C元素经过一系列复杂的生物和化学反应过后,仅有24%~42%的C元素转化到沼气中,其中,TS=7.36%时,有56.81%~57.14%转化到CH4中,TS=10%时,有52.22%~54.07%转化到CH4中,剩余的C元素部分被微生物利用,部分随反应的停止沉积在发酵罐底部。(6)在实际工程应用中的启示,为得到最大平均日产气量,发酵罐每次要完全换料且换料时间间隔:单一牛粪、牛粪与麦秸秆混合和牛粪与预处理麦秸秆混合发酵分别控制在7~10、15~18、9天范围内。
[Abstract]:With the continuous expansion of animal husbandry in China, biogas engineering has provided a huge space for development. The use of livestock manure to produce biogas can not only solve the environmental pollution caused by livestock manure, but also realize the reuse of livestock manure resources. In the actual biogas engineering, the main raw material for fermentation is single animal manure. In this kind of animal excrement, it is easy to degrade substances and its nutrition is not high, which leads to the low production of anaerobic fermentation gas. In order to solve this problem, mixed fermentation of straw crops with high carbon content was added to livestock feces to increase gas production, and to provide a way for the reduction and utilization of straw. In this experiment, cattle dung and wheat straw were used as raw materials to study single cow dung under different solid content. The effects of mixed anaerobic fermentation of cow dung and wheat straw at 2:1 dry mass and mixed anaerobic fermentation of cow dung and pretreated wheat straw at 2:1 on gas production rate, gas yield, Ch _ 4 content and PH were obtained. The optimum anaerobic fermentation conditions were obtained. The results showed that the gas production capacity of mixed anaerobic fermentation of cow dung and wheat straw or pretreated wheat straw was much better than that of single cow manure anaerobic fermentation. TS = 7.36. The gas production of mixed anaerobic fermentation was 1.63 ~ 1.71 times that of single cow dung anaerobic fermentation, and the gas production of mixed anaerobic fermentation was 1.63 ~ 1.71 times than that of single cow manure anaerobic fermentation. The gas production of mixed anaerobic fermentation was 2.01g 2.14 times than that of single cow dung fermentation. The mixture of wheat straw and cow dung could accelerate the degradation of organic matter and the production of biogas. It is advantageous to shorten the gas production cycle. 3) to increase the TSs of fermented raw materials, but the utilization level of raw materials is decreased. In this comparative experiment, The volume of fermentation material was the same: the gas production of single cow manure anaerobic fermentation was 16% higher than that of TS = 7.36, the gas production rate of raw material decreased 26%, the gas production of cattle dung and wheat straw mixed fermentation was 4444% higher than that of TS = 7.36, and the gas production rate of cow dung decreased 8.2%. In mixed fermentation with pretreated wheat straw, the gas production at 10% TS = 10 is 45% higher than that when TS = 7.36, and the gas production rate of raw material decreases by 8.4%, which indicates that biogas fermentation is carried out in practice. According to the actual situation, we should select the best TS.4) and compare the range of PH in each group. The results showed that the pH value of single cow manure anaerobic fermentation was the least, and the mixed anaerobic fermentation of cow dung and wheat straw was the second. After a series of complex biological and chemical reactions, only 24% of C was converted to biogas, and when TS = 7.36%, only 24% of C was converted into biogas. 56.81% of them were converted to Ch _ 4, 54.07% of them were transferred to Ch _ 4, and some of the remaining C elements were used by microbes, and some of them were deposited in the bottom of fermentor with the stop of reaction. 6) in practical engineering applications, to obtain the maximum average daily gas production, The fermentation tank should be completely restocked each time and the interval of reloading time: single cow dung mixed with wheat straw and mixed fermentation of cow dung and pretreated wheat straw were controlled in the range of 189 days respectively.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S216.4;X713

【相似文献】