沼液回流对牛粪厌氧发酵工程影响

EFFECT OF REFLUX RATIO OF BIOGAS SLURRY ON ANAEROBIC FERMENTATION OF COW MANURE

为了减少连续进料的湿式厌氧发酵工程产沼液量和出料热量损失,在50 L连续进料的湿式厌氧发酵装置中模拟实验研究长期回流沼液对牛粪厌氧发酵工程的影响,在中温(37±1)℃条件下研究不同沼液回流比例(0%、30%、40%、50%、60%)时日产气量、甲烷体积分数、pH值、SCOD含量和氨氮含量变化,并通过动力学分析回流对甲烷生产的促进机理。结果表明:回流比例为40%的试验组在回流阶段日产气量逐渐升高并在108 d后趋于稳定,在试验周期内最高日产气量为62.45 L,容积产气率为1.39 L/L,与回流比例为0%、30%的试验组相比分别提高25.46%、9.22%。回流比例为50%、60%的试验组在回流阶段内虽能更快达到最高日产气量62.29、62.40 L,但日产气量在第95天和第78天分别开始降低,至120 d试验结束时已低于回流比例为40%的试验组。最后理论计算回流沼液对发酵进料温度的提升,得出回流沼液可使发酵原料温升能耗降低27.23%~33.38%。

In order to reduce the biogas slurry and heat loss from the wet anaerobic fermentation process of continuous feeding,the effect of long-term reflux biogas slurry on the anaerobic fermentation of cow manure was studied in a 50 L continuous feed wet anaerobic fermentation plant.At the mesophile temperature(37±1)℃,the daily gas production,methane volume fraction,pH value,SCOD content and ammonia nitrogen content of biogas liquid reflux ratios(0%,30%,40%,50%,60%)were studied.And the mechanism of promoting the methane recovery is researched by kinetic analysis.The results show that the gas production in the test group with a reflux ratio of 40%gradually increases during the reflux phase and stabilizes after 108 days.The highest daily gas production during the test period is 62.45 L,and the volumetric gas production rate is 1.39 L/L.Compared with the test group with a reflux ratio of 0%and 30%,it is increased by 25.46%and 9.22%respectively.The test group with a reflux ratio of 50%and 60%achieves a maximum daily gas production of 62.29 L and 62.40 L in the reflux phase,but the daily gas production begin to decrease at the 95 th and 78 th day respectively,and at the end of the 120 d test,it is already below the test group with a reflux ratio of 40%.Finally,the theoretical calculation of the increase of the fermentation feed temperature by the reflux biogas slurry shows that the reflux biogas slurry can reduce the energy consumption of the fermentation raw material by 27.23%to 33.38%.