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为了解紧实度和温度对秸秆水解产酸过程的影响,以麦秸为原料,在不密封条件下,设置秸秆容重分别为0.03、0.05和0.08 t·m-3,水解温度为10、20和30℃,分析了实验过程中水解酸化液COD、SCOD、pH值、挥发性脂肪酸组成和含量的变化。结果表明:秸秆紧实度对秸秆有机物水解溶出速率影响明显,秸秆紧实度与秸秆有机物水解溶出速率成反比,与水解酸化液COD、SCOD和挥发性脂肪酸含量达到峰值的时间成正比,但在同等体积反应器内紧实度越大秸秆TS负荷越高,有利于提高水解酸化液COD、SCOD和VFAs浓度;秸秆紧实度对秸秆水解产酸产物的组成和含量影响明显,秸秆容重为0.03和0.05 t·m-3的处理水解产酸产物中乙酸占比达75%以上,丙酸、丁酸等含量较低,而秸秆容重为0.08 t·m-3的处理水解产酸产物中以丁酸和乙酸为主,为典型的丁酸型发酵,11 d后转变为丙酸型发酵;实验12 d后,不同紧实度处理水解酸化液中丙酸含量均逐渐增加;温度对秸秆有机物水解溶出的影响明显,水解酸化液COD、SCOD和pH值与温度成正比,温度高对秸秆有机物水解溶出有利,但同时也提高了可分解利用秸秆水解产酸产物的微生物活性,造成实验后期水解产酸产物大量损失。当温度为30℃时,水解产酸时间控制在5 d左右较合适,当温度为20℃时,水解产酸时间控制在2周左右较合适。
In order to understand the effect of compaction and temperature on the hydrolysis and acidification of straw, wheat straw was used as raw material. Under unsealed condition, the straw bulk density was set at 0.03,0.05 and 0.08 t · m-3, respectively. The hydrolysis temperature was 10, 20 and 30 ℃, the changes of COD, SCOD, pH value, volatile fatty acid composition and content in the hydrolyzed acidified liquid during the experiment were analyzed. The results showed that straw compaction had a significant effect on the rate of hydrolysis and dissolution of straw organic matter. The compaction degree of straw was inversely proportional to the rate of hydrolysis and dissolution of straw organic matter, and it was directly proportional to the peak time of COD, SCOD and volatile fatty acid The higher the compaction degree in the same volume reactor, the higher the TS load of straw is, which is beneficial to increase the concentration of COD, SCOD and VFAs in the acidified hydrolyzate. The compaction of straw has an obvious effect on the composition and content of hydrolyzed and acidified products, And acetic acid accounted for more than 75% in the hydrolyzed acidification products with 0.05 t · m-3, but propanoic acid and butyric acid were lower in the hydrolysis and acidification products with straw bulk density of 0.08 t · m-3 Butyric acid and acetic acid were the main types of butyric acid fermentation, which changed to propionic acid type fermentation after 11 days. After 12 days of experiment, the content of propionic acid in hydrolyzed acidification solution with different compaction degrees increased gradually. The effect of hydrolysis and dissolution is obvious. COD, SCOD and pH value of hydrolysis acidification solution are directly proportional to temperature. High temperature is beneficial to the hydrolysis and dissolution of straw organic matter, but also increases the activity of microorganisms that can decompose and utilize straw hydrolyzed acid product, Post-hydrolysis yield the acid product substantial loss. When the temperature is 30 ℃, the acid hydrolysis time is controlled at about 5 d. When the temperature is 20 ℃, it is more suitable to control the hydrolysis and acid production time at about 2 weeks.