稻秸预处理厌氧强化产挥发性脂肪酸研究

摘要

The use of anaerobic fermentation technology of agriculture wastes for the production of volatile fatty acids (VFAs) is a promising approach.The aim of this investigation was to evaluate the different pretreatments of rice straw like hydrothermal,acid and alkali on the AD process parameters and the VFAs production at mesophilic (35℃),thermophilic (55℃) and hyper-thermophilic (70℃).The results showed that the alkaline pretreatment was more favorable for VFAs production than acid and hydrothermal treatments.The lignin degradation rate with Ca(OH)2 at 35℃ was 63.27％,which was much higher than that of hydrothermal treatment group (12.45％) and that of HCl treatment group (12.40％).The pH value was in the range of 6 + 0.5 at alkali pretreatment.The efficiency of converting the degraded straw into VFAs at mesophilic was high,resulting in the highest VFAs yield.The VFAs yield with per degradation volatile solid in the pretreatment group was 0.79 ～ 1.20 g/g and 0.24 ～ 0.51 g/g at 35℃ and 70℃,respectively.The preferred alkali treatment group gave a yield of VFAs production of 0.25 g/g at 35℃ and 0.09 g/g at 70℃,respectively.The results can provide some theoretical basis to enhance the VFAs production from rice straw under different conditions.%利用秸秆厌氧发酵技术进行挥发性脂肪酸(Volatile fatty acids,VFAs)生产,是一种极具前景的秸秆新型高值化利用方向.研究了水热、稀酸、稀碱等预处理方式在中温35℃、高温55℃、超高温70℃等发酵产酸温度条件下的产酸率及过程参数.结果表明,不同预处理条件对挥发性脂肪酸转化率影响从大到小为Ca(OH)2、HCl、水热预处理,碱性发酵较酸性发酵更有利于厌氧产挥发性脂肪酸进行.Ca(OH)2能够有效地溶解木质素,35℃时Ca(OH)2的木质素去除率为63.27％,远高于相同温度的水热处理组的12.45％和HCl处理组的12.40％.中温条件下秸秆挥发性脂肪酸产率最高,虽然35℃时因为温度较低使得秸秆降解率不高,但因该温度下被降解的秸秆转化为挥发性脂肪酸的效率高,从而获得了最高的产酸率,各预处理组单位降解底物产酸率在35℃和70℃分别为0.79～1.20 g/g和0.24～0.51 g/g.最佳的碱处理组35℃的挥发性脂肪酸底物挥发分转化率为0.25 g/g,而70℃时仅为0.09 g/g.研究结果为稻秸厌氧强化产挥发性脂肪酸的预处理和温度等选择提供了一定的理论依据.