高压均质对蓝藻有机质释放与厌氧发酵产酸的促进效果

为提高蓝藻在厌氧发酵过程中的资源化利用率，采用高压均质技术处理蓝藻以提高其厌氧发酵产VFAs（挥发性脂肪酸）的效率，通过对蓝藻进行不同压力和pH的高压均质处理，比较处理后蓝藻营养物质的释放情况，并确定该处理的优选运行条件；同时，对未处理蓝藻、高压均质蓝藻、热碱蓝藻进行厌氧发酵试验，评估高压均质处理对蓝藻发酵产酸效果的影响.结果表明:不同条件下高压均质的蓝藻所释放的有机质均较处理前有所提高，其中高压均质的优选条件为压力100 MPa和pH=11，该条件下ρ（SCOD）（SCOD为溶解性化学需氧量）可达22.74 g/L，比对照组提高了52.34倍.在厌氧发酵试验中，高压均质处理在促进有机质释放的同时，还可以提高底物的可生化性，进而提升产酸量.高压均质蓝藻产VFAs的质量浓度最高达8.22 g/L，是对照组的2.16倍.另外，高压均质处理蓝藻的CST（毛细吸水时间）由热碱预处理蓝藻的2 940 s降至1 940 s，减缓了有机质释放带来的脱水性能的恶化趋势.研究显示，高压均质预处理能够提高蓝藻细胞有机质释放、改善碳源可生化性、促进厌氧发酵产酸量，并且降低了分离回收碳源的难度. 

Enhanced Cyanobacteria Organic Release and Anaerobic Fermentation for VFAs Production by High-Pressure Homogenization

To improve cyanobacteria utilization rate in anaerobic fermentation, high-pressure homogenization pretreatment was used in this study to accelerate organics releasing from cyanobacteria and to improve its anaerobic fermentation for VFAs (volatile fatty acids) production. The influences of high-pressure homogenization pretreatment on the physicochemical properties of cyanobacteria, as well as the efficiency of its anaerobic fermentation for VFAs production were investigated. The best conditions for high-pressure homogenization were selected by considering performances of organics releases under different pressures and pH. The improvement of high-pressure homogenization to VFAs production from anaerobic fermentation of cyanobacteria were evaluated by the compositions of the VFAs produced from cyanobacteria unpretreated, pretreated by thermal alkaline and pretreated by high-pressure homogeneous. The results indicate that organics releases could be accelerated by high-pressure homogenization with different operation indexes, while 100 MPa and pH=11 were the optimal, and under which, the concentration of the released SCOD (soluble chemical oxygen demand) could reached as high as 22.74 g/L, which was 52.34 times higher than that in the raw cyanobacteria before pretreatment. Moreover, during anaerobic fermentation experiments, the biodegradability of organics released from cyanobacteria could also be greatly improved, thereby increasing VFAs production. The volatile fatty acids yield of cyanobacteria pretreated by high-pressure homogeneous reached 8.22 g/L by anaerobic fermentation, which was 2.16 times of the control. Furthermore, high-pressure homogenization could alleviate the deterioration of cyanobacteria dewaterability due to organics release. Although the CST (capillary suction time) of homogeneous cyanobacteria presented the largest value of about 1940 s, it was much smaller than that in the group with thermal alkaline pretreatment, about 2940 s. Therefore, it can be concluded that high-pressure homogenization can enhance the release of organics in cyanobacteria, improve the biodegradability of carbon sources, promote VFAs production from anaerobic fermentation and reduce the difficulty in separating and recovering carbon sources.