Lu Qi, Liu Qiang, Liu Xuran, Li Yifu, Yin Zhuo, Wang Dongbo
Department of Urology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China; College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha, 410082, PR China.
Department of Urology, Second Xiangya Hospital, Central South University, Changsha, 410011, PR China; College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha, 410082, PR China.
J Environ Manage. 2022 Dec 1;323:116212. doi: 10.1016/j.jenvman.2022.116212. Epub 2022 Sep 21.
The poor dewaterability of fermented sludge is an important factor limiting the development of anaerobic fermentation applications. Herein we reported an efficient strategy, i.e., using acidic regulation to stimulate the release of indigenous enzymes, to enhance the hydrolysis and dewatering of fermented sludge. The results showed that after acidic regulation at pH 4.0 for 1 day, the activity of protease and α-glucosidase were improved by 131.4% and 146.0%, while the capillary suction time and specific resistance to filtration were decreased by 93.8% and 69.5%, respectively. Mechanism study revealed that the method firstly destroyed the slime and bound EPS and cells of fermented sludge, causing the release of indigenous enzymes (i.e., protease and α-glucosidase) contained in. Then, the released enzymes directly accelerated the hydrolysis and acidification of fragmentized extracellular polymeric substances, thereby benefited the release of bound water in sludge particles. Finally, such acidic condition decreased the electrostatic repulsive interactions between destroyed sludge particles, further improving their flocculation. The findings not only deepen the understanding of indigenous enzymes contained in fermented sludge affecting sludge dewatering, but also might guide engineers to develop promising strategies to facilitate fermented sludge dewatering and fermentation liquid recovery in the future.
发酵污泥脱水性能差是限制厌氧发酵应用发展的一个重要因素。在此，我们报道了一种有效的策略，即利用酸性调节来刺激内源酶的释放，以增强发酵污泥的水解和脱水效果。结果表明，在pH 4.0下进行1天的酸性调节后，蛋白酶和α-葡萄糖苷酶的活性分别提高了131.4%和146.0%，而毛细吸水时间和比过滤阻力分别降低了93.8%和69.5%。机理研究表明，该方法首先破坏了发酵污泥的黏液层、结合态胞外聚合物和细胞，促使其中所含的内源酶（即蛋白酶和α-葡萄糖苷酶）释放出来。然后，释放出的酶直接加速了破碎的胞外聚合物的水解和酸化，从而有利于污泥颗粒中结合水的释放。最后，这种酸性条件降低了被破坏的污泥颗粒之间的静电排斥相互作用，进一步改善了它们的絮凝效果。这些发现不仅加深了我们对发酵污泥中内源酶影响污泥脱水的理解，还可能指导工程师们在未来制定出有前景的策略，以促进发酵污泥的脱水和发酵液回收。
