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Updated: Oct 13, 2025

Medium Preparation for the Cultivation of Microorganisms under Strictly Anaerobic/Anoxic Conditions
Published on: August 15, 2019
pH and hydraulic retention time regulation for anaerobic fermentation: Focus on volatile fatty acids
Nan Lv1, Guanjing Cai2, Xiaofang Pan3
1Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China; School of Environment and Nature Resources, Renmin University of China, Beijing 100872, China; Key Laboratory of Energy Resource Utilization from Agriculture Residue, Ministry of Agriculture and Rural Affairs, China.
Abstract:
Enriching suitable fermentative products by optimizing operation conditions could effectively improve the efficiency of anaerobic digestion. In the present study, pH (5.0-6.0) and hydraulic retention time (HRT) (2 h-12 h) were regulated for volatile fatty acids (VFAs) production during glucose fermentation in acidogenic continuous stirred tank reactor (CSTR). Results showed that acetate and butyrate dominated during pH regulation. HRT reduction favored butyrate production and formate retainment. Maximum total VFAs production with highest acetate content was achieved at pH of 6.0 and HRT of 6 h. Microbial analysis revealed that Clostridium_sensu_stricto_1 was predominant butyrate producer during pH regulation, and Bacteroides was main contributor when HRT shorter than 6 h. In addition to acetyl-CoA pathway, acetate could also be produced via homoacetogenesis by Parabacteroides, UCG-004 and norank_f__Acidaminococcaceae. These results would give guidance for enhancing targeted VFAs products by optimizing operational parameters or bio-augmentation with specific bacteria.
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