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Intracellular polymers production in anaerobic sludge under salt shock and batch fermentation conditions: Experimental and modelling study

Huang, Liang, Fu, Xian-Zhong, Cui, Shuo, Liu, Hou-Qi, Yu, Han-Qing, Li, Wen-Wei
Biochemical engineering journal 2019 v.142 pp. 68-73
anaerobic digestion, batch fermentation, biochemical pathways, carbon, carbon sequestration, electrons, glucose, mathematical models, monitoring, osmotic pressure, polymers, salinity, sludge, sodium chloride, solutes, volatile fatty acids, wastewater, wastewater treatment
High salinity can suppress the metabolic activities of anaerobic sludge in treating saline organic wastewater, but its impacts on production of intracellular polymers, which play important roles in microbial metabolism and carbon storage, remain unclear. This work examined the dynamics of intracellular polymers, functioning as microbial storage (for supplementing re-utilizable carbon source) and compatible solutes (for equalizing the salinity-induced osmotic pressure) respectively, in response to salinity (0–30 g/L NaCl) and evaluated their impacts on glucose transformation in a batch-fed anaerobic digestion (AD) system. Based on the experimental data, a mathematical model was developed to distinguish the stored carbohydrates and compatible solutes, and quantify the metabolic products. The results show a significantly stimulated formation of compatible solutes and a suppressed production of stored carbohydrates and volatile fatty acids (VFAs) under the salinity shock, due to their competition for substrate electrons. Taking into account the dynamics of intracellular polymers, the model in this study provides a more accurate description on the batch AD process under salinity shock than the existing Anaerobic Digestion Model No. 1 (ADM1) proposed by the International Water Association (IWA). This work may lay a solid basis for improved monitoring and optimization of practical saline wastewater treatment processes.