Temperature dependence of acids recovery from wastewater electro-fermentation

Temperature significantly influences fermentation, affecting microbial communities and metabolites. This study explored the impact of temperature on electrically regulated electro-fermentation, focusing on volatile fatty acid production at different temperatures (psychrophilic 10 °C, mesophilic 20 °C, and thermophilic 55 °C) under controlled anode potentials. Results showed that at 10 °C, propionic and valeric acid production increased, while at 20 °C, acetic and propionic acids were predominant. At 55 °C, more formic acid and ethanol were produced. The dominant microbial species varied with temperature: Lactococcus bacteria were prevalent in psychrophilic and mesophilic reactors, and thermophilic bacteria in the thermophilic reactors. Electrical potential had a minimal effect on acid products, but temperature significantly influenced them. Low temperatures favored propionic and valeric acid production, correlating with specific microbial abundance. Conversely, high temperatures led to increased formic acid and ethanol. These findings offer valuable insights for optimizing electro-fermentation systems and enhancing valuable fatty acid production.