Evaluating optimized volatile fatty acids production from carbon-rich wastewater during hydrolysis acidification process by Fe(II) and Fe (III) addition

Volatile fatty acids (VFAs), a value product of hydrolysis acidification (HA) has been grasped ample eyeballs. Fe (II) and Fe(III) were applied to enhance VFAs production from carbon-rich starch wastewater in this investi-gation. VFAs productivity was improved 6.5-15.2% than the control system when Fe(II) and Fe(III) were sup-plemented. The enrichment of key functional HA microbes identified by molecular ecological network analysis (MENA) and improved key enzymes' activity contributed to promotion of organics hydrolysis, triggering high VFAs yields. After further analysis, it was clarified that the microbial metabolism's influence on pH and the presence of Fe2+ in the systems were key factors contributing to the improvement of the microbial community structure and the activity of key enzymes, respectively. Detailed comparison analysis was also conducted be-tween RFe(II) and RFe(III) systems. Totally, from the perspective of performance and environmental, Fe(II) and Fe(III) have great engineering application potential on enhancing VFAs production, especially for Fe(II).