Full-Scale Efficient Production and Economic Analysis of SCFAs from UPOW and Its Application as a Carbon Source for Sustainable Wastewater Biological Treatment

There are large amounts of carbohydrates and proteins in rban perishable organic waste (UPOW), which can be converted to short chain fatty acids (SCFAs) through microbial methods. In this study, the mass balance and properties of organic slurry generated from UPOW pretreatment were investigated first. Then, the optimal conditions for SCFAs production from organic slurry of UPOW was studied. It was found that under the conditions of pH 8 ± 0.5 and reaction time of 3 d, the yield of SCFAs, mainly composed of acetic and propionic acids, in the full-scale reactor was 0.68 gCOD/gTCOD of organic slurry. Under the conditions of influent NH₄⁺-N, total nitrogen, soluble ortho-phosphorus, and soluble COD of 27–39, 33–45, 2–9, and 220–300 mg/L, respectively, the use of SCFAs-enriched fermentation liquid (100 mg COD/L) as the additional carbon source for full-scale biological municipal wastewater treatment showed a higher total nitrogen and phosphorus removal efficiency than that of sodium acetate (88.1 ± 5.2% against 81.4 ± 4.5% and 96.9 ± 3.1% versus 91.5 ± 2.8%) due to greater key enzyme activity and short-cut nitrification and denitrification capacity. Finally, based on the actual operation process, an economic benefit analysis on the production of SCFAs-enriched fermentation liquid from UPOW was conducted, and the issues that need to be addressed for the promotion and application of this technology were discussed. This study contributes to achieving sustainable synergistic treatment of organic waste and wastewater.