Optimization of Fermentation Parameters for the Sustainable Production of Effective Carbon Sources from Kitchen Waste to Enhance Nutrient Removal in Sewage

Abstract

In this study, we optimize the kitchen waste fermentation process by adjusting the fermentation time and temperature to prepare high-efficiency carbon sources to enhance nitrogen and phosphorus removal during sewage treatment. Simulated kitchen waste fermentation experiments were performed, and the impact on the pollutant removal efficiencies was analyzed using a sequence batch reactor (SBR). The results showed that the volatile fatty acid (VFA) concentration peak occurred on the first day of fermentation, the maximum increment was 543.19 mg/L, and the maximum soluble chemical oxygen demand/total nitrogen (COD/TN) ratio was 40.49. However, the highest total nitrogen (TN) removal efficiency was 70.42% on the second day of fermentation. An increase in temperature promoted organic matter release, with the highest soluble COD concentration of 22.69 g/L observed at 45 °C. Further, the maximum VFAs production (935.08–985.13 mg/L) occurred from 25 to 35 °C. In addition, the fermentation products in this temperature range also showed the optimal removal efficiencies for total phosphorus (TP) and TN at 91.50% and 79.63%, respectively. Although 15 °C and 45 °C were beneficial for COD reduction, they were not conducive to nitrogen and phosphorus removal. The energy consumption and the synergistic pollutant removal showed that the optimal fermentation conditions were 2 days at 35 °C. Under these conditions, the kitchen waste-derived carbon source achieved efficient TN and TP removal, as well as COD reduction. Therefore, these conditions provide a feasible solution for the “reduction and sustainability” of kitchen waste.