Study on utilizing Chinese Baijiu wastewater as an alternative carbon source in full-scale municipal sewage treatment plants

Yellow water, a byproduct of solid-state fermented Chinese Baijiu production, contains high levels of chemical oxygen demand (COD), posing challenges for wastewater treatment but also offering potential as an external carbon source. This study investigates the viability of using yellow water as a carbon source in full-scale wastewater treatment plants (WWTPs). Compared to a commonly used compound carbon source, yellow water maintained high efficiencies in total nitrogen (TN) (82.94 ± 3.41 % vs. 83.50 ± 2.99 %) and COD removal (96.53 ± 1.00 % vs. 96.65 ± 0.77 %). Additionally, comparable specific denitrification (0.1264 ± 0.0082 g NO₃^--N g⁻¹ TSS d⁻¹ vs. 0.1157 ± 0.0126 g NO₃^--N g⁻¹ TSS d⁻¹) and specific nitrification rates (0.1164 ± 0.0121 g NH₄⁺-N g⁻¹ TSS d⁻¹ vs. 0.1092 ± 0.0063 g NH₄⁺-N g⁻¹ TSS d⁻¹) were observed. The addition of yellow water did not significantly affect the relative abundance of the microbial community. Furthermore, using yellow water could reduce costs by $13.27 per ton of Baijiu produced annually and avoid approximately 0.10 tons of CO₂ equivalent emissions per ton of Baijiu produced. This approach demonstrates significant potential for reducing the carbon footprint and costs associated with wastewater treatment in the Chinese Baijiu industry while promoting the recovery and reuse of wastewater resources, advancing sustainable wastewater treatment, and fostering a circular bioeconomy.