Tofu wastewater as a carbon source flowing into municipal wastewater treatment plants for reductions of costs and greenhouse gas emissions.
Hongbo Feng, Linyi Jin, Yongfeng Chen, Junchao Ji, Zhen Gong, Wangxian Hu, Chao Ying, Yifan Liang, Jun Li
Author Information
Hongbo Feng: Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China; Hangzhou Rian Ecological Environment Technology Co., Ltd., Hangzhou, 311201, China.
Linyi Jin: Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China.
Yongfeng Chen: Yiwu Water Treatment Co., Ltd., Jinhua, 322000, China.
Junchao Ji: Yiwu Water Treatment Co., Ltd., Jinhua, 322000, China.
Zhen Gong: Yiwu Water Treatment Co., Ltd., Jinhua, 322000, China.
Yifan Liang: Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China.
Jun Li: Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, China. Electronic address: tanweilijun@zjut.edu.cn.
Wastewater treatment processes significantly contribute to greenhouse gas (GHG) emissions. Municipal wastewater treatment also faces challenges related to low strength and a low carbon-to-nitrogen (C/N) ratio. This study investigates the high-carbon tofu wastewater flowing into municipal sewers for co-treatment at a wastewater treatment plant (WWTP) directly, with the goal of enhancing nitrogen removal and reduce GHG emissions. Within the framework of a circular economy for wastewater treatment, tofu wastewater serves as an external carbon source for sustainable solutions. The concentrated tofu wastewater had an average chemical oxygen demand (COD) of 21,894 �� 11,485 mg/L, total nitrogen (TN) of 591.8 �� 238.2 mg/L, and a C/N ratio of 36.9 �� 7.4. The denitrification rate reached 3.05 mg NO-N/(g MLVSS��h). Therefore, tofu wastewater is a suitable alternative carbon source. A full-scale WWTP with a capacity of 20,000 m��/day was monitored from 2017 to 2022 to evaluate the co-treatment effects of municipal wastewater and tofu wastewater. The results showed an increase in 53.3% in the average COD concentration of the influent wastewater, while the total nitrogen and total phosphorus removal efficiencies were enhanced to 75.8% and 95.2%, respectively. In addition, the study quantified GHG emissions from tofu wastewater and municipal wastewater treatment. Compared to separate treatment processes, the co-treatment reduced GHG emissions by 337.9 t CO-eq., approximately 15.8% of the total emissions of WWTP, and achieved a cost saving of 7-10% of the total operational costs. These findings demonstrate the environmental and economic advantages of integrating high-carbon industrial wastewater treatment directly into wastewater treatment plants.
