Evaluation of Efficiently Removing Secondary Effluent Organic Matters (EfOM) by Al-Based Coagulant for Wastewater Recycling: A Case Study with an Industrial-Scale Food-Processing Wastewater Treatment Plant

• Published in: Membranes (Basel) Vol. 13; no. 5; p. 510
• Main Authors: Cheng, Yu, Cheng, Qiangqiang, Zhao, Chengjin, Ren, Xianghao, Wang, Yu, Kou, Yingying, Chon, Kangmin, Ko, Myung-Han, Hwang, Moon-Hyun
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 12.05.2023; MDPI
• Subjects: Acids; Aluminum sulfate; Aromaticity; Case studies; Chemical oxygen demand; Coagulants; Coagulation; Efficiency; Effluent treatment; Effluents; Flocculation; Food industries wastewaters; Food plants; Food processing; Food processing industry; Fourier transforms; humic-like substance; Hydrophobicity; Infrared spectroscopy; Microorganisms; Organic matter; organic matters; Polyacrylamide; Processing industry; Proteins; Purification; Quality standards; secondary effluent; Sewage; Sludge; soluble microbial products; Spectrum analysis; Sustainable development; Technology application; Turbidity; Wastewater reuse; Wastewater treatment; Wastewater treatment plants; Water reuse; Water treatment; Water treatment plants; South Korea; China; Fiji; United Kingdom > UK; Beijing China; secondary effluent; soluble microbial products; organic matters; water reuse; humic-like substance; coagulation
• ISSN: 2077-0375; 2077-0375
• DOI: 10.3390/membranes13050510

The reuse of wastewater has been identified as an important initiative for the sustainable development of the environment; thus, the removal of secondary effluent organic matter (EfOM) to ensure the safety of reused wastewater is the key step and a subject of extensive research. In this study, Al2(SO4)3 and anionic polyacrylamide were selected as coagulant and flocculant, respectively, for the treatment of secondary effluent from a food-processing industry wastewater treatment plant to meet the standard regulatory specifications for water reuse. In this process, the removal efficiencies of chemical oxygen demand (COD), components with UV254, and specific ultraviolet absorbance (SUVA) were 44.61%, 25.13%, and 9.13%, respectively, with an associated reduction in chroma and turbidity. The fluorescence intensities (Fmax) of two humic-like components were reduced during coagulation, and microbial humic-like components of EfOM had a better removal efficiency because of a higher Log Km value of 4.12. Fourier transform infrared spectroscopy showed that Al2(SO4)3 could remove the protein fraction of the soluble microbial products (SMP) of EfOM by forming a loose SMP protein complex with enhanced hydrophobicity. Furthermore, flocculation reduced the aromaticity of secondary effluent. The cost of the proposed secondary effluent treatment was 0.034 CNY t−1 %COD−1. These results demonstrate that the process is efficient and economically viable for EfOM removal to realize food-processing wastewater reuse.