Work

Substrate selection for optimizing swine tailwater treatment in vertical subsurface flow constructed wetlands: The superior performance of a biochar-manganese ore composite

Year: 2025

Type: article

Abstract: The increasing demand for pork has intensified environmental concerns related to swine farm wastewater, which contains high levels of nutrients, antibiotics, heavy metals, and antibiotic resistance genes (ARGs). This study evaluates the performance of four substrates-gravel, biochar, Mn ore, and a biochar/Mn ore mixture—in vertical subsurface flow constructed wetlands (VSFCWs) for the advanced treatment of swine tailwater. Batch adsorption experiments revealed that biochar and Mn ore exhibit superior adsorption capacities for antibiotics (17.95–106.97 μg·g −1 ) and copper (Cu, ~107 μg·g −1 ) compared to gravel (5.55–37.61 μg·g −1 ), with pseudo-second-order kinetics and Langmuir/Freundlich isotherms indicating chemisorption and multilayer adsorption mechanisms. Pilot-scale VSFCWs demonstrated excellent removal efficiencies for total organic carbon (TOC, 89.93–95.24 %), total nitrogen (TN, 90–96.98 %), ammonia nitrogen (NH₄ + -N, 93.94–98.16 %), phosphate (PO₄ 3− -P, 89.52–97.62 %), antibiotics (>94 %), Cu (>98 %), and ARGs (0.83–1.36 log units). Biochar-based systems (VSFCW-B and VSFCW-BM) outperformed others in removing TOC, TN, NH₄ + -N, antibiotics, and ARGs due to biochar's high surface area and microbial support, while gravel and Mn ore excelled in phosphorus removal. Further Microbial community analysis revealed that biochar-based systems fostered richer and more diverse bacterial communities. Environmental temperature significantly influenced pollutant removal, with low-level antibiotics (0.03–0.09 mg·L −1 ) and Cu (1.09 mg·L −1 ) enhancing nitrogen removal via co-metabolism. The biochar/Mn ore mixture is recommended for its synergistic performance in treating organic matter, sulfonamides, and ARGs, providing a cost-effective and environmentally friendly solution for swine tailwater reuse.

Source: Journal of Water Process Engineering

DOI: 10.1016/j.jwpe.2025.109350

Authors: Xinfeng Wang, Jialiang Zhang, Yun Ren, Yue Li, Shuqing Shang, Xinping Yang

Institution: Nanjing Agricultural University

Language: English

Topic: Constructed Wetlands for Wastewater Treatment

Subfield: Waste Management and Disposal

Field: Environmental Science

Domain: Physical Sciences

SDGs: Clean water and sanitation, Responsible consumption and production

Open Access status: hybrid

Estimated APC paid: $3,350