The introduction of influent sulfamethoxazole loads induces changes in the removal pathways of sulfamethoxazole in vertical flow constructed wetlands featuring hematite substrate

• Published in: Journal of hazardous materials Vol. 469; p. 133964
• Main Authors: Cui, Erping, Fan, Xiangyang, Cui, Bingjian, Li, Shengshu, Chen, Taotao, Gao, Feng, Li, Jianan, Zhou, Zhenchao
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.05.2024
• Subjects: adsorption; Bacterial community; biodegradation; Constructed wetland; Hematite; Influent load; metagenomics; rivers; sand; Sulfamethoxazole; wastewater; Hematite; Sulfamethoxazole; Influent load; Constructed wetland; Bacterial community
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.133964

High frequent detection of sulfamethoxazole (SMX) in wastewater cannot be effectively removed by constructed wetlands (CWs) with a traditional river sand substrate. The role of emerging substrate of hematite in promoting SMX removal and the effect of influent SMX loads remain unclear. The removal efficiency of SMX in hematite CWs was significantly higher than that in river sand CWs by 12.7–13.8% by improving substrate adsorption capacity, plant uptake and microbial degradation. With increasing influent SMX load, the removal efficiency of SMX in hematite CWs slightly increased, and the removal pathways varied significantly. The contribution of plant uptake was relatively small (< 0.1%) under different influent SMX loads. Substrate adsorption (37.8%) primarily contributed to SMX removal in hematite CWs treated with low-influent SMX. Higher influent SMX loads decreased the contribution of substrate adsorption, and microbial degradation (67.0%) became the main removal pathway. Metagenomic analyses revealed that the rising influent load increased the abundance of SMX-degrading relative bacteria and the activity of key enzymes. Moreover, the abundance of high-risk ARGs and sulfonamide resistance genes in hematite CWs did not increase with the increasing influent load. This study elucidates the potential improvements in CWs with hematite introduction under different influent SMX loads. [Display omitted] •Hematite CW removed 12.7–13.8% more SMX than river sand CWs.•Influent SMX load in hematite CWs changed the SMX removal pathway.•Contribution of substrate adsorption decreased with the increasing influent SMX load.•Biodegradation mainly contributed to SMX removal under high influent SMX load.•High-risk ARGs showed no difference when increasing the influent SMX load.