Iron-Modified Biochar and Plant Species in Enhancing Wastewater Treatment in Constructed Wetlands.xlsx

Constructed wetlands (CWs) are an effective wastewater treatment technology, with biochar addition believed to further enhance their performance. This study investigated the effects of different “tea leaf-derived biochar loaded with Fe” (TBC-Fe) addition levels (0%, 1%, 2%) on wastewater treatment performance in CWs planted with three wetland plant species: Cyperus alternifolius (CA), Acorus calamus (AC) and Canna indica (CI). Through controlled experiments, we evaluated the effects of TBC-Fe on the removal efficiency of COD, TN, NH4+-N, NO3--N and TP, while also evaluating plant physiological responses. Results demonstrated that the appropriate biochar addition level (1%) significantly enhanced water quality improvement of CWs, and promoted plant growth, root metabolic activity and nutrient uptake (N and P). Among the plant species, the CA system showed the highest potential for pollutant removal. However, its dosage effect is significant, excessive addition of biochar (2%) led to reduced biomass, lower chlorophyll and carotenoid concentration and decreased photosynthesis efficiency, thereby impairing the CW performance. These findings suggest that TBC-Fe can significantly boost the water purification efficiency of CWs, but optimal dosages must be tailored to specific plant species and biochar characteristics for maximum effectiveness in both wastewater purification and plant growth.

人工湿地（Constructed Wetlands, CWs）是一种高效的污水处理技术，而添加生物炭被认为可进一步提升其处理效能。本研究探究了不同负载铁的茶源生物炭（Tea leaf-derived biochar loaded with Fe, TBC-Fe）添加梯度（0%、1%、2%）对种植3种湿地植物的人工湿地污水处理效能的影响，所选用的湿地植物分别为风车草（Cyperus alternifolius, CA）、菖蒲（Acorus calamus, AC）及美人蕉（Canna indica, CI）。本研究通过控制性实验，评估了TBC-Fe对化学需氧量（COD）、总氮（TN）、氨氮（NH4+-N）、硝态氮（NO3--N）及总磷（TP）的去除效果，同时测定了植物的生理响应指标。研究结果表明，适宜的生物炭添加量（1%）可显著提升人工湿地的水质净化效能，同时促进植物生长、根系代谢活性及氮（N）、磷（P）营养元素吸收。在3种供试植物中，种植风车草的人工湿地系统（CA系统）对污染物的去除潜力最强。但该效应存在显著的剂量依赖性：过量添加生物炭（2%）会导致植物生物量下降、叶绿素与类胡萝卜素含量降低，同时光合效率减弱，进而削弱人工湿地的整体处理效能。综上，TBC-Fe可显著提升人工湿地的水质净化效能，但需针对特定植物物种与生物炭特性优化添加剂量，以同时实现最优的污水处理效果与植物生长表现。