人工湿地去除三唑磷的生物学机制初步研究

构建了以陶粒为基质、种植美人蕉（Canna indica）的水平潜流人工湿地小试系统,研究了该人工湿地系统对水体中三唑磷（triazophos,TAP）的去除效果,通过测定基质酶脲酶和碱性磷酸活性、微生物种群特征及植物根系超氧化物歧化酶和过氧化物酶活性,初步探讨了该人工湿地系统去除水体TAP的生物学机制。实验结果表明,在进水TAP浓度分别为0 mg·L-1（对照CW1）、0.1 mg·L-1（低浓度CW2）、1 mg·L-1（中浓度CW3）和5 mg·L-1（高浓度CW4）的条件下,人工湿地对水体中三唑磷具有良好的去除效果,去除率分别是96.4%、96.8%和53.7%。在进水TAP浓度越高的人工湿地系统中,进水端基质脲酶和碱性磷酸酶活性越高。中、高TAP浓度进水的系统中脲酶活性分别高于对照系统21.8%和29.2%。高TAP浓度进水的系统中碱性磷酸酶活性分别高于对照和低浓度进水系统51.7%和36.3%（p〈0.05）。比较进水端而言,各系统出水端的酶活性显著降低（p〈0.05）。相关性分析结果显示系统TAP的去除与基质中碱性磷酸酶活性呈显著正相关（p〈0.05）,表明基质中脲酶、碱性磷酸酶在人工湿地去除TAP过程中发挥重要作用。对各人工湿地系统基质中微生物进行分离纯化,并通过16S rDNA基因测序,结果表明,进水含TAP系统的进水端基质中均存在能够促进植物对氮磷营养元素的吸收以及与有机物降解密切相关的菌种,尤其在高TAP浓度进水的系统中发现一株含脱氨酶基因（acds）的菌株,能够促进有机磷降解中间产物—有机胺类的降解转化。此外,美人蕉根系超氧化物歧化酶和过氧化物酶活性在进水TAP浓度升高的情况下,呈现显著增强态势（p〈0.05）,并正常生长,说明美人蕉对TAP具有较好的抵抗能力。     

Removal of arsenic by pilot-scale vertical flow constructed wetland

• VFCWs are effective for the treatment of arsenic-containing wastewater. • Arsenic removal did not affect the removal of nutrients, except for TP in CW500. • Arsenic removal was highest when the temperature peaked and the reed was in bloom. • Substrate accumulation contributed more to arsenic removal than plant absorption. Four pilot-scale Vertical Flow Constructed Wetlands (VFCWs) filled with gravel and planted with Phragmites australis were operated for seven months in the field to study the efficiency of arsenic removal in contaminated wastewater. The average arsenic removal efficiency by the VFCWs was 52.0%±20.2%, 52.9%±21.3%, and 40.3%±19.4% at the theoretical concentrations of 50 μg/L (CW50), 100 μg/L (CW100), and 500 μg/L (CW500) arsenic in the wastewater, respectively. The results also showed no significant differences in the removal efficiency for conventional contaminants (nitrogen, phosphorus, or chemical oxygen demand) between wastewater treatments that did or did not contain arsenic (P>0.05), except for phosphorus in CW500. The highest average monthly removal rate of arsenic occurred in August (55.9%–74.5%) and the lowest in November (7.8%–15.5%). The arsenic removal efficiency of each VFCW was positively correlated with temperature (P<0.05). Arsenic accumulated in both substrates and plants, with greater accumulation associated with increased arsenic concentrations in the influent. The maximum accumulated arsenic concentrations in the substrates and plants at the end of the experiment were 4.47 mg/kg and 281.9 mg/kg, respectively, both present in CW500. The translocation factor (TF) of arsenic in the reeds was less than 1, with most of the arsenic accumulating in the roots. The arsenic mass balance indicated that substrate accumulation contributed most to arsenic removal (19.9%–30.4%), with lower levels in plants (3.8%–9.5%). In summary, VFCWs are effective for the treatment of arsenic-containing wastewater.     

Fabrication of GO/PAN Nanofiber Membrane Grafted with Chitosan as Efficient Adsorbent for Dye Removal

Journal of Polymers and the Environment - The adsorption is widely used to remove dyes from wastewater because of its low cost, simple preparation, and environmental friendliness. However, the...