铁碳微电解人工湿地对典型有机磷阻燃剂的去除研究

Study on the removal of typical organophosphate flame retardants by iron-carbon micro-electrolysis constructed wetlands

  • 摘要: 针对传统人工湿地(CWs)对有机磷阻燃剂(OPFRs)去除效能不足的问题,本研究构建了铁碳微电解(ICME)强化CWs系统。选取生物炭-海绵铁(BC+SI)、活性炭-铁屑(AC+Fe)及商品铁碳材料(FeC)三种填料组合,系统考察了不同填料、水力停留时间(0.5~2 d)及进水OPFRs负荷(300~1500 μg/L)对磷酸三苯酯(TPHP)、磷酸三(2-氯乙基)酯(TCEP)和磷酸三(氯丙基)酯(TCPP)三种典型OPFRs去除的影响。结果表明:BC+SI组合的去除效能最优,对TPHP、TCEP和TCPP的平均去除率均超过95%。出水中COD、TN和TP的平均去除率最高分别达85.5%、75.5%和93.6%,出水水质优于《城镇污水处理厂污染物排放标准》一级A标准。ICME填料的加入显著改变了CWs微环境,出水pH值升至8.0~8.5,强化层溶解氧降至0.3~0.9 mg/L,为污染物降解创造了有利条件。水力停留时间(HRT)从2 d缩短至0.5 d或进水OPFRs浓度增至1500 μg/L时,OPFRs去除率分别下降约30%和35%。BC+SI组合通过吸附与微电解的协同作用,能高效稳定地去除水中典型OPFRs及常规污染物。

     

    Abstract: To address the limited removal efficiency of conventional constructed wetlands for organophosphate flame retardants (OPFRs), this study developed intensified constructed wetland systems by incorporating iron-carbon micro-electrolysis (ICME) substrates. Three substrate combinations, biochar-sponge iron (BC+SI), activated carbon-iron filings (AC+Fe), and a commercial iron-carbon material (FeC), were evaluated for their performance in removing three typical OPFRs—triphenyl phosphate (TPHP), tris(2-chloroethyl) phosphate (TCEP), and tris(chloropropyl) phosphate (TCPP). The effects of different substrates, hydraulic retention times (HRT, 0.5-2 d), and influent OPFR concentrations (300-1500 μg/L) on removal efficiencies were systematically investigated. The results showed that the BC+SI combination achieved the highest performance, with average removal rates exceeding 95% for all three OPFRs. The system also demonstrated excellent removal of conventional pollutants, with maximum average removal rates of 85.5% for COD, 75.5% for TN, and 93.6% for TP, meeting the Grade 1 A standard of China's Discharge Standard for Pollutants from Municipal Wastewater Treatment Plants. Mechanism analysis revealed that the ICME substrates significantly altered the system's microenvironment, increasing the effluent pH to 8.0-8.5 and decreasing the dissolved oxygen in the intensified layer to 0.3-0.9 mg/L, thereby creating favorable conditions for pollutant degradation. Shortening the HRT from 2 d to 0.5 d or increasing the influent OPFR concentration to 1500 μg/L reduced OPFR removal rates by approximately 30% and 35%, respectively. This study concludes that the BC+SI combination, through the synergistic effects of adsorption and micro-electrolysis, provides an efficient and stable method for removing both typical OPFRs and conventional pollutants from water.

     

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