利用零价铁去除挥发性氯代脂肪烃的试验

选用四氯乙烯(PCE)、三氯乙烯(TCF)与四氯化碳(CT)为靶污染物,研究不同组合下,零价铁系统对各污染物降解的有效性及反应进行的影响因素.结果表明:实验选用的废料生铁可有效去除水中的有机氯代脂肪烃类,尤其对氯代烷烃具有较强的降解功能,且反应符合准一级反应动力学方程;当PCE和TCE共存时,PCE和TCE的反应速率常数K分别为0.0624mL·(m²·h)^-1和0.0357mL·(m²·h),说明氯代程度高的PCE脱氯快;当CT和PCE共存时,二者的K分别为0.1341mL·(m2·h)^-1和0.0129mL·(m²·h)^-1,CT的脱氯快且彻底,说明氯代程度相同时烷烃的脱氯优于烯烃;无论是哪种氯代烃,单独存在时其反应的半衰期均短于与其它组分共存时.  

碱性系统中铁对铬的还原作用及其对飞灰中铬的浸出控制

为了控制焚烧飞灰中铬的浸出,将FeSO4加入焚烧飞灰-水系统中和Cr（Ⅵ）的碱性水溶液中,试验二价铁（Fe（Ⅱ））对Cr（Ⅵ）的还原效果,并检验了Cr（Ⅵ）的还原产物的稳定性.热力学分析表明,碱性系统中Fe（Ⅱ）对Cr（Ⅵ）的还原受到Fe（Ⅱ）与O2反应的强烈竞争.实验结果也证实了暴露于空气的飞灰-水系统中的Fe（Ⅱ）对铬没有明显的控制效果,但在碱性溶液相中过量的Fe（Ⅱ）却能快速有效地还原Cr（Ⅵ）,且还原产物十分稳定.此外,焚烧飞灰中铬的溶出受到Pb、Ba、Ca等元素的干扰,不利于Cr（Ⅵ）的还原稳定.为了有效地稳定Cr（Ⅵ）,Fe（Ⅱ）稳定飞灰的过程可分两步进行.试验结果还表明,在碱性系统中铁的氧化物/氢氧化物对Cr（Ⅵ）的吸附和沉淀效果十分有限.  

淹水厌氧条件下腐殖酸对红壤中铁异化还原过程的影响

采用室内培养实验，观测淹水厌氧条件下分别添加及共同添加葡萄糖和不同制备来源的腐殖酸，对红壤中铁的异化还原作用的影响.结果表明，红壤单独培养条件下，Fe(Ⅱ)浓度培养前后没有发生变化.添加葡萄糖促进了铁的异化还原，培养至12 d其Fe(Ⅱ)浓度为培养前的25倍.腐殖酸不能作为电子供体促进铁的异化还原，单独添加时红壤中Fe(Ⅱ)浓度没有发生变化，而同时添加葡萄糖情况下，培养前期促进而后期减弱铁的异化还原，其Fe(Ⅱ)浓度增幅仅为单独添加葡萄糖处理的35%.腐殖酸的浓度对红壤中铁的异化还原作用有影响，浓度为2.00 g/kg时培养前期促进而后期减弱铁的异化还原，低浓度时（0.20和0.02 g/kg）影响很小.不同制备来源的腐殖酸对红壤中铁异化还原过程的影响不同.培养前期，从山西大同风化煤(HAs)、河南巩县褐煤(HAh)和云南昆明滇池底泥(HAk)中提取的腐殖酸都促进了红壤中铁的异化还原；培养后期，HAk依然发挥促进作用，其Fe(Ⅱ)浓度始终高于G处理，而添加HAs和HAh的处理培养至7 d Fe(Ⅱ)仅为单独添加葡萄糖处理的14%和25%，减弱了铁的异化还原.  

Anaerobic biodegradation of benzene series compounds by mixed cultures based on optional electronic acceptors

A series of batch experiments were performed using mixed bacterial consortia to investigate biodegradation performance of benzene, toluene, ethylbenzene and three xylene isomers （BTEX） under nitrate, sulfate and ferric iron reducing conditions. The results showed that toluene, ethylbenzene, m-xylene and o-xylene could be degraded independently by the mixed cultures coupled to nitrate, sulfate and ferric iron reduction. Under ferric iron reducing conditions the biodegradation of benzene and p-xylene could be occurred only in the presence of other alkylbenzenes. Alkylbenzenes can serve as the primary subs＇rates to stimulate the transformation of benzene and p-xylene under anaerobic conditions. Benzene and p-xylene are more toxic than toluene and ethylbenzene, under the three terminal electron acceptors conditions, the degradation rates decreased with toluene 〉 ethylbenzene 〉 m-xylene 〉 o-xylene〉 benzene 〉 p- xylene. Nitrate was a more favorable electron acceptor compared to sulfate and ferric iron. The ratio between sulfate consumed and the loss of benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene was 4.44, 4.51, 4.42, 4.32, 4.37 and 4.23, respectively; the ratio between nitrate consumed and the loss of these substrates was 7.53, 6.24, 6.49, 7.28, 7.81, 7.61, respectively; the ratio between the consumption of ferric iron and the loss of toluene, ethylbenzene, o-xylene, m-xylene was 17.99, 18.04, 18.07, 17.97, respectively.  

微生物-铁氧化物交互作用对黄土中砷活化迁移的影响

中国黄土高原地区普遍存在地下水砷超过饮用水标准问题,迫切需要深入认识和理解高砷地下水形成机制.在分析黄土中砷的含量、赋存状态基础上,以乳酸钠为有机碳源,开展缺氧条件下厌氧微生物-铁氧化物交互作用影响黄土中砷活化迁移的模拟实验研究.结果表明黄土中砷含量在23~30 mg·kg-1,变化范围很小.砷主要以吸附态、铁氧化物结合态、残渣态形式存在,平均值分别为10.57 mg·kg-1(占总砷37.76%)、10.12 mg·kg-1(占总砷36.15%)、7.19 mg·kg-1(占总砷25.69%);当水中存在有机物形成缺氧环境时,厌氧微生物异化铁还原菌(DIRB)和硫酸盐还原菌(SRB)直接或间接还原铁氧化物引起部分铁氧化物分解,导致吸附态和铁氧化物结合态砷部分释放到地下水中,引起地下水中砷升高,砷释放量主要与水中有机物浓度有关.研究表明,当有机物浓度达到100 mg·L-1时,固液比为1∶10,在土著微生物作用下,砷浓度可以达到15μg·L-1;接种DIRB和SRB以及两种微生物同时存在都有明显的促进黄土中砷活化迁移的作用,水中砷浓度可以达到40μg·L-1.  

零价铁去除三氯乙烯及四氯乙烯对比实验研究

文章以三氯乙烯(TCE)和四氯乙烯(PCE)为目标污染物,采用批实验方法,研究零价铁的纯度、粒径、投加量对零价铁去除氯代烃的影响,同时分析TCE、PCE两种污染物共存对零价铁去除TCE和PCE的影响。实验结果表明:(1)在实验范围内,零价铁的纯度越高,粒径越小,投加量越大,零价铁对TCE和PCE的去除效果越好;(2)零价铁对四氯乙烯的去除效果比对三氯乙烯的去除效果好;(3)三氯乙烯、四氯乙烯共存时会相互竞争与零价铁的反应位点,从而降低各组分的去除效率。  

铁还原中和沉淀法处理TNT酸性废水的研究

研究了处理TNT酸性废水的铁还原中和方法。该法用铁将硝基苯类还原成苯胺类，然后通过石灰乳中和生成Fe(OH)2胶体，吸附苯胺类，达到去除硝基苯类的目的。在过量铁还原60min，中和沉淀pH8—9的最佳条件下，可将废水中的硝基苯类从82．0mg/L降到未检出程度(＜0．2mg/L)，CODcr从394．0mg/L降到94．8mg/L。处理后的废水中的苯胺类也未检出(＜0．03mg/L)。该法的物料消耗费用约为传统的活性碳吸附法的17．5％。  

Remediation of Ni2+-contaminated water using iron powder and steel manufacturing byproducts

Steel manufacturing byproducts and commercial iron powders were tested in the treatment of Ni^2＋-contaminated water. Ni^2＋ is a priority pollutant of some soils and groundwater. The use of zero-valent iron, which can reduce Ni^2＋ to its neural form appears to be an alternative approach for the remediation of Ni^2＋-contaminated sites. Our experimental data show that the removal efficiencies of Ni^2＋ were 95.15% and 94.68% at a metal to solution ratio of 20 g/L for commercial iron powders and the steel manufacturing byproducts in 60 min at room temperature, respectively. The removal efficiency reached 98.20% when the metal to solution ratio was 40 g/L for commercial iron powders. Furthermore, we found that the removal efficiency was also largely affected by other factors such as the pHs of the treated water, the length of time for the metal to be in contact with the Ni^2＋-contaminated water, initial concentrations of metal solutions, particle sizes and the amount of iron powders. Surprisingly, the reaction temperature appeared to have little effect on the removal efficiency. Our study opens the way to further optimize the reaction conditions of in situ remediation of Ni^2＋ or other heavy metals on contaminated sites.  

Shewanella oneidensis MR-1异化还原Fe（III）介导的As（III）氧化转化

在实验室模拟条件下,研究了Shewanella oneidensis MR-1作用下Fe(III)还原和As(III)氧化动力学及其影响因素.结果表明,Fe(III)被还原为 Fe(II)的同时伴随着 As(III)氧化为 As(V)；S. oneidensis MR-1在含低浓度 As(III)培养基上生长良好,在高浓度培养基上生长被抑制；As(III)通过制约菌体的生长与活性来抑制 Fe(III)异化还原.同样,适量浓度的 Fe(III)含量对 As(III)氧化转化有很强的促进作用,但是过高浓度的Fe(III)浓度使得溶液中产生过多的Fe(II),从而对As(III)氧化转化有一定程度的抑制作用.此外,弱碱环境更有利于As(III)氧化转化.  

零价铁还原和吸附去除水中污染物的研究进展

近年来,零价铁以其低毒、廉价、易操作且对环境不会产生二次污染等优点,在水污染治理中受到重视。文章介绍了零价铁处理污水的机理,对利用零价铁的还原和吸附作用去除污水中的氯代有机物、硝基芳香族化合物、偶氮染料、重金属、高氯酸盐、硝酸盐等的研究情况进行了综述,指出了零价铁废水处理技术的研究方向。