焦化废水处理试验系统出水的生物毒性变化

焦化废水是一种典型的难降解工业废水,组分复杂,生物毒性高,大多采用生物处理联合物化深度处理的工艺,以满足炼焦化学工业的污染排放标准,但其排水安全性仍然令人担忧。为研究工艺排水安全性,选择发光细菌青海弧菌Q67、稀有鮈鲫(Gobiocypris rasus)血红细胞、活性污泥微生物群落为测试生物,研究了焦化废水及各处理阶段出水的急性毒性和遗传毒性变化,进而识别影响生物毒性的水质因子。焦化废水经过序批式生物膜反应器处理后,出水急性毒性比进水下降71%,遗传毒性下降为90%以上的轻度以下损伤,显示生物强化处理对焦化废水生物毒性有良好的去除作用。生物处理出水再经过深度处理后,则表现出不同的毒性变化:活性炭吸附法对生物急性毒性的消除最佳,但遗传毒性较生物处理出水有所升高;臭氧氧化法不仅水质改善效率差,且最终出水的生物急性毒性与遗传毒性均升高;臭氧催化氧化法对水中残留有机物去除效率较高,但也造成出水急性毒性与遗传毒性的升高。各水样对青海弧菌Q67的急性毒性与有机物、氮等水质指标表现出较强相关性,而遗传毒性与水质指标之间的相关性不显著。研究结果可为评价和改进处理工艺、保障水体生态安全提供参考。     

Experimental study on oxidative decomposition of nitrobenzene in aqueous solution by honeycomb ceramic-catalyzed ozonation

The ozonation of nitrobenzene in aqueous solution was carried out in a semi-batch reactor to investigate the degradation efficiency, the effect factors, and the reaction mechanism, where honeycomb ceramic was used as a catalyst. The presence of honeycomb ceramic could improve the degradation rate of nitrobenzene by 15.46% compared to the results of ozonation alone. Under the conditions of this experiment, the degradation rate of honeycomb ceramic-catalyzed ozonation increased by 12.94% with the increase of the amount of catalyst from 1 to 5 blocks. The degradation rates all increased greatly with the increase of temperature and pH of the solution in the processes of honeycomb ceramiccatalyzed ozonation and ozonation alone. But, when the pH of the solution increased to 9.50, the advantage of the honeycomb ceramic-catalyzed ozonation process would be lost. The experimental findings indicated that in the processes of ozonation alone and honeycomb ceramic-catalyzed ozonation, nitrobenzene was primarily oxidized by ·OH free radical in aqueous solution. The adsorption of nitrobenzene was too limited to have an important influence on the degradation rate of nitrobenzene. With the same total dosage of applied ozone, the multiple step addition of ozone showed much higher removal efficiency than that obtained by one step in the two processes.     

Carboxymethyl‐β‐cyclodextrin influence on the solubility and toxicity of substituted indole compounds

The solubilization of eight selected substituted indole compounds (SICs) by carboxymethyl‐β‐cyclodextrin (CMCD) in water is reported. The results show that their solubility was well improved in CMCD aqueous solution, and the stoichiometry of inclusion complex of the studied SICs with CMCD was 1: 1. The acute toxicity to Photobacterium phosphoreum of the investigated SICs in CMCD aqueous solutions was also investigated and was compared with that in water. The results show that the toxicity of five studied SICs decreased while the toxicity of the rest three SICs increased in CMCD aqueous solutions, but neither the increase nor the decrease was significant.     

酸性染料的臭氧降解与中间产物

以酸性金黄G模拟染料废水为研究对象,观察臭氧氧化过程中染料溶液吸光度和TOC的变化,利用离子色谱仪、红外光谱仪和GC/MS对染料的降解过程进行了分析,并用发光细菌法检测了溶液急性毒性的变化,结果表明,臭氧对染料的降解符合一级反应动力学,反应40 min后染料溶液的脱色率达到99.3%,TOC去除率为35.7%;染料分子中的S有97.8%被转化为SO2-4,分子中的仲胺基部分转化成酰胺基,水解后生成NH+4,最终氧化成NO-3,溶液中有草酸产生;溶液在臭氧化前期由于生成了醛类和酚类物质,使急性毒性首先呈上升趋势,25min后随着氧化的深入,溶液毒性开始逐渐下降,     

Ce-MCM-41分子筛用于臭氧氧化对氯苯甲酸的活性评价

通过水热法合成了铈掺杂MCM-41(Ce-MCM-41)介孔分子筛,并将其用于臭氧氧化水中对氯苯甲酸(p-CBA).小角X射线衍射(XRD)、氮气吸附-脱附(BET)、紫外可见漫反射光谱(UV-Vis DRS)、透射电镜(TEM)表征结果表明,铈成功进入MCM-41分子筛骨架,以正四面体形式存在,且Ce-MCM-41保持了纯硅MCM-41有序的介孔结构,具有较高的比表面积;铈的掺杂显著提高MCM-41催化臭氧氧化对氯苯甲酸的活性,反应60 min后,TOC去除率由MCM-41的63%提高到86%(Si/Ce=60),而单独臭氧氧化仅为52%;铈的溶出仅为0.085 mg.L-1,较同样负载量的铈负载Ce/MCM-41的溶出(0.44 mg.L-1)有较大减少.催化剂重复使用3次后仍保持较高的活性,这表明Ce-MCM-41具有较好的活性和稳定性,是一种有前景的臭氧氧化催化剂.     

溶解性有机碳的主要组成对青鳉鱼铜急性毒性的影响

为揭示溶解性有机碳(DOC)的组成对生物配体模型(BLM)预测铜的生物毒性准确性的影响,研究了不同浓度黄腐酸(FA)、腐殖酸(HA)和两者不同浓度比例混合物影响铜对青鳉急性毒性。结果表明:在相同水质条件下,黄腐酸或腐殖酸浓度增加时,铜对青鳉的LC50均增加;两者共存时,当腐殖酸质量百分比从10%增至90%时,铜对青鳉的LC50也增加。当天然水中DOC的组成不确定时,可假设HA和FA的组成比例为1∶1,此时BLM预测铜对青鳉的LC50的偏差最小。     

全氟辛烷磺酸盐(PFOS)替代品对中国白羽鹌鹑的毒性

为研究全氟辛烷磺酸盐(perfluorooctane sulfonate,PFOS)替代品对环境生物的毒害效应,选用中国白羽鹌鹑作为受试生物,建立其环境危害评价毒性测试方法,并对PFOS替代化学品进行了急性经口、急性饲喂及繁殖毒性的风险评价。结果表明,全氟丁基有机铵盐阳离子表面活性剂急性经口毒性实验的LD50为500.44mg·kg-1,其余3种替代化学品在上限浓度2000mg·kg-1,白羽鹌鹑均未出现明显死亡,4种PFOS替代品对中国白羽鹌鹑的急性经口毒性均为低毒。全氟丁基有机铵盐阳离子表面活性剂急性饲喂毒性实验的LC50为970.50mg.kg-1,对白羽鹌鹑的饲喂毒性为中毒,而其余3种替代化学品在上限浓度5000mg·kg-1,白羽鹌鹑均未出现明显死亡,对中国白羽鹌鹑的急性饲喂毒性为低毒。在长期饲喂过程中,织物三防整理剂和C6织物三防整理剂会表现出一定的生殖毒性,造成中国白羽鹌鹑的孵化率降低,胚胎死亡率及未受精率升高;全氟丁基有机铵盐阳离子表面活性剂会影响到中国白羽鹌鹑的未受精率,C4织物三防整理剂未表现出明显的生殖毒性。     

城市污水二级硝化出水的离子交换脱氮除磷

以城市污水二级硝化出水为原水,对比研究了3种强碱性阴离子交换树脂(201×4、D296、D301T)动态脱氮除磷情况,并以201×4树脂为模式树脂考察了树脂活化方式(常规酸碱交替活化与NaCl再生液活化)、腐殖酸(HA)浓度(1.1,2.8和9.4 mg·l~(-1))对树脂动态脱氮除磷的影响.结果表明,3种树脂都具有较好的脱氮除磷效果,达到TP穿透点(0.1 mg·l~(-1),去除率92%)时,201×4树脂具有最大的穿透体积(418 BV),但其对NO_3~--N的去除率(69%)明显低于其它树脂(97%-98%);3种树脂对SO_4~(2-)和HA的去除率分别为97%-99%,71%-80%;常规酸碱活化使树脂穿透体积较再生液活化仅提高了12%;超滤膜法和臭氧氧化法预处理对原水HA的去除率分别为27%和68%;原水HA浓度增加使树脂穿透体积从28lBV降至239BV,同时NO_3~-去除率从80%上升至92%.     

全氟辛烷磺酸盐(PFOS)替代品对中国白羽鹌鹑的生态毒性

为研究全氟辛烷磺酸盐(perfluorooctane sulfonate,PFOS)替代品对环境生物的毒害效应,选用中国白羽鹌鹑作为受试生物,建立其环境危害评价毒性测试方法,并对PFOS替代化学品进行了急性经口、急性饲喂及繁殖毒性的风险评价。结果表明,全氟丁基有机铵盐阳离子表面活性剂急性经口毒性实验的LD50为500.44mg·kg-1,其余3种替代化学品在上限浓度2000mg·kg-1,白羽鹌鹑均未出现明显死亡,4种PFOS替代品对中国白羽鹌鹑的急性经口毒性均为低毒。全氟丁基有机铵盐阳离子表面活性剂急性饲喂毒性实验的LC50为970.50mg.kg-1,对白羽鹌鹑的饲喂毒性为中毒,而其余3种替代化学品在上限浓度5000mg·kg-1,白羽鹌鹑均未出现明显死亡,对中国白羽鹌鹑的急性饲喂毒性为低毒。在长期饲喂过程中,织物三防整理剂和C6织物三防整理剂会表现出一定的生殖毒性,造成中国白羽鹌鹑的孵化率降低,胚胎死亡率及未受精率升高;全氟丁基有机铵盐阳离子表面活性剂会影响到中国白羽鹌鹑的未受精率,C4织物三防整理剂未表现出明显的生殖毒性。     

Utility of the QSAR modeling system for predicting the toxicity of substances on the European inventory of existing commercial chemicals∗

Many chemicals are in common commercial use for which no information on the environmental fate or toxicity exists. Recent legislation requires that many substances be assessed for their toxicity to aquatic organisms within a very short time and determine which of these chemicals need to be studied in greater detail. It would be impossible to measure the acute and chronic effects of all of these compounds on a single organism, let alone a battery of different types of organisms, communities or ecosystems. Initially, the chemicals on the European Inventory of Existing Commercial Chemical Substances (EINECS) need to be screened and relative hazard to the environment determined. In response to OECD directives, there has been a great deal of activity by government and industry scientists. At the International Workshop on Advances in Environmental Hazard and Risk Assessment it was concluded that quantitative structure activity relationships (QSAR) could and should be used in the hazard assessment process. Papers published in that volume outline the advantages, disadvantages, limitations, advances and research requirements.

The QSAR, structure‐activity based chemical modeling and information system, which was developed by the US‐Environmental Protection Agency was used to predict the acute toxicity of 113 substances from the “Old Substances”; list of the German government to the four commonly used aquatic toxicity test organisms: Daphnia magna (DM), fathead minnow (FHM), rainbow trout (RBT), and blue‐gill sunfish (BG).

Of these compounds the QSAR system predicted the acute toxicity of 87 substances towards fathead minnow. For the other three species examined the QSAR system could be used to predict toxicity for 78 compounds.

The predicted toxicities were compared to observed toxicities of compounds which have been evaluated and stored in the “Aquire”; data base. Observed toxicity values were available for at least one species for 38 compounds. The toxicities of some compounds are well predicted while those of other compounds were not well predicted. Overall, the QSAR system accurately classified the acute toxicity ranges of 50%, 64%, 56% and 56% of the compounds investigated for DM, FHM, RBT and BG, respectively. Of the compounds studied 10 were very poorly predicted, of these the QSAR system overpredicted the toxicity of three, while underpredicting the toxicity of seven. Of these seven compounds, five contained amino groups.     

不同分子量的腐殖酸存在下2种无机砷的生物毒性效应研究

水环境中天然有机质会与砷形成络合物,进而影响砷的迁移、转化和生物毒性。研究利用超滤方法将腐殖酸(humic acid, HA)分为5个不同分子量的组分,以大型溞为受试生物,探究了不同分子量HA存在下砷对大型溞的毒性效应。结果表明,不同分子量的HA均缓解了As(Ⅲ)和As(Ⅴ)对大型溞的氧化应激损伤和细胞膜损伤,并降低了砷对MT的诱导量。其中1～30 k Da的HA对砷的缓解效果最好,1 k Da的HA毒性缓解效果最差,可能的原因是HA与砷的络合增加溶液中络合态砷的含量,而络合态砷难以进入细胞并被生物利用。不同分子量的HA对砷毒性的缓解差异与其跟砷的络合比例不同有关。     

腐殖酸对As(V)在覆铁砂介质中吸附行为的影响

对腐殖酸(HA)进行了成分分析及红外表征,并从HA浓度、pH值、As(Ⅴ)初始浓度等方面,研究了HA对As(Ⅴ)在覆铁砂介质中吸附行为的影响.结果表明,随着HA浓度的升高,总砷去除率逐渐降低.当HA浓度增加到25mg.l-1时,与不存在HA条件下相比,总砷去除率降低了12%左右.溶液pH值影响As(Ⅴ)的去除,pH值从6升高到8时,总砷去除率从52.1%降到了39%.其中的作用机理主要是HA与As(Ⅴ)在覆铁砂表面形成竞争吸附,HA争夺了As(Ⅴ)的吸附点位.此外,HA与Fe(Ⅲ)的络合作用也是导致覆铁砂对砷的去除率降低的一个重要原因.     

Bisphenol A endocrine disruptor complete degradation using TiO2 photocatalysis with ozone

Bisphenol A is an endocrine disruptor. Complete mineralization of bisphenol A is therefore a primary environmental issue. Here, the combination of ozonation and photocatalysis by TiO₂ is proposed for the degradation and final mineralization of bisphenol A. TiO₂ films deposited onto two sides of an Al lamina show good stability and high surface roughness. We used a specific experimental setup employing two facing ultraviolet lamps and TiO₂ layers, together with an ozone flux. High-performance liquid chromatography–mass spectrometry determinations on bisphenol A solutions sampled at different reaction times and Fourier Transform Infrared analyses of the oxide at the end of the reaction were performed to study the reaction intermediates and the overall degradation mechanism. Our results show that pollutant mineralization achieved with the combined method is far higher, of 55% in the case of 0.3 mM bisphenol A, than those obtained by individual treatments such as photolysis (<3%), ozonation (6%), photocatalysis (6%), and by other combined processes: photolytic ozonation (13%) and catalytic ozonation (15%). This finding is explained by the occurrence of highly synergistic effects.     

助溶剂甲苯和二甲基亚砜对斑马鱼胚胎发育的复合毒性效应

研究了甲苯和二甲基亚砜(DMSO)对斑马鱼胚胎生长、发育的毒性效应.实验结果表明:低剂量的甲苯(0.05%)单一暴露对斑马鱼胚胎发育有一定毒性,DMSO(0.45%)对斑马鱼胚胎无明显毒性;但甲苯与DMSO具有较强的复合毒性效应,随着DMSO含量的增加,与甲苯单一暴露组相比,斑马鱼胚胎死亡率显著增加、胚胎孵化率下降、胚胎发育迟缓并生成大量畸形;但甲苯以及甲苯和DMSO复合物对人胚肾HEK-293细胞株和人胃癌SGC-7901细胞株的活力均没有明显效应.DMSO可通过提高甲苯在水中的分散性,增加甲苯的神经毒性,但对离体实验模型无显著效应,故在选择不同生物模型评估有机污染物毒性效应时,需考虑不同类型助溶剂所产生的复合效应,以减少实验误差.     

Catalytic ozonation of reactive red X-3B in aqueous solution under low pressure: decolorization and OH· generation

Catalytic ozonation of Reactive Red X-3B in aqueous solution had been carried out in an ozone oxidation reactor where Mn-Fe-ceramic honeycomb was used as the catalysts. The presence of Mn-Fe-ceramic honeycomb catalyst could obviously improve the decoloration efficiency of Reactive Red X-3B and the utilization efficiency of ozone compared to the results from non-catalytic ozonation. Adsorption of Reactive Red X-3B had no obviously influence on the degradation efficiency. Addition of tert-butanol significantly decreased the degradation efficiency, indicating that the degradation of Reactive Red X-3B followed the mechanism of hydroxyl radical (OH·) oxidation. The operating variables such as reaction pressure and ozone supply had a positive influence on the degradation efficiency, mainly attributing to facilitate the ozone decomposition and OH· formation.     

酚类化合物臭氧氧化速率的神经网络研究

酚类化合物(BP)是重要的工业原料或中间体,但工业废水含有的酚类化合物会对环境造成污染。为建立酚类化合物臭氧氧化速率的QSPR(quantitative structure-property relationship)预测模型,分析了23种酚的分子结构与臭氧氧化速率之间的相关关系,计算了这些酚的分子连接性指数和分子形状指数,优化筛选了连接性指数的1χ和2χ、分子形状指数的K1和K2共4种参数,将其作为BP神经网络的输入层变量,臭氧氧化速率作为输出层变量,采用4:2:1的网络结构,获得了令人满意的QSPR神经网络预测模型,模型总相关系数r为0.976,计算得到的臭氧氧化速率的预测值与实验值较为吻合,平均残差仅为0.05;为检验结构参数建立模型的普适性,同样方法建立对酚类化合物的辛醇-水分配系数的预测模型,模型总相关系数r达到0.993,辛醇-水分配系数的预测值与实验值吻合度较为理想,结果表明,本法建构的神经网络模型具有良好的稳健性和预测能力。     

Ozonation as an efficient pretreatment method to alleviate reverse osmosis membrane fouling caused by complexes of humic acid and calcium ion

Humic acids (HA) didn’t cause obvious reverse osmosis (RO) membrane fouling in 45 h. Osmotic pressure (NaCl) affected slightly the RO membrane fouling behavior of HA. Ca²⁺ promoted aggregation of HA molecules and thus aggravated RO membrane fouling. Ozonation eliminated the effect of Ca²⁺ on the RO membrane fouling behavior of HA. The change of the structure of HA was related to its membrane fouling behavior. Humic acid has been considered as one of the most significant sources in feed water causing organic fouling of reverse osmosis (RO) membranes, but the relationship between the fouling behavior of humic acid and the change of its molecular structure has not been well developed yet. In this study, the RO membrane fouling behavior of humic acid was studied systematically with ozonation as a pretreatment method to control RO membrane fouling. Furthermore, the effect of ozone on the structure of humic acid was also explored to reveal the mechanisms. Humic acid alone (10–90 mg/L, in deionized water) was found not to cause obvious RO membrane fouling in 45-h operation. However, the presence of Ca²⁺ aggravated significantly the RO membrane fouling caused by humic acid, with significant flux reduction and denser fouling layer on RO membrane, as it was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). However, after the pretreatment by ozone, the influence of Ca²⁺ was almost eliminated. Further analysis revealed that the addition of Ca²⁺ increased the particle size of humic acid solution significantly, while ozonation reduced the SUVA₂₅₄, particle size and molecular weight of the complexes of humic acid and Ca²⁺ (HA-Ca²⁺ complexes). According to these results and literature, the bridge effect of Ca²⁺ aggregating humic acid molecules and the cleavage effect of ozone breaking HA-Ca²⁺ complexes were summarized. The change of the structure of humic acid under the effect of Ca²⁺ and ozone is closely related to the change of its membrane fouling behavior.     

Kinetic studies of the degradation of parabens in aqueous solution by ozone oxidation

Ozone degradation of a mixture containing methylparaben, ethylparaben, propylparaben, butylparaben and benzylparaben was carried out in aqueous solution. The degradation followed the pseudo-first-order kinetic model and occurs with two ozonation stages with the observed rate constants of second stage ozonation, k _obs2, being higher than the observed rate constants in first stage, k _obs1. The k _obs1 of parabens was found to increase exponentially whilst k _obs2 was found to maximize at 35°C. Both k _obs1 and k _obs2 were found to decrease exponentially with respect to the initial concentration of parabens. Both pH and ozone dose showed positive effects on the rate of degradation. It was also observed that an ozone dose of 0.67 g/h resulted in the removal of 99% of parabens in 12 min, and also the removal of 61 and 32% of chemical oxygen demand (COD) and total organic carbon (TOC), respectively, in 3 h of ozonation time for a 500 μM of solution of parabens.     

水环境中天然有机物对纳米颗粒吸附铅和镉的不同作用

为阐明天然有机物(NOM)在纳米颗粒(NPs)吸附重金属中的作用,研究了蛋白质(牛血清白蛋白,BSA)、碳水化合物(海藻酸钠,NaAlg)和腐殖酸(HA)对二氧化钛纳米颗粒(TNPs)和氧化铈纳米颗粒(CNPs)聚集沉降和吸附Cd²⁺和Pb²⁺的影响.结果表明,当Pb²⁺和Cd²⁺在20—120 mg·L-1范围内,HA和NaAlg显著促进了TNPs和CNPs对这些金属离子的吸附(P<0.05),而BSA对这些金属吸附的影响甚微.TNPs-HA和TNPs-NaAlg对Pb²⁺的吸附分别提高了14%—41%和16%—57%,对Cd²⁺的吸附分别提高了12%—112%和22%—143%.与CNPs相比,CNPs-HA和CNPs-NaAlg对Pb²⁺的吸附增加了21%—71%和23%—65%,对Cd²⁺的吸附增加了26%—45%和45%—91%.并且NPs和NPs-NOM对Pb²⁺和Cd²⁺的吸附符合Freundlich吸附模型.离子强度的增加抑制了NPs-HA/NaAlg和NPs对Pb²⁺和Cd²⁺的吸附,而pH的增加对NPs-HA/NaAlg和NPs吸附Pb²⁺和Cd²⁺起促进作用.     

臭氧污泥减量过程中混合液各参数的变化

实验用污泥的初始浓度(MLSS)分别限定为4g/L、7g/L和11g/L,用以探讨不同浓度下臭氧氧化过程中COD、N和P浓度的变化。结果表明:臭氧氧化过程中,MLSS和MLVSS基本呈线性下降;臭氧对污泥细胞的溶解可以引起混合液中COD、N和P浓度的升高,升高速率受污泥浓度和臭氧浓度影响较大;TKN和硝态氮是N的主要存在形式,TKN和TN随时间均呈先增加后趋缓的变化规律;臭氧对氨氮和亚硝酸盐氮有较强的氧化能力,二者浓度均呈先增大后减小的规律;而硝酸盐氮呈一直增加趋势;臭氧对COD的氧化也很明显,表现为COD的增加速率随氧化时间的增加而不断降低;总磷的浓度基本呈线性增加,单位质量污泥的总磷释放量差异不大;臭氧对MLSS的彻底减量会引起臭氧溶胞利用率的降低,因此应该合理控制臭氧化反应的时间。