抗生素类污染物对活性污泥生物毒性测定方法的筛选与评价

尽管衡量化学物质生物毒性的标准方法很多,但关于环境中抗生素类污染物的生物毒性及其对污泥活性影响的科学数据较少。以磺胺和四环素两类作用机理和作用谱带不同的抗生素为研究对象,分别用发光细菌法、脱氢酶活性法、生长抑制法及呼吸速率法进行了抗生素类污染物生物毒性测定方法的筛选与评价。结果表明,发光细菌标准方法中30min的作用时间太短,延长作用时间不仅导致各种抗生素的EC50值大幅度降低,同时毒性排列顺序也发生了改变;以活性污泥为对象的脱氢酶活性和呼吸速率抑制实验的EC50值与抗生素类物质对敏感致病菌的MICs相比异常高,不适宜于作为单独方法准确评估抗生素类污染物的生物毒性。生长抑制实验中,活性污泥混合菌种增殖生长对磺胺类抗生素敏感,而假单胞杆菌对四环素类抗生素敏感。不同方法测定抗生素毒性的灵敏度顺序是发光细菌(24 h)>生长抑制(7 h)>呼吸速率(24 h)>脱氢酶活性(24 h)。用标准方法评价抗生素类污染物的生物毒性,可能导致对抗生素排放到水环境中所带来的风险估计不足。     

氧化锌纳米颗粒对SBR中活性污泥脱氮性能及硝化细菌丰度的影响

在SBR中添加氧化锌纳米颗粒(ZnO-NPs),研究ZnO-NPs对活性污泥脱氮性能及硝化细菌丰度的影响。结果表明,低浓度(1 mg·L~(-1))ZnO-NPs对活性污泥脱氮性能无影响,高浓度(10、50 mg·L~(-1))ZnO-NPs可抑制活性污泥硝化性能,且对硝化菌活性抑制作用小于亚硝化菌。ZnO-NPs浓度梯度增加至50 mg·L~(-1)较直接投加50 mg·L~(-1)ZnO-NPs对污泥活性抑制作用小。高浓度ZnO-NPs改变活性污泥微生物胞外聚合物(EPS)产量和性质。SBR运行结束时,高浓度ZnONPs的添加导致亚硝化菌相对丰度大幅度减小,而对硝化菌相对丰度影响较小。     

反硝化聚磷一体化设备中的聚磷菌

研究了新型生物脱氮除磷新工艺反硝化聚磷一体化设备中反硝化厌氧池活性污泥的兼性厌氧微生物组成，数量及其在该除磷系统中功能，结果表明，稳定运行期反硝化厌氧池内活性污泥混合液的兼性厌氧微生物总数大大多于启动期，稳定期和启动期分离的兼性厌氧微生物有假单胞菌属，副球菌属和肠杆菌科，通过对三种纯菌株进行吸放磷研究，三种菌都有不同程度的聚磷功能，说明反硝化菌也具有聚磷作用。     

苯酚对活性污泥硝化与反硝化动力学的影响

通过批次试验,研究苯酚与活性污泥缺氧和好氧接触对微生物硝化和反硝化作用的影响。结果表明:(1)苯酚对缺氧2h后的活性污泥硝化有抑制作用,且苯酚浓度越高,抑制作用越强。当苯酚浓度较低时对自养菌的最大比氨氧化速率(AUR)的抑制作用能用竞争性抑制Monod方程拟合,半数抑制质量浓度(IC50)为19.2mg/L。(2)苯酚对直接曝气的活性污泥比对缺氧接触2h后再曝气的活性污泥的硝化抑制作用更强,当苯酚从0mg/L增加到10.0mg/L,AUR由2.51mg/(L·h)降至0.36mg/(L·h),且在10.0mg/L时,硝化抑制率(IR)高达85.7%。(3)苯酚的抑制效应随着缺氧时间延长而逐渐降低。当苯酚为10.0mg/L时,直接曝气的活性污泥受到的硝化抑制最强,IR为85.8%,并在缺氧4h后IR降为0。(4)当碳源充足时,活性污泥的反硝化菌对苯酚的耐受力较强,苯酚对活性污泥的反硝化过程没有影响,微生物的反硝化速率(NUR)维持在5.279～5.308mmol/(mg·h)。     

混合重金属对硝化颗粒污泥毒性作用的析因实验研究

分别测定了Cu2 、Zn2 和Cd2 对硝化颗粒污泥的单一毒性,采用析因实验研究了二元和三元重金属混合体系对硝化颗粒污泥的联合毒性.结果表明,Cu2 、Zn2 和Cd2 的2 h半抑制浓度EC50分别为95.23、62.11和12.48 mg/L,由析因实验所得的响应曲面模型具有较好的优度(其R2＞0.95),能够对混合体系的联合毒性很好地进行预测,析因实验可以用于环境领域混合体系联合毒性的研究.     

Cu~(2+)、Zn~(2+)对生物脱氮系统的影响

Cu2+和Zn2+是污水处理工艺中经常遇到的金属离子.在驯化好的活性污泥系统中,研究了金属离子Cu2+和Zn2+在0～100 mg/L浓度下对活性污泥牛物脱氮系统的影响.试验发现Cu2+＞5 mg/L、Zn2+＞30 ms/L时,对硝化过程具有明显的抑制作用,在同样浓度的试验条件下Cu2+对硝化过程的抑制作用比Zn2+大.Cu2+≤0.5 mg/L时对反硝化过程具有一定的促进作用,有助于提高TN的去除效果;Cu2+＞0.5 mg/L时,对反硝化产牛抑制作用,随着浓度的增加,TN去除率逐渐下降.Zn2+不影响反硝化过程,仅在大于30 mg/L时,对硝化过程产生抑制作用.重金属Cu2+对生物脱氮系统的影响明显强于Zn2+.     

盐度对活性污泥驯化前后硝化特性的影响

通过批量试验系统研究了盐度对常规活性污泥硝化作用的影响以及污泥在含盐环境中经过驯化后其硝化功能的变化.试验结果表明,硝化菌比亚硝化菌对盐度更敏感,废水中含盐浓度为5 g/L时,对常规活性污泥中的亚硝化菌影响不大,硝化菌会受到一定程度的抑制;当含盐浓度超过10 g/L时,硝化菌和亚硝化菌均会受到严重抑制;含盐浓度大于30 g/L时,亚硝化菌和硝化菌已经完全受到抑制.在污泥驯化初期,耐盐硝化菌群数量较少,比硝化速率较低,硝化产物中亚硝态氮大量积累;随着驯化时间的延长,耐盐硝化菌群数量增加,比硝化速率增加,亚硝态氮累积量减少.污泥经过驯化后,硝化菌群可以逐渐适应高盐环境,在含盐浓度为30 g/L时硝化反应仍能进行.     

毒性微生物传感器的研制及应用

以从土壤中分离、筛选出的X4菌株作为分子识别元件,采用夹层法制备微生物膜并与极谱型氧电极组成了呼吸抑制型毒性微生物传感器。实验确定了传感器的最佳工作条件:温度为30℃,pH范围为7.0~7.5;以HgCl2作为参比毒物时,微生物传感器标准曲线为y=1.05 x+0.21,线性相关系数为0.9933,线性范围为0.1~1.97 mg/L,相对标准偏差为1.8%。用该微生物传感器对某印染废水的毒性进行测试,该废水的毒性相对于HgCl2的浓度为1.69 mg/L,属于剧毒,与发光细菌法进行比对,测定结果具有一致性。     

溶解氧对晚期垃圾渗滤液短程硝化及微生物群落结构变化的影响

以上海老港垃圾填埋场配套污水处理设施中的污泥为菌种源,在序批式活性污泥反应器(SBR)中对晚期垃圾渗滤液进行短程硝化处理,调节SBR中溶解氧浓度,考察溶解氧对渗滤液短程硝化的影响,分析不同溶解氧条件下污泥微生物群落结构的变化.结果表明,低溶解氧(0.2～0.5 mg/L)条件下,SBR可以获得较高的短程硝化效率,反应17h后,SBR内亚硝态氮/氨氮(质量比)为1.05,氨氮负荷可达到1.5 kg/(kg·d)(以每千克污泥悬浮固体每天承担的氨氮计),出水可以满足后续厌氧氨氧化处理的要求.从污泥变形梯度凝胶电泳(DGGE)图谱中可以看出,SBR微生物群落结构中主要优势种有uncultured Bacteroidetes bacterium、uncultured bacterium、uncultured Candidatus Amoebophilus sp.等.随着溶解氧含量的升高,SBR内微生物群落结构的多样性有所升高,但溶解氧对微生物群落结构影响有限.     

SFBR工艺顺序进行硝化和反硝化的动力学研究

采用序半连续式反应器(sequencing fed-batch reactor,简称SFBR)对人工合成废水顺序地进行硝化和反硝化动力学进行了研究.硝化和反硝化所用微生物为活性污泥.反应器在不同的操作条件进行操作,获得了用于确定动力学常数的数据;获得动力学参数um=0.05 h-1,KNO=2.0 mg/L,y=0.47 mg X/mg N,a=0.001 h-1.类似地确定了反硝化动力学参数kD=0.01 h-1和KD,NO=0.4 mg/L.在一定范围内硝化和反硝化速率随着氨浓度和硝酸盐浓度的增加而增加.实验数据表明,硝化和反硝化的动力学符合Monod动力学方程.     

Comparison of bioluminescence and nitrification inhibition methods for assessing toxicity to municipal activated sludge

The aim of this study was to compare two alternative toxicity assessment methods to determine wastewater toxicity and predict treatment plant process upsets. The toxicity of two synthetic organic compounds (triclosan and 4-n-nonylphenol), which are commonly detected in municipal wastewater, and municipal and industrial wastewaters with different heavy metals content were evaluated by the nitrification inhibition assay and bioluminescence toxicity test. Comparison between both assays confirmed that Vibrio fischeri is generally more sensitive than autotrophic bacteria, and, if not calibrated, the bioluminescence method tends to overestimate toxic effects on activated sludge biomass. The nitrification inhibition assay appears to predict plant process upsets more accurately. Both methods showed a significant toxicity decrease through treatment that could be partially attributed to the significant heavy metals removal obtained by primary and secondary treatment. A good correlation for the two assays was obtained, as indicated by a high correlation coefficient (r2 = 0.80).     

Toxicity evaluation of reactive dyestuffs, auxiliaries and selected effluents in textile finishing industry to luminescent bacteria Vibrio fischeri

The toxicity of 17 selected process effluents, 11 reactive dyestuffs and 8 auxiliaries from a textile dyeing and finishing mill in Ayazaga, Istanbul, Turkey was evaluated by bioluminescence test using bacteria Vibrio fischeri in LUMIStox 300. The EC20 and EC50 for auxiliaries, the EC20 for dyestuffs were determined. For selected process effluents GL-values, the dilution level at which a wastewater sample causes less than 20% inhibition, were examined. Our results demonstrate that the toxicity assessment with luminescent bacteria is effective and of practical use for chemicals applied in textile finishing industry with the limitation of the deep dark-colored dye bath samples and for the related effluents. Inhibition effects of numerous dyestuffs as well as auxiliaries to luminescent bacteria differed considerably with a range 5-600 mg l(-1) for EC20 and 9-6930 mg l(-1) for EC50, respectively. Among 17 effluents, I sample exhibited high toxicity (GL = 100), 7 showed moderate toxicity (GL = 12-32), and 9 had a GL-value <10 indicating a low or no toxicity.     

Development of a three-stage system for wastewater toxicity monitoring: a design and feasibility study.

A three-stage system was developed to automate a batchwise toxicity testing protocol designed for assessing wastewater toxicity to activated sludge. The three-stage system used the luminescent bacterium Shkl. The three stages were cell storage, cell activation, and continuous toxicity testing. Shkl cells were stored in a bioreactor at 4 degrees C when the system was not in use and activated in another bioreactor for use in toxicity tests conducted in a continuous manner. The system could quickly be switched between the "off" and "on" modes, and operation of the system was easy. The stability of the system, in terms of cell density and bioluminescence in the storage and activation bioreactors, and the response of the activated cells to a metal and an organic toxicant were studied. The feasibility of the system design was demonstrated by simulating zinc toxicity episodes in synthetic wastewater. The needs for further modifications and improvements of the system were discussed.     

Inhibition of heavy metals on fermentative hydrogen production by granular sludge

This study was conducted to investigate the toxicity of six electroplating metals on the H(2)-producing activity of a granular sludge sampled from an H(2)-producing upflow reactor treating sucrose-containing wastewater. The H(2) production activities of the sludge were measured in serum vials using wastewater containing not just sucrose and proper nutrient, but also individual heavy metals at concentrations ranging 0-5000 mg l(-1). The relative toxicity to H(2) production was found in the following order: Cu (most toxic)>Ni approximately Zn>Cr>Cd>Pb (least toxic). The C(I,50) values, at which the bioactivity of the sludge was reduced to 50% of the control, for individual heavy metals were Cu 30 mg l(-1), Ni and Zn 1600 mg l(-1), Cr 3000 mg l(-1), Cd 3500 mg l(-1), and Pb >5000 mg l(-1). Compared with the literature data, H(2)-producing sludge exhibited in general higher resistance to metal toxicity than methanogenic granular sludge.     

Toxicity of metals and organic chemicals evaluated with bioluminescence assays

The development of a bioluminescent sensor organism (Shk1) that was created for assessing wastewater toxicity was reported several years ago. In order to establish a test battery to better characterize wastewater toxicity, additional luminescent sensor organisms were later created. The present study focused on one promising candidate (PM6), a Pseudomonas spp. strain, because of its high level of luminescence compared to that of other newly created organisms. Using a batch toxicity testing protocol, the toxicity of 7 metals and 25 organic compounds was evaluated with the PM6 and Shk1 assays. Results indicated that the toxicity data of the PM6 and the Shk1 assays were correlated, and no assay appeared to be particularly more sensitive to a group of toxicants than the other assay. The results of the PM6 and Shk1 assays were further evaluated by comparing with the results of the Vibrio fischeri luminescence inhibition assay and activated sludge inhibition assays. Data suggested that PM6 and Shk1 more closely represented activated sludge organisms than V. fischeri. The suitability of using PM6 and Shk1 for assessing wastewater toxicity on activated sludge, both individually and in a test battery, was discussed.     

磺胺和四环素类抗生素对活性污泥性能的影响简

废水处理工艺中抗生素类污染物的存在可能会对生物处理过程产生长期而深远的影响，为探明此类污染物对废水生物处理主体活性污泥性能等方面的影响，采用间歇培养法研究了活性污泥法处理污水时，抗生素类污染物的存在对活性污泥性能如胞外聚合物（EPS）、污染物处理能力、脱氢酶活性和群落结构的影响。结果表明，抗生素的存在会导致活性污泥的胞外聚合物总量及其主要组分蛋白质和多糖增加，以产生保护屏障；且由于污泥絮体解体，细胞破裂导致EPS中DNA和色氨酸含量增加。同时，由于蛋白质大量增加引起的表面负电荷的增加，使污泥疏水性增强，絮凝性能恶化；污泥絮体解体导致污泥颗粒变小，SVI也随之下降；在活性污泥脱氢酶活性急剧下降的同时，出水TOC迅速升高。此外，抗生素类污染物在抑制活性污泥中大部分细菌的同时，对部分菌群也有刺激生长作用，最终导致活性污泥生物群落结构的改变。四环素类抗生素对活性污泥的EPS和絮凝沉降性能的影响大于磺胺类，而对污水处理能力和群落结构的影响则不如磺胺类。抗生素类污染物的长期存在会对活性污泥沉降性能、絮凝性能、脱氢酶活性以及活性污泥群落结构等产生一系列负面影响，进而影响污染物去除效果，导致出水水质恶化。     

Monitoring the toxicity of phenolic chemicals to activated sludge using a novel optical scanning respirometer.

This paper reports the development of optical scanning respirometer for determining the toxicity of chemicals to activated sludge. The respirometer is used to measure the dissolved oxygen concentration by monitoring the luminescence intensity of ruthenium dye immobilized in a polymer film in contact with the wastewater sample. The intensity is related to the extent of oxygen quenching of luminescence. The toxicity of chemicals can be evaluated by measuring the inhibition on respiration rate of microorganism using the scanning respirometer. The IC50 values (concentration of a chemical that exhibits 50% respiration inhibition) of various phenolic chemicals in activated sludge were determined. The performance of this method is compared with other toxicity methods. The experimental results indicate that the reproducibility and sensitivity of this respirometer are reasonably good.     

The effect of heavy metals on the activated sludge process and its microbial community analysis using 16S ribosomal DNA

The effect of heavy metal shock loading on biological treatment systems was studied by traditional methods and molecular biological techniques. Two kinds of SBR (sequence batch reactor) operation units, unacclimated and acclimated activated sludge systems, were studied. The addition of special nutrients and powdered activated carbon (PAC) to stimulate heavy metal uptake and recovery were studied. The kinetic constants could be used to describe the effect of the inhibition of substance utilisation. The results showed that heavy metal shock loading had a greater effect on the unacclimated activated sludge system than on the acclimated one. The special nutrients greatly enhanced the uptake of copper, and the PAC improved sludge settling and decreased the turbidity of the effluent. The variation of dominant species and the diversity of the bacterial community were analysed using 16S ribosomal DNA. Compared with the slight change of dominant species during acclimation by copper, there was a great change in the acclimated system shocked by a high concentration of copper. The results confirmed that the acclimation could improve the resistance of microorganisms to heavy metal toxicity.     

Determination of detoxification to Daphnia magna of four pharmaceuticals and seven surfactants by activated sludge

Pharmaceuticals are bioactive compounds generally resistant to biodegradation, which can make them problematic when they are released into nature. The use pattern for pharmaceuticals means that they are discharged into water via sewage treatment plants. Also surfactants are discharged through sewage treatment plants, primarily due to their use in detergents and shampoos and other cleaners. In this study the acute toxicity to Daphnia magna of four pharmaceuticals (ciprofloxacin, ibuprofen, paracetamol and zinc pyrithione) and seven surfactants (C8 alkyl glucoside, C6 alkyl glucoside, sodium caprylimidiopropionate, tallow-trimethyl-ammonium chloride, potassium decylphosphate, propylheptanol ethoxylate and alkylmonoethanolamide ethoxylate) was determined. Abiotic (without activated sludge bacteria) and biotic (with activated sludge bacteria) detoxification was also determined. The 24-h EC50s ranged from 2 μg L(-1) for the most toxic substance (zinc pyrithione) to 2 g L(-1) for the least toxic compound (C6 alkyl glucoside). Detoxification rates determined as the ratio between initial EC50 and EC50 after 1 week in water with activated sludge bacteria ranged from 0.4 (paracetamol) to 13 (zinc pyrithione). For most of these chemicals detoxification rate decreased after 1 week, but for one (alkylmonoethanolamide ethoxylate) it increased from about 2 to 30 times after 2 weeks. Many of these chemicals were "detoxified" also abiotically at about the same rate as biotically. Further studies are needed to determine the degradation products that were precipitated (aggregated) for some of the tested chemicals. Altogether, this study has shown that there are large differences in toxicity among chemicals entering sewage treatment plants, but also that the detoxification of them can differ. Therefore, the detoxification should receive more attention in the hazard and risk assessment of chemicals entering sewage treatment plants.