异噻唑啉酮耦合氧化钙对污泥压滤脱水及燃烧热值的影响

通过正交实验考察了异噻唑啉酮耦合氧化钙对压滤污泥含水率、燃烧热值、Zeta电位和泥饼含硫量的影响,结果表明,各因素对污泥含水率影响的大小顺序依次为:氧化钙投加量、压强、压滤时间、异噻唑啉酮投加量;各因素对污泥燃烧热值影响的大小顺序依次为:氧化钙投加量、压滤时间、异噻唑啉酮投加量和压强。异噻唑啉酮投加量为5.6 mg/g TSS,氧化钙投加量为120 mg/g TSS,压强为0.40 MPa,压滤时间为1 h条件下,污泥含水率为55.5%,105℃烘干泥饼的热值为10 702 J/g,Zeta电位值为-30.082 mV,泥饼含硫量为0.408%。此时污泥含水率较低,热值较高,含硫量较低,有利于污泥的焚烧处理。     

以再生水为补水的景观水体水华爆发特征调查和药剂应急控藻效果评价

采用现场调查和实验室验证的方法，对以再生水为景观补水的水华优势藻进行了分析。2年的现场调查表明，再生水在条件适合时极易发生水华，且水华的优势藻以小球藻为主。在实验室针对小球藻和铜绿微囊藻进行了竞争生长实验研究，在再生水的氮磷浓度范围内小球藻生长快于铜绿微囊藻，这也验证了再生水作为景观水补水时小球藻是优势藻现场调查结论。针对水华爆发初期和水华爆发验证时2种条件，比较研究了4种以化学成分为主的抑藻药剂对以小球藻为水华特征藻的控藻效果。结果表明，这4种药剂对水华的控制均具有一定的效果，并且水华初期实施药剂抑藻，药剂投加少，且效果好。对4种药剂进行急性毒性实验，只有S2一种药剂在安全浓度时对水华爆发初期有抑藻效果。     

二氧化氯杀灭小球藻

实验研究了二氧化氯投加量、小球藻的初始浓度、pH、有机物和氨氮含量对ClO2杀灭来自于水库水的小球藻的影响,考察了ClO2氧化与混凝工艺结合时去除小球藻的效果并对工艺条件进行优化。结果表明,ClO2在投加量1.1 mg/L下,接触10 min,小球藻的杀灭率为71.93%。小球藻的杀灭率随着ClO2投加量的增大和藻初始浓度的升高而提高,随水中有机物含量的增加而显著降低,氨氮含量对小球藻杀灭的效果影响很小。在酸性条件和碱性条件下,小球藻的杀灭率均随pH升高而急剧下降,而在中性至弱碱性区间内,藻的杀灭率随pH升高而缓慢下降。对于某以小球藻为优势藻的供水水库源水,ClO2氧化与混凝工艺结合,藻的去除率高达98.47%。除藻的最佳工艺条件为:二氧化氯投加量为0.5 mg/L,聚合氯化铝为5 mg/L,二氧化氯与混凝剂同时投加。     

二氧化氯杀灭小球藻

实验研究了二氧化氯投加量、小球藻的初始浓度、pH、有机物和氨氮含量对ClO2杀灭来自于水库水的小球藻的影响,考察了ClO2氧化与混凝工艺结合时去除小球藻的效果并对工艺条件进行优化。结果表明,ClO2在投加量1.1 mg/L下,接触10 min,小球藻的杀灭率为71.93%。小球藻的杀灭率随着ClO2投加量的增大和藻初始浓度的升高而提高,随水中有机物含量的增加而显著降低,氨氮含量对小球藻杀灭的效果影响很小。在酸性条件和碱性条件下,小球藻的杀灭率均随pH升高而急剧下降,而在中性至弱碱性区间内,藻的杀灭率随pH升高而缓慢下降。对于某以小球藻为优势藻的供水水库源水,ClO2氧化与混凝工艺结合,藻的去除率高达98.47%。除藻的最佳工艺条件为：二氧化氯投加量为0.5 mg/L,聚合氯化铝为5 mg/L,二氧化氯与混凝剂同时投加。     

臭氧对河道典型藻类的影响研究

为探究臭氧工艺应用于河道等污染水体控制藻类的可行性,分别针对水体浮游藻类和附着藻类开展臭氧投加影响实验。结果表明:(1)投加臭氧30min后,浮游藻类铜绿微囊藻(Microcystis aeruginosa)和尖针杆藻(Corynebacterium albicans)藻细胞密度随臭氧浓度的增加而下降,臭氧胁迫影响的质量浓度阈值为4mg/L,此浓度下,细胞出现大量死亡,且此后15d内很难得到恢复。(2)附着藻类受臭氧胁迫的质量浓度阈值为3mg/L。3mg/L臭氧水中藻生物膜的总生物量、叶绿素a、胞外多糖和脱氢酶活性均较原水低,但随着时间的延长,各项指标基本都表现出了与原水差距缩小的趋势,说明附着藻类有较强的恢复能力。     

增蓝剂停留时间及对水质和浮游植物影响分析

水体遮光剂能干扰水下光照,抑制藻类生长。为了探讨水体遮光剂-增蓝剂在自然水体的作用情况,对围隔内增蓝剂的停留时间及水质、浮游藻类和沉水植物的变化特征进行分析。结果表明,当围隔水体中增蓝剂浓度为1 mg/L时,5周内其降解超过50%,9周后降解超过95%。与对照组相比,增蓝剂对围隔内总氮、总磷浓度无明显影响,易氧化成分的存在导致CODMn浓度升高至8.60 mg/L,但CODMn浓度随增蓝剂的降解逐步降至7.81 mg/L。在增蓝剂作用下水下光照度衰减明显,水深0.2 m处仅占水表面光强的21.16%,光衰减系数(k)为0.7 m-1。增蓝剂对藻类生长抑制作用明显,抑制率高达56.24%,但对金鱼藻生长无显著影响。     

电催化氧化处理除草剂异噁草酮废水的效能

为有效处理含异噁草酮除草剂废水，以Sb掺杂Ti／SnO2电极为阳极，不锈钢板为阴极，采用电催化氧化技术对异噁草酮废水进行降解，研究了不同影响因素对异噁草酮去除率的影响，并分析了异噁草酮的降解效果。结果表明，当异噁草酮初始浓度为100mg／L、电流密度为20mA／cm2、电解质投加量为0．10mol／L，反应120min后，异噁草酮去除率达到94％，此时TOC去除率为57．9％，能耗为25kWh／m2，且废水的可生化性能显著提高。     

电催化氧化处理除草剂异草酮废水的效能简

为有效处理含异草酮除草剂废水，以Sb掺杂Ti/SnO₂电极为阳极，不锈钢板为阴极，采用电催化氧化技术对异草酮废水进行降解，研究了不同影响因素对异草酮去除率的影响，并分析了异草酮的降解效果。结果表明，当异草酮初始浓度为100 mg/L、电流密度为20 mA/cm²、电解质投加量为0.10 mol/L，反应120 min后，异草酮去除率达到94%，此时TOC去除率为57.9%，能耗为25 kWh/m³，且废水的可生化性能显著提高。     

H2O2预氧化颤藻及其复合高岭土除藻性能研究

为了降低给水中藻类浓度,以过氧化氢为预氧化剂,预氧化藻后加入的高岭土、PAC分别为助凝剂和絮凝剂,对混凝去除颤藻进行了研究.结果表明,H2O2具有显著预氧化抑制藻活性的功能,投加量为2.5 mg/L时可抑制其生长活性20 d以上.在实验水质条件下,通过正交实验得出最佳复配条件是:H2O2投加量为2.5 mg/L,预氧化...     

不同遮光方式的抑藻效果比较研究

藻类的生长繁殖与其自身通过光照进行光合作用有着密不可分的关系。研究了遮光面积、遮光周期、遮光率与水体叶绿素a含量和藻类密度之间的关系，探讨不同遮光方式对藻类生长的抑制作用；以及不同遮光方式下水体中氮磷浓度的变化情况。实验结果显示：遮光50%以上的实验桶内的叶绿素a含量和藻类密度相对于不遮光减少50%以上；从上午9：00至下午3：00遮光，12 d可以使绿素a浓度和藻类数量相对于不遮光减少70%以上；遮光率达到67%以上时，抑藻效果才较为明显，第12 d时，叶绿素a含量和藻类密度相对于不遮光减少50%以上。遮光是抑制藻类暴发的有效措施之一，不同水体可以根据具体情况选择不同的遮光方式。     

环境因子对汾河水上公园再生水中藻类生长的影响

实验根据太原市气候状况选取了不同温度和光照梯度条件，根据实验水质特征选取了不同的氮磷浓度值，研究了温度、光照、氮磷营养盐等环境因子对再生水回用于景观用水产生的主要藻类小球藻形成水华的影响效果。结果表明，温度升高、光照强度增加和光照时间延长可促进小球藻的生长繁殖；氮磷比对小球藻的生长影响较大，其中，小球藻在氮磷比为10：1-30：1时生长繁盛，氮磷比为44：1时生长受到抑制，即磷作为限制性营养盐，可抑制水华的发生；pH和溶解氧的变化趋势与藻细胞数的变化趋势一致，可作为水体发生水华的快速监测指标。     

硝态氮为惟一氮源时异养微生物增长特性

采用SBR研究了缺氧条件下硝态氮为惟一氮源时异养微生物的增长特性。结果表明,异养微生物能利用硝态氮作为氮源进行增殖。当进水COD浓度为1 400 mg/L,硝态氮浓度为280 mg/L时,COD和硝态氮的去除率分别达到97%和99%;污泥中微生物的含氮量为8.8%,低于常规利用氨氮作为氮源的微生物;在实验条件下活性污泥的产率系数为0.30 g VSS/g COD。反硝化菌可利用硝态氮作为氮源进行细胞合成对含硝氮的废水处理具有重要意义。一方面由于无需投加氨氮降低了废水处理成本,另一方面由于污泥产率低,降低了污泥处理成本。     

Effects of thiobencarb herbicide to an alga (Nannochloris oculata) and the cladoceran (Daphnia magna)

Chronic toxicity studies were conducted with an algae (Nannochloris oculata) and the cladoceran (Daphnia magna) to determine their relative sensitivities to the thiocarbamate herbicide thiobencarb (S-4-chlorobenzyl diethylthiocarbamate). Most of the algal populations were initially affected by exposure to the herbicide. Thiobencarb concentrations higher than 0.5 mg/L significantly reduced algal densities after 24-h exposure. The 24-h static EC50 in D. magna was 3.01 mg/L. The sublethal effects of 0.3, 0.37, 0.5, 0.75, and 1.5 mg/L of thiobencarb concentrations on the survival, reproduction, and growth of D. magna were monitored for 21 days. The parameters used to determined the effect of the herbicide on D. magna were mean total young per female; mean brood size; days to first brood; intrinsic rate of natural increase (r); growth; and survival. Reproduction was significantly reduced at thiobencarb concentrations of 0.30 mg/L and higher while survival was affected after exposure to 0.75 and 1.5 mg/L of the pesticide. The r value decreased with increasing concentrations of thiobencarb. Growth, as measured by body length, was depressed significantly after exposure to all herbicide concentrations tested.     

Toxicity mechanism of cerium oxide nanoparticles on cyanobacteria Microcystis aeruginosa and their ecological risks

The extensive application of cerium oxide nanoparticles (CeO₂ NPs), a type of rare earth nanomaterial, led to pollution into aquatic environments. Cyanobacteria, a significant component of freshwater ecosystems, can interact with CeO₂ NPs. However, little attention has been paid as to whether CeO₂ NPs will have adverse effects on cyanobacteria. In the present study, Microcystis aeruginosa (FACHB-942) was exposed to different concentrations (0, 1, 10, and 50 mg/L) of CeO₂ NPs. Results showed 50 mg/L CeO₂ NPs inhibited algal growth (11.48%?±?5.76%), suppressed photosynthesis and induced the generation of reactive oxygen species (ROS) after 72 h exposure. The toxicity mechanism is the adsorption of CeO₂ NPs on cell surface, the ROS formation and the intracellular Ce. Additionally, the intracellular microcystins (MCs) content was significantly induced (11.84%?±?1.47%) by 50 mg/L CeO₂ NPs, while no significance was found in 1 and 10 mg/L CeO₂ NP treatments. Results indicated high concentrations of CeO₂ NPs could be toxic to algae through the adverse effects on algal growth and photosynthesis. Moreover, the promoted MCs production could also pose a threat to freshwater ecosystems due to the possible release into the environment.

     

Phytotoxicity of coloured substances: is Lemna duckweed an alternative to the algal growth inhibition test?

Coloured substances cause problems when interpreting algal tests, because effects due to light absorption can interact with potential toxicity. The Lemna Duckweed growth inhibition test can complement the algal test, on condition that the test is performed on a black, not reflecting surface. On white surfaces, test solution colour can strongly impact Lemna growth. For example, average control sample growth rate of is much higher on white surfaces (0.362 d(-1)) than on black surfaces (0.284 d(-1)). We found that 10 mg l(-1) of the dyestuff "Brilliant Blue R spezial" inhibited average Lemna growth rate about 22% on white surfaces but did not inhibit growth on black surfaces. The reason for this difference stems from the difference in amount of light reflected from below the test beakers. With Brilliant Blue on white surfaces, the test solution colour reduces utilizable light and causes a deterioration of light conditions, whereas on a black surfaces, reflected light is absent a priori, and thus no inhibiting effect was measured. Of particular importance is the choice of test parameter. With Brilliant Blue, a LOEC for average growth rate, based on frond numbers, of 320 mg l(-1) was determined. However, when average growth rate was calculated using dry weights of the plants, the LOEC decreased clearly to 1.0 mg l(-1). In this study, the Lemna test was much more sensitive than the algal test. We recommend Lemna tests be used in addition to algal tests, because doing so may significantly improve the assessment of phytotoxicity of chemicals and sewage.     

Toxicity of Heavy Metals on Scenedesmus quadricauda (Turp.) de Brébisson in Batch Cultures (7 pp)

Background Aquatic environments are often exposed to various pollutants like heavy metals that are released from industrial, agricultural and domestic wastes. Emissions of heavy metals can then enter all ecosystems and bring about severe problems in plants, especially algae depending on the concentrations of a given element. The objective of the investigation presented is to detect toxic effects due to some heavy metals in the biomass of green alga Scenedesmus quadricauda. Methods All experiments were conducted with axenic cultures of the green alga Scenedesmus quadricauda (Turp.) de Brebisson (Chlorococcales, Chlorophyta). The cultures were grown in Chu-no.10 medium, and optimum physical and chemical growth conditions were provided to get higher growth rates and lower doubling times of cells. Growth of the micro algal cultures was measured on a daily schedule by counting cultures and determination of chlorophyll-a. The sterile-filtered heavy metal concentration solutions (Cd, Pb and Cu) were prepared and added as stock solutions of their salts (CdCl2*2.5 H2O, Pb(NO3)2*H2O and CuSO4*5 H2O). Results and Discussion The growth decreased gradually with the alga exposed to Cd at 0.05, 0.1, and 0.5 mg/L in comparison with the control whereas 1 mg/L Cd2+ had a clearly destructive effect. The growth was decreased with Pb at 15, 20 and 25 mg/L gradually, while at 30 mg/L the effect was more pronounced. When Cu was used, the growth was increased gradually at 0.5, 1 and 1.5 mg/L and vice versa at 2 mg/L. Conclusion There were differences in toxic effects of the metals with different metal as well as their concentrations and the time of exposure.     

原位投菌技术修复微污染水源水的中试研究

针对水源水库的氮源污染和有机物污染问题,研究了原位投菌技术对微污染水源水的修复效果。实验在中试反应器中进行,所投加菌剂为贫营养好氧反硝化细菌。实验结果表明,在菌剂投加量为0.1 mg/L,溶解氧质量浓度为5～8 mg/L,水温为16～25℃的条件下,系统对水中主要污染物NO3--N、TN和CODMn均有较好的去除效果,质量浓度分别从1.68、2.25、5.50 mg/L降至最低值0.75、0.95、3.03 mg/L,最大去除率分别可达到57.5%、57.7%和44.9%。系统对水中氮源污染和有机物的去除效果均能够满足《地表水环境质量标准》中的Ⅲ类标准,实验结果表明,将原位投菌技术应用于微污染水源水体的水质改善是可行的。同时还探讨了贫营养好氧反硝化细菌的作用机理。     

Vegetable and synthetic tannins induce hormesis/toxicity in sea urchin early development and in algal growth

Mimosa tannin and phenol-based synthetic tannin (syntan) were tested for toxicity to sea urchin (Paracentrotus lividus and Sphaerechinus granularis) early development and to marine algal growth (Dunaliella tertiolecta). Sea urchin embryogenesis was affected by vegetable tannin and syntan water extracts (VTWE and STWE) at levels >or=1mg/L. Developmental defects were significantly decreased at VTWE and STWE levels of 0.1 and 0.3mg/L when control cultures displayed suboptimal quality, i.e. <70% "viable" (normal or retarded) larvae. Fertilization success of sea urchin sperm was increased up to 0.3 mg/L STWE or VTWE, then was inhibited by increasing tannin levels (1-30 mg/L). Offspring abnormalities, following sperm exposure to VTWE or STWE, showed the same shift from hormesis to toxicity. Cell growth bioassays in D. tertiolecta exposed to VTWE or STWE (0.1-30 mg/L) showed non-linear concentration-related toxicity. Novel criteria are suggested in defining control quality that should reveal hormetic effects.     

Polystyrene nanoplastics affect growth and microcystin production of Microcystis aeruginosa

Nanoplastics are widely distributed in freshwater environments, but few studies have addressed their effects on freshwater algae, especially on harmful algae. In this study, the effects of polystyrene (PS) nanoplastics on Microcystis aeruginosa (M. aeruginosa) growth, as well as microcystin (MC) production and release, were investigated over the whole growth period. The results show that PS nanoplastics caused a dose-dependent inhibitory effect on M. aeruginosa growth and a dose-dependent increase in the aggregation rate peaking at 60.16% and 46.34%, respectively, when the PS nanoplastic concentration was 100 mg/L. This caused significant growth of M. aeruginosa with a specific growth rate up to 0.41 d^?1 (50 mg/L PS nanoplastics). After a brief period of rapid growth, the tested algal cells steadily grew. In addition, the increase in PS nanoplastics concentration promoted the production and release of MC. When the PS nanoplastic concentration was 100 mg/L, the content of the intracellular (intra-) and extracellular (extra-) MC increased to 199.1 and 166.5 μg/L, respectively, on day 26, which was 31.4% and 31.1% higher, respectively, than the control. Our results provide insights into the action mechanism of nanoplastics on harmful algae and the potential risks to freshwater environments.

     

Inhibitory effect of ragweed (Ambrosia artemisiifolia L)-inflorescence extract on the germination of Amaranthus hypochondriacus L and growth of two soil algae

In this study the ecological importance of common ragweed (Ambrosia artemisiifolia L.; Asteraceae) was investigated in in vitro bioassays as it is one of the most widespread annual weeds occurring on arable land in Hungary. Eight fractions were derived from ragweed inflorescence water extract by low vacuum column chromatography and their biological activity was investigated by Amaranthus hypochondriacus L. cv. Edit (Amaranthaceae) germination bioassay. As a result of the germination bioassay the chromatographic method was modified to harvest the most effective fractions in only one fraction, which was used in three concentration (10, 50, 100 mg x kg(-1)) for algal growth inhibition bioassay.Results showed significant growth inhibition in case of both applied algal species.