A study on genotoxicity of textile dyeing industry effluents from Rajshahi,Bangladesh, by the Allium cepa test

Textile dye effluents are believed to be toxic as they might exert various harmful effects on living organisms including genotoxicity. These effluents are the main source of direct and continuous input of pollutants into the aquatic ecosystems. In this study, dye effluents from a local silk dyeing industry were analysed for their genotoxic potential by the Allium cepa genotoxicity test. The A. cepa test is characterised as a genotoxicity test where the roots of A. cepa are grown in different concentrations of the test material. The macroscopic results clearly showed that the toxicity of the dye effluents prompted A. cepa root growth inhibition, and this effect increased with higher concentrations of the effluents. At the cellular level, no dividing cells were found at higher concentrations such as 60%, 80% and 100% of the effluents. However, at a lower concentration of 20%, dividing cells were identified, although the mitotic index was much lower than that of the control. Microscopic analysis showed that the dye effluents induced chromosomal aberrations at significant levels. Taken together, these results revealed that the textile dyeing industry effluents are toxic to eukaryotic cells and these dyes have genotoxic properties that can potentially lead to cancer development and adverse health conditions.     

粉煤灰负载铁离子催化氧化活性黄染料废水

以粉煤灰为载体,制备铁/粉煤灰负载型催化剂,并利用该催化剂催化H2O2氧化降解活性黄染料废水,探讨了H2O2投加量、催化剂投加量、染料初始浓度和初始pH值等因素对染料废水COD去除率和脱色率的影响。结果表明,当染料废水COD初始浓度为200 mg/L,初始pH值为1.7,投加0.5 g/100 mL催化剂及加入1.0 mL浓度为1.13 mol/L的H2O2溶液时,处理效果最好,此时染料废水的COD去除率和脱色率分别达到63%和99%,并且废水的可生化性得到很大的提高。利用该负载催化剂能够有效地减少活性黄染料废水中Fe3+的残留量。     

New methodological improvements in the Microtox® solid phase assay

The classic Microtox® solid phase assay (MSPA) based on the inhibition of light production of the marine bacteria recently renamed Aliivibrio fischeri suffers from various bias and interferences, mainly due to physico-chemical characteristics of the tested solid phase. To precisely assess ecotoxicity of sediments, we have developed an alternative method, named Microtox® leachate phase assay (MLPA), in order to measure the action of dissolved pollutants in the aqueous phase. Two hypotheses were formulated to explain the observed difference between MSPA and MLPA results: a real ecotoxicity of the solid phase or the fixation of bacteria to fine particles and/or organic matter. To estimate the latter, flow cytometry analyses were performed with two fluorochromes (known for their ability to stain bacterial DNA), allowing correction of MSPA measurements and generation of new (corrected) IC50. Comparison of results of MLPA with the new IC50 MSPA allows differentiating real ecotoxic and fixation effect in classic MSPA especially for samples with high amount of fines and/or organic matter.     

零价铁复合有机膨润土处理染料废水的研究

针对目前印染废水处理现状及膨润土在水处理中回收困难等问题,提出将零价铁复合到有机膨润土中制成零价铁复合有机膨润土(ZVI-OB),以达到高效吸附并降解污染物的目的。以染料废水(Orange II) 作为研究对象,考察了废水中染料的初始浓度、pH以及吸附时间对ZVI-OB去除染料效率的影响,并研究了吸附后降解过程中时间和pH对污染物降解的影响以及降解前后膨润土层结构的变化。研究结果表明,ZVI-OB相对于CTMAB改性的有机膨润土而言,其吸附量有所降低,但ZVI-OB在吸附污染物之后能有效降解有机物。ZVI-OB在饱和吸附Orange II后经催化氧化,总有机碳含量降低为原来的19%,可以重复利用。     

ClO2氧化法预处理联苯胺类染料中间体废水

采用ClO₂氧化法预处理联苯胺类染料中间体生产废水,探讨了影响COD和联苯胺去除率的主要因素,并采用GC/MS技术对ClO₂氧化前后废水中的有机组分进行了分析。实验确定了较佳的工艺参数：ClO₂加入量为45~55 mg/L,ClO₂与联苯胺的化学计量比控制在（3.0~3.5）∶1,反应时间为 30~35 min。在此条件下,ClO₂氧化后出水中联苯胺去除率达到80%以上,联苯胺类污染物含量得到有效降低,废水BOD₅/COD由原水的0.18提高到0.40。该方法能提高废水的可生化性,是一种较好的生化预处理技术。     

Fenton试剂氧化法处理染料结晶废母液

采用Fenton试剂氧化法处理分散橙、分散紫和分散蓝3种染料结晶废母液。研究了H₂O₂加入量、n（H₂O₂）#x02236;n（Fe²⁺）和废母液pH对COD去除率或TOC去除率的影响。对TOC去除反应分段进行了动力学方程拟合,并探讨了反应机理。实验得到的分散橙、分散紫和分散蓝的废母液处理工艺条件：H₂O₂加入量分别为264.4,352.9,441.2mmol/L;n（H₂O₂）#x02236;n（Fe²⁺）分别为20,10,20;废母液pH=3。3种废母液在0~20min和20~120min两个阶段的反应与二级动力学拟合方程的相关性最好。3种废母液经Fenton试剂氧化处理后,部分有机物降解为小分子有机酸,部分有机物完全矿化。     

Deposition of aerially sprayed mexacarbate on balsam fir canopy and the forest floor: Relevance to ULV applications

Abstract

Spray deposit patterns were measured on aluminum coils and live balsam fir needles at different canopy heights, following aerial application of mexacarbate (4‐dimethylamino‐3,5‐xylyl N‐methylcarbamate) over a conifer forest in New Brunswick. Droplet size spectra of the spray cloud were determined on cylindrical Kromekote® cards placed at the corresponding crown heights. Ground deposits were collected on cylindrical Kromekote cards, aluminum coils and natural balsam fir foliage placed In forest clearings and under different types of vegetation.

Canopy deposits decreased progressively from the top to the bottom level of the tree crown. This trend was observed on aluminum coils, live fir foliage, and Kromekote cards. Droplet size spectra were similar at all sampling heights of the tree crown, and were comparable to those obtained on the ground cards placed in the forest clearings. Deposits of mexacarbate obtained on ground samplers on the open forest floor were markedly lower than those found at the top canopy but were similar to those at the mid or bottom canopy level. Droplet size spectra and mexacarbate deposits obtained on samplers placed under different types of forest vegetation indicated a selective filtration of the large droplets present in the spray cloud by plant canopies.     

A method for the determination of rhodamine b and brilliant sulfaflavine on cotton string collectors and in a spray tank solution mixture

Abstract

A fluorescent method for the determination of rhodamine B (RhB) and brilliant sulfaflavine (BSF) dual tracers on cotton string collectors and in spray tank solutions was developed for the evaluation of the effects of adjuvants on the atmospheric drift of agricultural sprays. Both tracers on collectors were extracted with deionized water simultaneously and measured directly with a Fluorescent Specrometer by switching the maximum excitation and emission wavelengths. The linear ranges of the RhB and BSF standard curves were 0–50 and 0–10 ppb respectively. Recoveries of tracers on cotton strings ranged from 92.9% ± 1.1% to 95.1% ± 1.0% for RhB and 91.9% ± 2.8% to 103% ± 0.6% for BSF when spiked levels ranged from 0.25 to 2.5 μg per collector. The detection limit of the instrument was approximately 0.1 ppb for both tracers. The detection limits of the analytical method were approximately 0.1 ppb for RhB and 0.3 ppb for BSF when the background levels of cotton strings were subtracted. The presence of one tracer in the solution did not significantly interfere with the detection of the other tracer in the same solution. The presence of adjuvants added to the spray tank solutions did not interfere with the detection of both tracers when the adjuvants were applied at the manufacturer's maximum recommendation rates.     

UASB反应器降解活性染料废水的特性

中温（35±1）℃条件下,采用上流式厌氧污泥床（upflowanaerobicsludgebed,简称UASB）反应器处理了含蒽醌类-活性艳蓝（c．I．ReactiveBlue5,简称K—GR）或偶氮类-活性艳红（C．I．ReactiveRed20,简称KD-8B;C．I．ReactiveRed2,简称X-3B）模拟染料废水,重点研究了回流比对染料脱色率和COD去除率的影响,在最佳回流比的条件下,探讨HRT（hydraulicretentiontime）对脱色的影响和不同结构染料的脱色效果,并初步分析了脱色机理。结果表明,适宜的回流比有利于提高系统的脱色率;控制回流比和HRT分别为2和24h,当模拟废水中染料的浓度为100mg／L时,COD去除率和脱色率分别为90％～96％和85％～92％;蒽醌和偶氮类染料的脱色是通过偶氮键和葸醌共轭结构的断裂来实现的。     

Adsorption of basic dye from aqueous solution onto fly ash

The fly ash treated by H₂SO₄ was used as a low-cost adsorbent for the removal of a typical dye, methylene blue, from aqueous solution. An increase in the specific surface area and dye-adsorption capacity was observed after the acid treatment. The adsorption isotherm and kinetics of the treated fly ash were studied. The experimental results were fitted using Langmuir and Freundlich isotherms. It shows that the Freundlich isotherm is better in describing the adsorption process. Two kinetic models, pseudo-first order and pseudo-second order, were employed to analyze the kinetic data. It was found that the pseudo-second-order model is the better choice to describe the adsorption behavior. The thermodynamic study reveals that the enthalpy (ΔH⁰) value is positive (5.63 kJ/mol), suggesting an endothermic nature of the adsorption.