异步周期换向电凝聚法处理活性艳蓝X-BR模拟染料废水及其机理研究

针对传统电凝聚法处理废水过程中易出现的电极表面钝化和极化而影响处理效果的现象,采用铝和铁板作为两极同步换向方法,通过周期性改变电流方向使电极钝化和极化现象得以减缓或消失,并实现两极均可溶,利用铝、铁系无机絮凝剂共存时可提高处理效果的特点,对活性艳蓝X-BR模拟染料废水进行处理;通过正交试验,获得了该方法的最佳处理条件.在此基础上,为避免金属铝成分在废水中出现剩余影响水质,采用异步周期换向方式加以改进,考察了铝、铁电极不同通电时间对处理效果的影响,并利用紫外-可见光分光光度法、高效液相色谱法、ICP法、高分辨质谱技术、激光粒度分析仪等手段对废水处理过程主导因素和污染物去除机理以及该方法对强化处理效果的作用机理进行了分析.研究表明,最佳条件下采用异步换向周期电凝聚法处理活性艳蓝X-BR模拟染料废水30 min可使模拟废水脱色率接近100%,COD去除率可达76%以上;处理过程中起主导作用的是电凝聚过程而非电氧化还原过程;除大部分染料分子被电凝聚气浮或沉降导致脱色外,其余的活性艳蓝X-BR染料分子在电解作用下首先断裂生成了1,4-二氨基蒽醌-2-磺酸根,之后1,4-二氨基蒽醌-2-磺酸根又被直接絮凝上浮或沉降,或者在氢离子作用下发生了加氢反应使双键消失而脱色,模拟废水脱色是上述作用的综合结果.采用改进后的异步周期换向电凝聚法可以使铝铁离子凝聚过程形成的絮体具有更为合理的粒度和结构特性,从而更易于被去除,因此处理效果略优于同步换向和定向电流电凝聚过程,且可以实现处理后废水中铝离子含量降低到无法检出,避免其在处理后的废水中出现剩余影响水质.     

Innovative combined technique for high concentration of azo dye AR18 wastewater treatment using modified SBR and enhanced Fenton process as post treatment

The purpose of this research was to evaluate the performance of combined biological/advanced oxidation process (AOP) system for treatment of wastewater containing high concentration (500 mg/L) of azo dye Acid Red 18 (AR18). Two alternating anaerobic–aerobic sequencing batch reactors (SBR1 and SBR2 without and with external feeding at the beginning of aeration cycle, respectively) were operated. The effluent of the SBRs was then post treated through enhanced Fenton process (using zero-valent iron combined with ultrasonic irradiation). More than 90% and 97% of COD was removed in the combined SBR/AOP system without external carbon source (CTS1) and with external feeding (CTS2), respectively. The analysis of dye and its metabolites using UV–vis and HPLC analysis also proved that 99% of the original dye was decolorized and more than 89% of its metabolites were degraded through CST2 which is significantly higher than the reported values in the literature. Besides, more than 87% of phosphorus removal efficiency was obtained in CST2 compared to only 54.5% removal efficiency in CST1. Regarding the findings of this study, the proposed combined treatment system (CTS2) can be suggested as an effective technique for treatment of high azo dye AR18 concentration wastewater.     

Evaluation of Bacillus sp. MZS10 for decolorizing Azure B dye and its decolorization mechanism

To evaluate decolorization and detoxification of Azure B dye by a newly isolated Bacillus sp. MZS10 strain, the cultivation medium and decolorization mechanism of the isolate were investigated. The decolorization was discovered to be dependent on cell density of the isolate and reached 93.55%(0.04 g/L) after 14 hr of cultivation in a 5 L stirred-tank fermenter at 2.0 g/L yeast extract and 6.0 g/L soluble starch and a small amount of mineral salts. The decolorization metabolites were identified with ultra performance liquid chromatography-tandem mass spectroscopy(UPLC-MS). A mechanism for decolorization of Azure B was proposed as follows: the C=N in Azure B was initially reduced to –NH by nicotinamide adenine dinucleotide phosphate(NADPH)-dependent quinone dehydrogenase, and then the –NH further combined with –OH derived from glucose to form a stable and colorless compound through a dehydration reaction. The phytotoxicity was evaluated for both Azure B and its related derivatives produced by Bacillus sp. MZS10 decolorization, indicating that the decolorization metabolites were less toxic than original dye. The decolorization efficiency and mechanism shown by Bacillus sp. MZS10 provided insight on its potential application for the bioremediation of the dye Azure B.     

高浓度聚合氯化铁混凝剂的净水效果

采用共聚方法制备聚合氯化铁混凝剂．试验了它对模拟水的除浊和脱色效果,对高、中、低浊度的地表水以及炼油废水的处理效果．实验结果表明：与FeCl3相比,聚合氯化铁(PFC)具有更好的除浊、脱色效果,COD去除率、除油率的效果大大提高;W／Fe摩尔比对PFC混凝效果的影响不尽相同,在实际水处理中,应根据处理对象的不同,选择合适的参数以达到最佳的混凝效果．     

电化学方法生成羟基自由基及其在酸性铬蓝降解脱色中的应用1)

在电解槽中,以Ｎａ２ＳＯ４为支持电解质,多孔石墨电极为阴极,金属铁为阳极,在１０ｍＡ·ｃｍ－２的阴极电流密度下,电解生成的过氧化氢与阳极溶解的Ｆｅ２＋进行反应,生成羟基自由基(Ｆｅｎｔｏｎ试剂),进而对有机染料进行氧化反应,使其不饱和双键断裂,从而达到有机染料降解、脱色的目的,在生成Ｆｅｎｔｏｎｎ试剂的反应中,Ｆｅ２＋被氧化为 Ｆｅ３＋,生成的 Ｆｅ３＋在阴极得电子后重新被还原为Ｆｅ２＋,因此,在电解槽中 Ｆｅ２＋起着催化剂的作用．ＣＯＤ的去除率大于８０%,脱色率达１００%．脱色速率的测定表明其为一级反应,反应速度常数ｋ等于ｌ．９８ × １０－４ｓ－１．     

基因工程菌在SMBR中对直接耐晒蓝的脱色

文章优化了基因工程菌Escherichia coli JM109(pGEX-AZR)对三偶氮染料直接耐晒蓝(B2RL)的脱色条件,并考察其在SMBR中对直接耐晒蓝的脱色效果。研究表明,最佳脱色条件为:进水浓度400mg/L,初始生物量5g/L,pH7.0～8.0,葡萄糖浓度0.5g/L。在此条件下,基因工程菌在SMBR中对直接耐晒蓝的脱色率稳定在90%以上,对COD的去除率范围50%～62%。系统运行过程中,反应器内生物量稳定在3.90g/L左右;酶活力和EPS均呈现先增大,再降低,最后较为平缓的趋势;系统运行周期约为25d。     

耐盐菌对偶氮染料酸性红B的脱色研究

从食品加工厂含盐污水处理车间的活性污泥中分离出对偶氮染料具有脱色活性的耐盐菌体,研究了不同pH值、脱色温度、接菌量以及装液量等条件对耐盐菌体降解酸性红B的影响,并设计正交实验,获得其降解模拟偶氮染料废水的最佳反应条件.研究结果表明,耐盐菌体TAS在35℃、pH为8、装液量为50mL及接菌量为8%(体积分数)的条件下,反应10h后对浓度为50mg·L-1的酸性红B模拟废水的脱色率达91%.     

印染废水脱色技术与理论述评

文章介绍了印染废水典型脱色技术的现状和进展,并着重分析了各种脱色技术的脱色机制,突出了典型脱色技术中的理论因素,介绍并阐明了一些脱色理论新观点,如吸附剂改性增效原理、分子结构与絮凝效果的联系、小剂量氧化剂偶合絮凝、脱色菌的质粒对脱色率的影响等,并从工艺角度分析了各种脱色方法的应用.     

电化学法生成Fenton试剂及其在工业染料废水降解脱色中的应用

以多孔石墨电极为阴极 ,电解时在阴极通以氧气或空气 ,电解生成的过氧化氢与阳极溶解的Fe2 +进行随后化学反应 ,现场生成羟基自由基 (Fenton试剂 ) ,进而对有机染整工业废水进行降解脱色反应。以可见光吸收谱图表征了工业染料废水经电解槽处理后吸光度的变化 ,以重铬酸钾法测试染料处理后的COD。实验结果表明 ,COD的去除率大于 80 % ,染料的脱色率达 1 0 0 % ,若将电解电流密度控制在 1 0mA/cm2 以下 ,槽电压可控制在 5V以内。实验结果表明 ,向阴极多孔石墨电极中通入空气与通入氧气的效果一致。     

溶液pH及电流浓度对电化学法生成羟基自由基降解机制的影响

用电化学稳态极化曲线分析方法讨论了溶液pH值及电流浓度对染料降解脱色的影响.实验结果表明,pH值将影响着阴极反应的方向、电极电位与染料降解脱色的效果.在酸性溶液中有利于过氧化氢的生成,阴极电位较低,但不利于随后的絮凝步骤;在中性溶液中染料降解脱色的综合效果较好,COD_Cr去除率可达80%以上.文中还讨论了电流浓度对降解脱色效果的影响,当电解槽内电流浓度达0.5 A/L时可取得满意的效果,电流浓度太大时,体系将伴随着析出氢气等的副反应,降解反应的电流效率下降.