Anaerobic/aerobic treatment of coloured textile effluents using sequencing batch reactors

Conventional biological wastewater treatment plants do not easily degrade the dyes and polyvinyl alcohols (PVOH) in textile effluents. Results are reported on the possible advantages of anaerobic/aerobic cometabolism in sequenced redox reactors. A six phase anaerobic/aerobic sequencing laboratory scale batch reactor was developed to treat a synthetic textile effluent. The wastewater included PVOH from desizing and an azo dye (Remazol Black). The reactor removed 66% of the applied total organic carbon (load F: M 0.15) compared to 76% from a control reactor without dye. Colour removal was 94% but dye metabolites caused reactor instability. Aromatic amines from the anaerobic breakdown of the azo dyes were not completely mineralised by the aerobic phase. Breakdown of PVOH by the reactor (20-30%) was not as good as previous reports with entirely aerobic cultures. The anaerobic cultures were able to tolerate the oxygen and methane continued to be produced but there was a deterioration in settlement.     

水解酸化/MBR处理偶氮染料废水的研究

采用水解酸化/MBR工艺处理活性艳红X-3B偶氮染料废水.结果表明,水解酸化/MBR工艺对活性艳红X-3B偶氮染料废水的处理效果较好,平均脱色率为81.58%,对COD和氨氮的平均去除率分别为83.53%、80.39%;对各工艺单元进、出水的紫外-可见吸收光谱分析表明,兼氧微生物通过水解酸化作用可将活性艳红X-3B染料分子中的偶氮双键、苯环、蔡环和二氯均三嗪活性基等降解,形成易被生物降解的小分子有机物,提高了染料废水的可生化性,为后续的MBR处理创造了条件.     

Biodegradation potential of pure and mixed bacterial cultures for removal of 4-nitroaniline from textile dye wastewater

Environmentally toxic aromatic amines including nitroanilines are commonly generated in dye contaminated wastewater in which azo dyes undergo degradation under anaerobic conditions. The aim of this study was to develop a process for biological treatment of 4-nitroaniline. Three bacteria identified as Acinetobacter sp., Citrobacter freundii and Klebsiella oxytoca were isolated from enrichment cultures of activated sludge on 4-nitroaniline, after which the isolates and the mixed culture were studied to determine optimal conditions for biodegradation. HPLC analyses showed the mixed culture was capable of complete removal of 100 μmol/L of 4-nitroaniline within 72 h under aerobic conditions. There was an inverse linear relationship (R² = 0.96) between the rate of degradation (V) and 4-nitraoaniline concentrations [S] over 100-1000 μmol/L. The bacterial culture was also capable of decolorizing structurally different azo dyes (Acid Red-88, Reactive Black-5, Direct Red-81, and Disperse Orange-3) and also degraded nitrobenzene. Our findings show that enrichment cultures from activated sludge can be effective for the removal of dyes and their toxic intermediates, and that treatment may best be accomplished using an anaerobic-aerobic process.     

厌氧—好氧MBR组合工艺处理蒽醌活性染料废水

采用厌氧-好氧膜生物反应器组合工艺处理蒽醌活性染料废水,考察了处理效果。结果表明,组合工艺对蒽醌染料废水中COD的平均去除率为90％,脱色率平均为48％;当进水染料浓度为100mg／L时系统的脱色率最高（为62％）;投加MnSO4可提高系统的脱色率。     

Bioaugmented membrane bioreactor (MBR) with a GAC-packed zone for high rate textile wastewater treatment

The long-term performance of a bioaugmented membrane bioreactor (MBR) containing a GAC-packed anaerobic zone for treatment of textile wastewater containing structurally different azo dyes was observed. A unique feeding strategy, consistent with the mode of evolution of separate waste streams in textile plants, was adopted to make the best use of the GAC-zone for dye removal. Dye was introduced through the GAC-zone while the rest of the colorless media was simultaneously fed through the aerobic zone. Preliminary experiments confirmed the importance of coupling the GAC-amended anaerobic zone to the aerobic MBR and also evidenced the efficacy of the adopted feeding strategy. Following this, the robustness of the process under gradually increasing dye-loading was tested. The respective average dye concentrations (mg/L) in the sample from GAC-zone and the membrane-permeate under dye-loadings of 0.1 and 1 g/L.d were as follows: GAC-zone (3, 105), permeate (0, 5). TOC concentration in membrane-permeate for the aforementioned loadings were 3 and 54 mg/L, respectively. Stable decoloration along with significant TOC removal during a period of over 7 months under extremely high dye-loadings demonstrated the superiority of the proposed hybrid process.     

Decolorization of an azo dye by unacclimated activated sludge under anaerobic conditions

Studies on the reductive decolorization of a complex azo dye, Reactive Red 3.1, were made as part of the development of a practical approach to better exploit the metabolic potential of biomass in wastewater treatment. Decolorization was achieved at low and variable rates by mixed microbial cultures under various environmental conditions, including low pH and high salt concentration. It was caused by reductive cleavage of the azo bond to yield two aromatic amines. More reliable and effective decolorization rates, of up to 20–30 mg l⁻¹ h⁻¹, were given by unadapted activated sludge, (6 g l⁻¹) incubated with 400 mg l⁻¹ of Reactive Red 3.1 under anaerobic conditions. Decolorization also occurred best in static conditions.     

Aerobic degradation of acid orange 7 in a vertical-flow constructed wetland

Biological, aerobic degradation of an azo dye and of the resultant, recalcitrant, aromatic amines in a constructed wetland (CW) was demonstrated for the first time. A vertical-flow CW, planted with Phragmites sp. was fed with 127 mg l⁻¹ of acid orange 7 (AO7) at hydraulic loads of 28, 40, 53 and 108 l m⁻²day⁻¹. Color removal efficiencies of up to 99% clearly demonstrate cleavage of the azo bond, also confirmed by the similar AO7 removal and SO₄²⁻ release rates revealing that adsorption onto the matrix was constant. The positive redox potential at the outlet demonstrates that aerobic conditions were present. Chemical oxygen demand and total organic carbon removal efficiencies of up to 93% were also indicative of AO7 mineralization. The degradation of sulfanilic acid was confirmed by the presence of NO₃⁻, SO₄²⁻ and secondary metabolites, which suggest at least two degradation pathways leading to a common compound, 3-oxoadipate.     

Optimisation of process parameters for bioreduction of azo dyes using Bacillus firmus under batch anaerobic condition

A new dye decolourising bacterial strain was isolated from textile wastewater and identified as Bacillus firmus. The study indicated that the bacterium could efficiently decolourise different azo dyes under static culture conditions. Characterisation of the efficiency of azo dye reduction by this isolate using both spectral and HPLC analysis was found to be a function of process parameters which include dye concentration, culture broth pH, incubation temperature, aeration as well as nitrogen source. For decolourisation, the optimal pH and temperature were 7–8 and 20–35°C respectively, while remarkable dye degradation was obtained within 18 h for dye concentrations below 100 mg L^?1. With the addition of yeast extract and under optimal conditions, dye reduction was enhanced and complete colour removal was achieved within 12 h. Colour removal was shown to be due to biodegradation rather than adsorption of dyes on bacterial cells. This study confirms the ability of the new dye‐degrading strain, Bacillus firmus, to decolourise and degrade different azo dyes and highlights its high biotechnology potential for the eco‐friendly treatment of textile wastewater when optimal conditions are applied.     

物化/生化集成的生物造粒流化床处理污水技术

介绍了一种将上向流造粒流化床固液分离技术与好氧生物降解技术高度集成的生物造粒流化床处理污水新工艺,从其除污效率、造粒颗粒污泥的物理化学性质和形态、颗粒污泥的微生物特性等方面介绍了该工艺的特点.研究表明,生物造粒流化床在总水力停留时间仅为33min的条件下能同时完成混凝造粒、生物降解、固液分离等多个过程,对SS、COD、TP和TN的去除率可分别达到95%、90%、94%和40%左右,达到了与常规活性污泥法相当的二级处理效果.     

Degradation of a textile reactive Azo dye by a combined chemical-biological process: Fenton's reagent-yeast

This work presents the results of our studies on the decolorization of aqueous azo dye Reactive black 5 (RB5) solution combining an advanced oxidation process (Fenton's reagent) followed by an aerobic biological process (mediated by the yeast Candida oleophila). Under our conditions, initial experiments showed that Fenton's process alone, as well as aerobic treatment by C. oleophila alone, exhibited the capacity to significantly decolorize azo dye solutions up to 200 mg/L, within about 1 and 24h, respectively. By contrast, neither Fenton's reagent nor C. oleophila sole treatments showed acceptable decolorizing abilities for higher initial dye concentrations (300 and 500 mg/L). However, it was verified that Fenton's reagent process lowered these higher azo dye concentrations to a value less than 230 mg/L, which is apparently compatible with the yeast action. Therefore, to decolorize higher concentrations of RB5 and to reduce process costs the combination between the two processes was evaluated. The final decolorization obtained with Fenton's reagent process as primary treatment, at 1.0 x 10(-3)mol/L H(2)O(2) and 1.0 x 10(-4)mol/L Fe(2+), and growing yeast cells as a secondary treatment, achieves a color removal of about 91% for an initial RB5 concentration of 500 mg/L.     

Kinetics of a reactive dye adsorption onto dolomitic sorbents

A novel wastewater treatment technique has been investigated, for reactive dye removal, in batch kinetic systems. These experimental studies have indicated that charred dolomite has the potential to act as an adsorbent for the removal of Brilliant Red reactive dye from aqueous solution. The effect of initial dye concentration, adsorbent mass:liquid volume ratio, and agitation speed on dye removal have been determined with the experimental data mathematically described using empirical external mass transfer and intra-particle diffusion models. The experimental data show conformity with an adsorption process, with the removal rate heavily dependent on both external mass transfer and intra-particle diffusion.     

Further treatment of decolorization liquid of azo dye coupled with increased power production using microbial fuel cell equipped with an aerobic biocathode

A microbial fuel cell (MFC) incorporating a recently developed aerobic biocathode is designed and demonstrated. The aerobic biocathode MFC is able to further treat the liquid containing decolorization products of active brilliant red X-3B (ABRX3), a respective azo dye, and also provides increased power production. Batch test results showed that 24.8% of COD was removed from the decolorization liquid of ABRX3 (DL) by the biocathode within 12 h. Metabolism-dependent biodegradation of aniline-like compound might be mainly responsible for the decrease of overall COD. Glucose is not necessary in this process and contributes little to the COD removal of the DL. The similar COD removal rate observed under closed circuit condition (500 Ω) and opened circuit condition indicated that the current had an insignificant effect on the degradation of the DL. Addition of the DL to the biocathode resulted in an almost 150% increase in open cycle potential (OCP) of the cathode accompanied by a 73% increase in stable voltage output from 0.33 V to 0.57 V and a 300% increase in maximum power density from 50.74 mW/m² to 213.93 mW/m². Cyclic voltammetry indicated that the decolorization products of the ABRX3 contained in the DL play a role as redox mediator for facilitating electron transfer from the cathode to the oxygen. This study demonstrated for the first time that MFC equipped with an aerobic biocathode can be successfully applied to further treatment of effluent from an anaerobic system used to decolorize azo dye, providing both cost savings and high power output.     

应用工艺智能优化控制系统降低污水厂能耗

生物工艺智能优化系统（BIOS）是一个前馈优化系统，通过获得A／O工艺实时的在线数据（如氨氮、硝酸盐氮、进水流量、混合液悬浮物浓度），BIOS系统不断进行模拟计算，然后按照生物反应器进水的污染物负荷状况来提供最佳的DO设定值；同时为达到最佳的TN去除率，BIOS系统还对好氧区回流至缺氧区的内回流比（IRQ）进行了优化。BIOS系统在美国康涅狄格州En-field污水厂的实际应用情况表明，该系统能提高脱氮效率36％，同时降低曝气量19％。     

新型一体化生物反应器的同步脱氮除磷影响因素研究

为了提高对污水的处理效能,设计了一种新型一体化生物反应器并采用其处理生活污水,研究了DO和HRT对同步脱氮除磷效果的影响,并探讨了其实现机理。试验结果表明：在进水COD为290～510mg／L、MLSS为2500mg／L、污泥龄为15d以及好氧区和缺氧区的溶解氧分别为2mg／L和0．2mg／L时,系统的脱氮除磷效果较好,对TN、TP的去除率分别可达80％和90％,DO过高或过低都会影响同步脱氮除磷的效果。控制DO为最优值,并保持其他操作条件相同,当HRT为12h时对总氮和总磷的去除率均在80％以上,随着HRT的延长,同步脱氮除磷效果反而下降。该一体化反应器集厌氧、缺氧和好氧区为一体,在一定的运行条件下能够实现同步脱氮除磷,是处理生活污水的有效方法。     

Assessment of full-scale natural systems for the removal of PPCPs from wastewater in small communities

This study assessed the ability to remove pharmaceuticals and personal care products (PPCPs) of three different full-scale hybrid pond-constructed wetlands and a conventional wastewater treatment plant (WWTP). The four systems were fed with primary-treated urban wastewaters. The three hybrid systems consisted of several different subsystems (ponds, surface flow constructed wetlands and horizontal subsurface flow constructed wetlands) connected in series, and their PPCP degradation efficiency was monitored. In addition, the enantiomeric behaviour of ibuprofen was studied in all the subsystems. The hybrid systems were at least as efficient in PPCP removal as the WWTP, removal efficiencies mainly exceeding 70%. Moreover, enantiomeric analysis indicates that ibuprofen removal followed a predominantly aerobic and microbiological pathway. Constructed wetlands and ponds are therefore successful technologies for removing PPCPs from wastewater and the most significant removal process in these systems is biologically mediated.     

小氮肥企业高氨氮废水处理的试验研究

针对小氮肥厂生产废水的排放现状及其对城市污水处理厂的影响 ,在试验的基础上提出了处理高含氨氮废水的空气吹脱—好氧硝化处理工艺 .空气吹脱可有效地去除解吸液中的氨氮 ,氨氮浓度由 1869.3mg/L降至 40 8.3mg/L ,去除率为 78% ;好氧生物硝化可有效地去除混合生产废水中的氨氮 ,氨氮浓度由 2 41mg/L降低为 2 3 .2mg/L ,去除率达 90 % ,达到国家二级排放标准     

一体式膜生物反应器同步硝化反硝化性能研究

构建了气升循环一体式膜生物反应器,将其用于处理城市污水,并对其同步硝化反硝化(SND)的形成过程进行了研究。结果表明,反应器内存在明显的好氧区和厌氧区,并利用曝气推动力实现硝化液在各区间的循环,能够形成良好的硝化和反硝化过程;在反应器结构一定的条件下,曝气强度成为制约溶解氧大小和分布的最主要因素,过大或过小的曝气强度对TN的去除都是不利的,当曝气强度控制在50~70 m3/(m2.h)时,系统对TN的去除效果最好,去除率为48.1%~54.0%,实现了较好的同步硝化反硝化效果。     

A/O-MBR处理低浓度生活污水的试验研究

针对传统活性污泥法处理低浓度生活污水难度大的问题,采用缺氧-好氧膜生物反应器(A/O-MBR)处理该类污水,并考察了其处理效果.结果表明,在污泥浓度为4 000～6 000mg/L、HRT为19.2 h、好氧段溶解氧浓度为1.5～2.5 mg/L、污泥回流比为200%～300%的条件下,A/O-MBR对COD和氨氮的去除效果良好,平均去除率分别为92.2%和95.9%.在无排泥的情况下,系统连续运行近100d,出水水质稳定.     

不同工况下膜—SBR工艺的除污效能研究

将一体式膜生物反应器与序批式活性污泥法相结合而构建了M-SBR工艺.采用该工艺处理模拟生活污水,通过调节反应器的厌氧、好氧和缺氧时间比例,使系统分别按照A0-MSBR和AOA-MSBR的方式运行,考察了在相同操作条件下,系统对COD、氮、磷的去除效果.试验结果表明:AOA-MSBR工艺比A0-MSBR工艺具有更好的同步脱氮除磷效果,其对COD的平均去除率达到了98.5%,对氨氮的平均去除率达到了90.3%,对总氮的平均去除率达到了89.5%,对总磷的平均去除率为88.5%.     

Fate of hazardous aromatic substances in membrane bioreactors

In this work, the removal of hazardous aromatic compounds was investigated in two types of membrane bioreactors (MBRs), based on cross-flow and semi dead-end filtration systems. BTEX and PAH were efficiently eliminated from wastewater during treatment via a membrane bioreactor (90-99.9%) but non-biotic processes, i.e. volatilisation and sorption, contributed significantly. The semi dead-end MBR showed slightly better removal efficiencies than the cross-flow MBR. However, non-biotic processes were more significant in the first process and, finally, degradation rates were higher in the cross-flow MBR. Higher degradation rates were explained by a higher bio-availability of pollutants. Differences in shear stress imposed in cross-flow and semi dead-end filtration systems radically modify the sludge morphology. High shear stress (cross-flow filtration) generates dispersed bacteria and larger quantities of dissolved and colloidal matter. Sorption of hydrophobic compounds (PAHs) on suspended solid was less marked in disaggregated sludge. The results suggest new strategies for improving micro-pollutant degradation in MBRs.