焦化废水处理过程中特征有机污染物组成及降解特性分析

为了解焦化废水中特征有机污染物组成及其在生物流化床工艺各个阶段的降解特性,采用全二维气相色谱(GC×GC)技术,对不同处理阶段的焦化废水进行了检测,解析了其特征有机污染物的组成和降解规律.结果 显示,焦化废水中主要存在有十三大类的特征有机污染物,经两级缺氧和两级好氧处理后所有物质都有所降解但发生的阶段不同,酚类、吡啶类、有机腈类、萘啶类、三唑类、吲哚类物质的降解在缺氧和好氧阶段都有发生,但是喹啉类、咪唑类、酰胺类、酮类、有机胺类的降解主要发生在好氧阶段,明确了各物质在缺氧好氧阶段的不同降解特性.     

复合厌氧反应器的生产性快速启动研究

针对复合厌氧反应器处理高浓度难降解有机废水如何创造生产性快速启动条件及反应器的有效控制进行了相关研究。试验分别采用好氧青霉素发酵残渣和好氧活性污泥为接种污泥启动复合厌氧反应器 ,生产性中试规模 5 0m3 /d。试验表明 ,青霉素发酵残渣启动厌氧反应器在经济上和技术上都是可行的 ,启动周期短 ,试验系统表现出很好的生物降解性和抗冲击负荷能力     

好氧颗粒污泥处理高浓度及难降解废水研究进展

好氧颗粒污泥以其在反应器中污泥沉降速度快、泥水分离简单、污泥浓度高,能够同时实现脱氮除磷等特点成为目前污(废)水处理领域的研究热点之一。对好氧颗粒污泥在高浓度有机废水及难降解废水(硝基苯废水、苯酚废水、氯酚废水、苯胺和氯苯胺废水、含盐废水、染料废水)处理中的研究现状进行综述,重点探讨了好氧颗粒污泥处理该类物质的影响因素、去除机制及其微生物特性等,指出其在难降解废水处理方面具有良好的应用前景。     

微生物电解池改善垃圾焚烧渗沥液厌氧处理性能研究

垃圾焚烧渗沥液是一种含有多种污染组分的高浓污水,在渗沥液处理中常采用厌氧消化去除有机污染物。采用试验研究微生物电解池用于垃圾焚烧渗沥液处理的性能,试验结果表明：相比常规厌氧反应器,微生物电解池能够在更高的有机负荷下正常运行,具有更强的有机负荷耐受性和适应性;微生物电解池能够提高渗沥液中腐殖质等大分子难降解有机物的降解率,降低其在厌氧出水中的含量,有利于后续处理单元稳定运行;微生物电解池能够提高甲烷产量和甲烷产率,具有良好的能源回收潜能。     

微生物在湿地氮循环系统的效应分析

从湿地植物根区微环境研究出发,分析了湿地系统氮循环中微生物效应及其湿地植物为微生物生长提供的微生态系统功能。指出在湿地系统氮循环中的微生物过程(包括亚硝化、硝化、反硝化和异化作用等)是氮降解的主要过程,植物对营养物质的直接去除所占比例很小,但植物的生理特性从不同途径影响不同氮化合物的微生物转化。厌氧氨氧化过程是一种氮素转化的新途径,能同时将两种氮污染物(氨氮和亚硝酸氮)转化成气态氮,从而高效地减缓氮污染问题。好氧/厌氧界面在湿地植物根区微环境中的广泛存在及有关研究成果,说明了湿地氮循环系统中厌氧氨氧化过程存在的可能性。     

磁化—厌氧复合处理有机污水的试验研究

目前，磁化对好氧生物降解有机物的研究较多。在厌氧条件下，采用不同磁场强度，对不同种类的有机污水进行实验分析；结果表明，在厌氧条件下，磁处理对提高水中有机物分解更为显著；在实验的基础上，分析了磁处理对厌氧生物降解有机物的影响因素，并探讨了磁化一厌氧生物降解有机物的机理。     

PTA废水生物处理工艺综述

PTA废水是由对二甲苯(PX)生产PTA过程中产生的排水。废水成分复杂,含大量芳香烃有机物,包括难降解有机物TA和甲基苯甲酸。分析了PTA废水中的芳香烃有机物好氧降解、厌氧降解机理以及TA降解机理。分析结果表明:芳香烃有机物好氧降解速率明显高于厌氧降解速。目前,对于PTA废水处理研究集中在好氧处理和厌氧处理工艺上,重点介绍了PTA废水厌氧、好氧及厌氧-好氧处理的几种工艺及其处理效果。综合投资、能耗、污泥量、操作、处理效率等多种因素,总结出PTA废水处理的最优工艺为厌氧-好氧处理工艺,常用工艺组合包括上旋流厌氧反应器+两级好氧、水解+A/O、两级A/O等。并讨论分析了重金属钴、锰,营养物质N,P,Mg,Fe等以及温度、pH对PTA废水处理效率的影响。同时,展望了PTA废水的研究发展趋势。     

复合生物反应器对焦化废水中典型污染物处理特性的研究

采用厌氧缺氧好氧工艺，并在好氧段投入球形填料形成复合反应器处理焦化废水，重点对好氧复合反应器中两相污泥的污染物降解活性进行了比较。试验结果表明好氧复合反应器中附着相污泥浓度高于悬浮相污泥浓度；附着相污泥对焦化废水中苯酚、喹啉和氨氮三种代表性污染物的降解能力和抗抑制性能力均高于悬浮相污泥。     

含沙量对水体耗氧有机污染物降解耗氧影响

在泥沙存在情况下,水体中的耗氧有机污染物的降解耗氧规律与清水中有很大的差异。从水体耗氧有机物降解反应动力学和溶解氧反应动力学方程出发,考虑泥沙对耗氧有机污染物降解的影响,得出了耗氧有机物降解过程耗氧量随时间变化表达式。通过室内实验研究了含沙量对耗氧有机污染物的耗氧规律的影响,利用耗氧量随时间表达式对实验数据进行分析,得出了泥沙影响下的耗氧有机污染物耗氧速率常数与含沙量的一般规律。结果表明,泥沙对耗氧有机污染物降解耗氧过程符合一级动力学反应,且耗氧速率常数随含沙量的增大而增大,由泥沙存在引起的溶解氧衰减速率常数与含沙量之间存在非线线的函数关系。     

典型污染场地含水层天然净化能力溶质模拟研究

根据典型石油类污染场地岩性、水文地质等特征,在长期观测、抽水试验及弥散试验等资料搜集与分析基础上,通过水流模型验证,构建了地下水水流运动及溶质迁移的数值模型。选取苯系物(BTEX)作为模拟因子,运用GMS软件中MT3DMS模块模拟地下水对流-弥散溶质迁移过程,运用RT3D模块模拟研究了地下水中移动、非移动的多种微生物共存的有机污染物生物降解过程。结果表明,生物降解化学反应具有明显的降低污染物峰值的作用,而研究区存在大量的好氧微生物作用和反硝化作用,据此提出可以采用原位生物修复技术来治理石油污染。     

Biodegradation of chlorobenzene in a constructed wetland treating contaminated groundwater.

Monochlorobenzene (MCB) is an important groundwater contaminant world-wide. In this study, a horizontal subsurface flow constructed wetland with an integrated water compartment was fed with MCB contaminated groundwater originating from the local aquifer. Analysis of spatial concentration dynamics of MCB and oxygen was combined with isotope composition analysis of MCB for assessing in situ biodegradation. Removal of MCB was most effective in the upper layer of the soil filter, reaching up to 77.1%. Trace oxygen concentrations below 0.16 mg L(-1) were observed throughout the wetland transect, suggesting a considerable limitation of aerobic microbial MCB degradation. Enrichment of 13C in the residual MCB fraction at increasing distance from the inflow point indicated microbial MCB degradation in the wetland. The observed isotope shift was higher than expected for aerobic MCB degradation and thus pointed out a significant contribution of an anaerobic degradation pathway to the overall biodegradation.     

Biological treatment of thin-film transistor liquid crystal display (TFT-LCD) wastewater

The amount of pollutants produced during manufacturing processes of TFT-LCD (thin-film transistor liquid crystal display) substantially increases due to an increasing production of the opto-electronic industry in Taiwan. The total amount of wastewater from TFT-LCD manufacturing plants is expected to exceed 200,000 CMD in the near future. Typically, organic solvents used in TFT-LCD manufacturing processes account for more than 33% of the total TFT-LCD wastewater. The main components of these organic solvents are composed of the stripper (dimethyl sulphoxide (DMSO) and monoethanolamine (MEA)), developer (tetra-methyl ammonium hydroxide (TMAH)) and chelating agents. These compounds are recognized as non-or slow-biodegradable organic compounds and little information is available regarding their biological treatability. In this study, the performance of an A/O SBR (anoxic/oxic sequencing batch reactor) treating synthetic TFT-LCD wastewater was evaluated. The long-term experimental results indicated that the A/O SBR was able to achieve stable and satisfactory removal performance for DMSO, MEA and TMAH at influent concentrations of 430, 800, and 190 mg/L, respectively. The removal efficiencies for all three compounds examined were more than 99%. In addition, batch tests were conducted to study the degradation kinetics of DMSO, MEA, and TMAH under aerobic, anoxic, and anaerobic conditions, respectively. The organic substrate of batch tests conducted included 400 mg/L of DMSO, 250 mg/L of MEA, and 120 mg/L of TMAH. For DMSO, specific DMSO degradation rates under aerobic and anoxic conditions were both lower than 4 mg DMSO/g VSS-hr. Under anaerobic conditions, the specific DMSO degradation rate was estimated to be 14 mg DMSO/g VSS-hr, which was much higher than those obtained under aerobic and anoxic conditions. The optimum specific MEA and TMAH degradation rates were obtained under aerobic conditions with values of 26.5 mg MEA/g VSS-hr and 17.3 mg TMAH/g VSS-hr, respectively. Compared to aerobic conditions, anaerobic biodegradation of MEA and TMAH was much less significant with values of 5.6 mg MEA/g VSS-hr and 0 mg TMAH/g VSS-hr, respectively. In summary, biological treatment of TFT-LCD wastewater containing DMSO, MEA, and TMAH is feasible, but appropriate conditions for optimum biodegradation of DMSO, MEA, and TMAH are crucial and require carefully operational consideration.     

Biodegradation of phenol at low temperature using two-phase partitioning bioreactors.

Two-phase partitioning bioreactors offer many advantages for the removal of toxic pollutants. In particular, such systems can be loaded with very large quantities of pollutants without risks of microbial inhibition, they are self-regulated and they prevent the risks of hazardous pollutant volatilisation during aerobic treatment. However, their potential has never been tested at low temperatures. Phenol biodegradation by a cold adapted Pseudomonas strain was therefore tested at 14 or 4 degrees C using 2-undecanone, diethyl sebacate or 2-decanone as organic phases in a two-phase partitioning bioreactor. The three solvents were biocompatible at 14 degrees C but evidence was found that diethyl sebacate was biodegraded by the bacteria and this solvent was not tested further. Although only 2-decanone was suitable at 4 degrees C, phenol biodegradation was more efficient in 2-undecanone at 14 degrees C, reaching a maximum volumetric rate (based on the volume of aqueous phase) of approximately 1.94 g/L.day after 47 h of cultivation. In 2-decanone at 14 degrees C, evidence was found that phenol degradation was limited by the release of biosurfactants, which increased the solubility and toxicity of the solvent in the aqueous phase inhibiting microbial activity. This study therefore shows that pollutant removal at low temperature is feasible but that the production of biosurfactants can have a negative impact on the process and must be taken into consideration when selecting the organic solvent. Future work should therefore focus on the selection of solvents suitable for use at temperatures below 14 degrees C.     

Anaerobic/aerobic treatment of colorants present in textile effluents.

The operation of an anaerobic/aerobic process used to degrade the colorants present in textile wastewater is presented. The objective is to produce water that can be reused. Two particular cases were studied: the degradation of a synthetic wastewater containing the colorant disperse blue 79 (DB79) as a model compound and a real textile effluent containing reactive azo dyes. The biodegradation was achieved using a single tank operated as sequencing batch reactor. It was observed that the DB79 was biotransformed to amines in the anaerobic stage decolorizing the wastewater. The amines formed were subsequently mineralized in the aerobic phase. An increase of toxicity was observed in the anaerobic stage due to the amines formation, but the wastewater was detoxified after the aerobic treatment. Removal efficiencies of DB79 around 92% were observed after the treatment. Around 96% of the initial color of the real wastewater was effectively removed. It was observed that the biomass pre-acclimatized to the degradation of DB79 was more effective for the color removal than a freshly inoculum used.     

Assessment of microbial natural attenuation in groundwater polluted with gasworks residues.

Intrinsic biodegradation, representing the key process in Natural Attenuation, was examined at a tar-oil polluted disposal site. Methods to assess microbial natural attenuation of BTEX and PAH included analysis of groundwater hydrochemistry, pollutant profiles, composition of the microflora, and microcosm studies. In the polluted groundwater downgradient the disposal site, oxygen and nitrate were only available adjacent to the groundwater table and at the plume fringes. In the anaerobic core of the plume, a sequence of predominating redox zones (methanogenic, sulphate-reducing, Fe(III)-reducing) was observed. Changing pollutant profiles in the plume indicated active biodegradation processes, e.g. biodegradation of toluene and naphthalene in the anaerobic zones. High numbers of microorganisms capable of growing under anaerobic conditions and of aerobic pollutant degrading organisms confirmed the impact of biodegradation at this site. In microcosm studies, the autochthonous microflora utilised toluene, ethylbenzene, and naphthalene under sulfate- and Fe(III)-reducing conditions. Additionally, benzene and phenanthrene were degraded in the presence of Fe(III). Under aerobic conditions, all BTEX and PAH were rapidly degraded. The microcosm studies in particular were suitable to examine the role of specific electron acceptors, and represented an important component of the multiple line of evidence concept to assess natural attenuation.     

Biodegradation of Pharmaceutical Compounds and their Occurrence in the Jordan Valley

In particular in arid regions the reuse of waste water and aquifer recharge is an important issue. Elimination of persistent emerging pollutants represents a key factor in integrated water resources management, and identifying suitable treatment processes to eliminate such compounds becomes inevitably necessary. It is the objective of this study (1) to assess the occurrence of emerging pollutants in the Jordan Valley and (2) to review and examine the biodegradability of selected key compounds. Among the most frequently detected compounds during a sampling campaign in 2007 were pharmaceutical residues such as carbamazepine, diclofenac, or naproxen, and X-ray contrast agents such as diatrizoic acid and iopromide, all typically found in Europe and the USA as well. To gain further insight into elimination processes, biodegradation studies were conducted with batch tests and flow-through soil columns under unsaturated, aerobic conditions. Results demonstrated biodegradation for pharmaceutical residues such as ibuprofen, diclofenac and bezafibrate. The degradation rate was faster in treated waste water as compared to raw waste water, most probably due to competing substrate consumption in raw waste water. The antiepileptic carbamazepine showed no degradation in the batch tests and only moderate removal during soil passage, probably due to sorption. The results of this study and previously published data emphasize the need for further studies under more defined conditions to elucidate the specific conditions under which biodegradation of emerging pollutants proceeds.     

Biodegradation of a variety of bisphenols under aerobic and anaerobic conditions.

There is a group of compounds structurally similar to bisphenol-A (BPA), namely bisphenols (BPs), and some of them are considered to be able to partially replace BPA. In order to assess their biodegradability in the aquatic environment, a variety of BPs; BPA, bis(4-hydroxyphenyl)methane (BPF), bis(4-hydroxyphenyl)ethane (BPE), 2,2-bis(4-hydroxy-phenyl)butane (BPB), 2,2-bis(4- hydroxy-3-methylphenyl)propane (BPP), bis(4-hydroxyphenyl)sulfone (BPS), thiodiphenol (TDP) and 4,4'-dihydroxybenzophenone (HBP); were subjected to biodegradation tests under both aerobic and anaerobic conditions. For the aerobic degradation test, a kind of river-die-away method using several river water samples was used, while pond sediments were used for the anaerobic degradation tests in sealed anoxic bottles. As a whole, the examined BPs could be ranked by their biodegradability under aerobic conditions; BPF, HBP > > BPA > BPP > BPE > BPB > TDP > > BPS. On the other hand, the tendency for the anaerobic biodegradability was; BPF > HBP > BPS, BPA, TDP > BPE > BPB. From the viewpoint of biodegradability, BPF seems to be more environmentally-friendly than BPA and, therefore, may be a candidate to replace BPA for reducing the environmental risks.     

Study of a three-stage fluidized bed process treating acrylic synthetic-fiber manufacturing wastewater containing high-strength nitrogenous compounds.

Polyacrylonitrile (PAN) is one of the major synthetic fibers commonly used in the mass production of clothing. The chemical synthesis of PAN is carried out by polymerization of the acrylonitrile (AN) monomers with co-monomers such as vinyl acetate, methyl acrylate and cyclohexyl acrylate. Using water quality analysis of the PAN wastewater, high concentration of organic nitrogen was found and the TKN/COD ratios achieved were 0.15-0.26, indicating the complicated biodegradation characteristics for the PAN wastewater. In order to enhance biodegradation of nitrogenous compounds in PAN wastewater, a combined three-stage process of thermophilic anaerobic/anoxic denitrification/aerobic nitrification fluidized bed reactors was employed. The results indicated that the concentration of effluent in the three-stage process of OD and organic nitrogen was 175 mg/L and 13 mg/L, respectively. Furthermore, molecular biotechnology was applied to study the microbial population in the thermophilic anaerobic fluidized bed reactor. From the results of denaturing gradient gel electrophoresis, the diversity of PAN-degrading bacteria would change in different volumetric loading. Furthermore, the bacteria communities in the thermophilic anaerobic fluidized bed reactor were also studied by fluorescence in situ hybridization and confocal laser scanning microscopy. Alpha and delta-Proteobacteria were dominant in the bacteria population, and some high G+C content bacteria and Clostridium could be characterized in this system.     

Modelling as a tool when interpreting biodegradation of micro pollutants in activated sludge systems.

The aims of the present work were to improve the biodegradation of the endocrine disrupting micro pollutant, bisphenol A (BPA), used as model compound in an activated sludge system and to underline the importance of modelling the system. Previous results have shown that BPA mainly is degraded under aerobic conditions. Therefore the aerobic phase time in the BioDenitro process of the activated sludge system was increased from 50% to 70%. The hypothesis was that this would improve the biodegradation of BPA. Both the influent and the effluent concentrations of BPA in the experiment dropped significantly after increasing the aerobic time. From simulations with a growth-based biological/physical/chemical process model it was concluded that although the simulated effluent concentration of BPA was independent of the influent concentration at steady-state, the observed drop in effluent concentrations probably was caused by either a larger specific biomass to influent BPA ratio, improved biodegradation related to the increased aerobic phase time, or a combination of the two. Thereby it was not possibly to determine if the increase in aerobic phase time improved the biodegradation of BPA. The work underlines the importance of combining experimental results with modelling when interpreting results from biodegradation experiments with fluctuating influent concentrations of micro pollutants.