Evaluation of performance and microbial ecology of sequencing batch reactor and membrane bioreactor treating thin-film transistor liquid crystal display wastewater

In Taiwan, a substantial amount of thin-film transistor liquid crystal display (TFT-LCD) wastewater is produced daily due to an increasing production of the opto-electronic industry in recent years. The main components of TFT-LCD wastewater include dimethyl sulphoxide (DMSO), monoethanolamine (MEA), and tetra-methyl ammonium hydroxide (TMAH), which are recognized as non-or slow-biodegradable organic compounds and limited information is available regarding their biological treatablility. This study was conducted to evaluate the long-term performance of two bioreactors, anaerobic-aerobic (A/O) sequencing batch reactor (SBR) and aerobic membrane bioreactor (MBR), treating synthetic TFT-LCD wastewater containing DMSO, MEA, and TMAH with different loadings. For the A/O SBR, the influent wastewater was composed of 800 mg MEA/L, 430 mg DMSO/L, and 90 mg TMAH/L, respectively. After reaching steady-state, SBR was able to achieve more than 99% degradation efficiencies for the three compounds examined. For the case of aerobic MBR, the influent wastewater was composed of 550 mg MEA/L, 270 mg DMSO/L, and 330 mg TMAH/L, respectively, and degradation efficiencies for the three compounds achieved more than 99%. Although both different reactors shared similar and satisfactory degradation efficiencies for DMSO, MEA, and TMAH, the microbial ecology of these two reactors, as elucidated with molecular methods, was apparently different. The 16S rDNA-based cloning/sequencing results indicated that the dominant sequences retrieved from the aerobic MBR, including Hyphomicrobium denitrificans, Hyphomicrobium zavarzinii, Rhodobacter sp., and Methyloversatilis universalis, showed a clear linkage to their physiological properties of DMSO and TMAH degradation. On the other hand, Zoogloea sp., Chlorobium chlorochromatii, Agricultural soil bacterium, and Flavosolibacter ginsengiterrae were proliferated in the A/O SBR Run1, while Thiobacillus sp., Nitrosomonas sp., Thauera aromatica and Azoarcus sp. became dominant in Run2. Furthermore, the sequences retrieved from different reactors were used to establish the terminal restriction fragment length polymorphism (TRFLP) fingerprint methodology for monitoring the dynamics of dominant degrading bacteria in the aerobic MBR treating TFT-LCD wastewater.     

Combined membrane bioreactor (MBR) and reverse osmosis (RO) system for thin-film transistor-liquid crystal display TFT-LCD, industrial wastewater recycling.

In TFT-LCD industry, water plays a variety of roles as a cleaning agent and reaction solvent. As good quality water is increasingly a scarce resource and wastewater treatment costs rises, the once-through use of industrial water is becoming uneconomical and environmentally unacceptable. Instead, recycling of TFT-LCD industrial wastewater is become more attractive from both an economic and environmental perspective. This research is mainly to explore the capacity of TFT-LCD industrial wastewater recycling by the process combined with membrane bioreactor and reverse osmosis processes. Over the whole experimental period, the MBR process achieved a satisfactory organic removal. The COD could be removed with an average of over 97.3%. For TOC and BOD5 items, the average removal efficiencies were 97.8 and 99.4% respectively. The stable effluent quality and satisfactory removal performance were ensured by the efficient interception performance of the UF membrane device incorporated with biological reactor. Moreover, the MBR effluent did not contain any suspended solids and the SDI value was under 3. After treatment of RO, excellent water quality of permeate were under 5 mg/l, 2.5 mg/l and 150 micros/cm for COD, TOC and conductivity respectively. The treated water can be recycled for the cooling tower make-up water or other purposes.     

重金属废水生物处理技术

主要从生物法去除废水中重金属的原理,重金属废水生物处理技术,及重金属废水生物处理的影响因素等方面,综述了国内外有关重金属废水生物处理技术的研究成果,并介绍了重金属废水生物处理的工程应用,提出关于重金属废水生物处理的研究方向。     

Use of iron(VI) and iron(V) in water and wastewater treatment.

Fe(VI) (Fe(VI)O4(2-)) and Fe(V) (Fe(V)O4(3-)) have high oxidizing power, selectivity, and upon decomposition produce a non-toxic by-product, Fe(III), which makes them potential oxidants in water and wastewater treatment. Rates of oxidation increase with a decrease in pH and are related to protonation of Fe(VI)O4(2-) and Fe(V)O4(3-). Oxidation of sulfur- and nitrogen-containing pollutants by Fe(VI) can be accomplished in seconds to minutes with formation of non-hazardous products. Fe(VI) can easily oxidize the amino acid components of microcystins and is a suitable disinfectant for detoxifying toxins in water. The oxidation of pollutants and amino acids with Fe(V) is 3-5 orders of magnitude faster than with Fe(VI). The use of ionizing radiation and photocatalytic techniques in the presence of Fe(VI) results in Fe(V) formation and may have synergistic effects on the oxidation of pollutants and removal of toxins in water and wastewater. This paper summarizes the results of multi-functional properties of Fe(VI) and Fe(V) to treat water and wastewater.     

Integrated biological (anaerobic-aerobic) and physico-chemical treatment of baker's yeast wastewater.

The UASB reactor (35 degrees C) was quite efficient for removal of bulk COD (52-74%) from simulated (on the basis of cultivation medium from the first separation process) general effluent of baker's yeast production (the average organic loading rates varied from 8.1 to 16 g COD/l/d). The aerobic-anoxic biofilter (19-23 degrees C) can be used for removal of remaining BOD and ammonia from anaerobic effluents; however, it suffered from COD-deficiency to fulfil denitrification requirements. To balance COD/N ratio, some bypass (approximately 10%) of anaerobically untreated general effluent should be added to the biofilter feed. The application of iron (III)-, aluminium- or calcium-induced coagulation for post-treatment of aerobic-anoxic effluents can fulfil the limits for discharge to sewerage (even for colour mainly exerted by hardly biodegradable melanoidins), however, the required amounts of coagulants were relatively high.     

利蒙(LLMO)浓缩微生物菌在江西赛得利粘胶化纤废水治理中的应用

研究了利用投加利蒙菌对赛得利污水厂生化池进行改进,以期提高出水的CODC r与SS去除率,稳定出水水质。实验结果表明,利蒙菌在对粘胶化纤废水生化处理上的改进是可行的,对废水中CODC r、SS的平均去除率可比未投加提高56%、44%,其出水水质良好、稳定,其中CODC r<40 m g/L、SS<50 m g/L。     

A dispersed-ozone flotation (DOF) separator for tertiary wastewater treatment.

A dispersed-ozone flotation (DOF) separator was devised for a pilot study of tertiary wastewater treatment for re-use purposes. As a compact device combining coagulation, ozonation and flotation in an integrated unit, the DOF separator achieved a very high removal of SS, TOC, UV254 and colour, as well as effective inactivation of coliform and total bacteria within a short hydraulic retention time of 30 min. The finished water quality is comparable to or better than that by a conventional tertiary treatment process using coagulation, sedimentation, filtration and chlorine disinfection, and meets the quality standards for non-drinkable domestic reuse.     

Biological sludge solubilisation for reduction of excess sludge production in wastewater treatment process.

A novel sludge disintegration system (JFE-SD system) was developed for the reduction of excess sludge production in wastewater treatment plants. Chemical and biological treatments were applied to disintegrate excess sludge. At the first step, to enhance biological disintegration, the sludge was pretreated with alkali. At the second step, the sludge was disintegrated by biological treatment. Many kinds of sludge degrading microorganisms integrated the sludge. The efficiency of the new sludge disintegration system was confirmed in a full-scale experiment. The JFE-SD system reduced excess sludge production by approximately 50% during the experimental period. The quality of effluent was kept at quite a good level. Economic analysis revealed that this system could significantly decrease the excess sludge treatment cost.     

Evaluation of a hybrid vertical membrane bioreactor (HVMBR) for wastewater treatment

A new hybrid membrane bioreactor (HMBR) has been developed to obtain a compact module, with a small footprint and low requirement for aeration. The aim of this research was to assess its performance. The system consists of a single vertical reactor with a filtration membrane unit and, above this, a sponge fixed bed as support medium. The aeration system is located under the membrane unit, allowing for membrane cleaning, oxygenation, biofilm thickness control and bulk liquid mixing. Operated under continuous aeration, a bench-scale reactor (70 L) was fed with pre-treated, raw (unsettled) municipal wastewater. BOD(5) and suspended solids removal efficiencies (96 and 99% respectively) were comparable to those obtained with other membrane bioreactors (MBRs). Total nitrogen removal efficiencies of 80% were achieved, which is better than those obtained in other HMBRs and similar to the values reached using more complex MBRs with extra anoxic tanks, intermittent aeration or internal deflectors.     

市政污水生物除磷效能和功能微生物分布特征

调研了4座市政污水处理厂的除磷效能、污泥活性以及微生物分布特征。结果表明出水总磷均达到《城镇污水处理厂污染物排放标准》(GB18918—2002)一级标准,但污泥性能差异显著。活性污泥厌氧释磷率和好氧聚磷率范围分别是0.224～7.77mg/(gVSS.h)和0.386～7.9mg/(gVSS.h)。聚磷假丝酵母菌(Accumulibacter)比例较低,为3.8%～8.7%,聚糖假丝酵母菌(Competibacter)为3.2%～9.1%。进水乙酸含量和乙酸吸收率,厌氧释磷率和好氧聚磷率间都存在很好的线性相关性,表明污水中可利用碳源的数量和磷素的比例极大影响污泥除磷性能。故控制工业废水排入,适当添加碳源,或设置独立的前置反硝化池有望增加污水处理厂的除磷效能。     

对上海城镇污水处理厂污泥处理和处置的几点想法(上)

污泥处理和处置是解决污泥问题密不可分的两个环节,污泥如何处理、达到何种处理程度取决于污泥处置(污泥最终出路)的方式,处置决定处理.结合对上海市城镇污水处理厂污泥处理和处置的想法,阐述了污泥处理和处置的关系.     

Biological wastewater treatment for removal of polymeric resins in UASB reactor: influence of oxygen.

The biological elimination of polymeric resins compounds (PRC) such as acrylic acid and their esters, vinyl acetate and styrene under methanogenic and oxygen-limited methanogenesis conditions was evaluated. Two UASB reactors (A and B) were used and the removal of the organic matter was studied in four stages. Reactor A was used as methanogenic control during the study. Initially both reactors were operated under methanogenic conditions. From the second stage reactor B was fed with 0.6 and 1 mg/L.d of oxygen (O2). Reactor A had diminution in chemical oxygen demand (COD) removal efficiency from 75+/-4% to 37+/-5%, by the increase of PRC loading rate from 750 to 1125 mg COD/L.d. In this reactor there was no styrene elimination. In reactor B the COD removal efficiency was between 73+/-5% and 80+/-2%, even with the addition of O2 and increase of the PRC loading rate, owing to oxygen being used in the partial oxidation of these compounds. In this reactor the yields were modified from 0.56 to 0.40 for CH4 and from 0.31 to 0.60 for CO2. The O2 in low concentrations increased 40.7% the consumption rates of acrylic acid, methyl acrylate and vinyl acetate, allowing styrene consumption with a rate of 0.103 g/L.d. Batch cultures demonstrated that under methanogenic and oxygen-limited methanogenesis conditions, the glucose was not used as an electron acceptor in the elimination of PRC.     

Application of sequencing batch membrane bioreactors (SB-MBR) for the treatment of municipal wastewater

Sequencing batch membrane bioreactors can be a good option in up-grading small municipal plant and for industrial applications, maintaining some of the advantages of both original technologies (effluent quality improvement, flexibility and simplicity of realization, operation and control). In this study, the effects of volumetric exchange ratio (VER) and aeration/filtration strategy have been evaluated. Moreover, with the adoption of cycles shorter than 8 h, the opportunity of further simplification of the membrane operation has been tested by choosing a continuous filtration mode instead of the usual short cycle of permeation/relaxation. Two lab-scales MBR equipped with Zenon hollow fiber modules were fed on real primary effluent. For all tests, hydraulic retention time of 10 h and sludge retention time of 60 days have been adopted. Different cycles have been investigated, lasting between 1 and 8 h and all comprising an anoxic phase to allow for denitrification. Operation at low VER resulted in better effluent quality with no limitations to the denitrification phase. For VER >33% a pre-aeration step was required before effluent withdrawal for optimal ammonium removal. Moreover, VER appeared to have limited negative effect on sludge concentration and yield, while the membrane cleaning frequency slightly increased for increasing VER.     

钢铁厂盐(硫)酸酸洗废液综合治理研究

针对钢铁厂酸洗废液特点,对钢厂盐、硫酸酸洗废液综合治理全盘考虑,提出对盐酸废液采用负压外循环蒸发浓缩结晶法,硫酸废液采用单管填料升膜浓缩结晶法进行综合治理研究,给出了具体工艺流程和经济分析。该研究方法具有蒸发效率高、能连续稳定生产、操作简单、治理过程不需加新酸、设备防腐耐用、操作运转费用低,回收了废酸液中的残余酸和亚铁盐,实现了全厂废酸液的完全零排放。     

MBR technology: a promising approach for the (pre-)treatment of hospital wastewater

Membrane bioreactor (MBR) technology is a very reliable and extensively tested solution for biological wastewater treatment. Nowadays, separate treatment of highly polluted wastewater streams especially from hospitals and other health care facilities is currently under investigation worldwide. In this context, the MBR technology will play a decisive role because an effluent widely cleaned up from solids and nutrients is absolutely mandatory for a subsequent further elimination of organic trace pollutants. Taking hospital wastewater as an example, the aim of this study was to investigate to what extent MBR technology is an adequate 'pre-treatment' solution for further elimination of trace pollutants. Therefore, we investigated - within a 2-year period - the performance of a full-scale hospital wastewater treatment plant (WWTP) equipped with a MBR by referring to conventional chemical and microbiological standard parameters. Furthermore, we measured the energy consumption and tested different operating conditions. According to our findings the MBR treatment of the hospital wastewater was highly efficient in terms of the removal of solids and nutrients. Finally, we did not observe any major adverse effects on the operation and performance of the MBR system which potentially could derive from the composition of the hospital wastewater. In total, the present study proved that MBR technology is a very efficient and reliable treatment approach for the treatment of highly polluted wastewater from hospitals and can be recommended as a suitable pre-treatment solution for further trace pollutant removal.     

Simultaneous domestic wastewater treatment and renewable energy production using microbial fuel cells (MFCs)

Microbial fuel cells (MFCS) can be used in wastewater treatment and to simultaneously produce electricity (renewable energy). MFC technology has already been applied successfully in lab-scale studies to treat domestic wastewater, focussing on organic matter removal and energy production. However, domestic wastewater also contains nitrogen that needs to be treated before being discharged. The goal of this paper is to assess simultaneous domestic wastewater treatment and energy production using an air-cathode MFC, paying special attention to nitrogen compound transformations. An air-cathode MFC was designed and run treating 1.39 L d(-1) of wastewater with an organic load rate of 7.2 kg COD m(-3) d(-1) (80% removal efficiency) and producing 1.42 W m(-3). In terms of nitrogen transformations, the study demonstrates that two different processes took place in the MFC: physical-chemical and biological. Nitrogen loss was observed increasing in line with the power produced. A low level of oxygen was present in the anodic compartment, and ammonium was oxidised to nitrite and nitrate.     

Aerobic granulation in a sequencing batch reactor (SBR) for industrial wastewater treatment.

Aerobic granulation seems to be an a attractive process for COD removal from industrial wastewater, characterised by a high content of soluble organic compounds. In order to evaluate the practical aspects of the process, comparative experimental tests are performed on synthetic and on industrial wastewater, originating from pharmaceutical industry. Two pilot plants are operated as sequencing batch bubble columns. Focus was put on the feasibility of the process for high COD removal and on its operational procedure. For both wastewaters, a rapid formation of aerobic granules is observed along with a high COD removal rate. Granule characteristics are quite similar with respect to the two types of wastewater. It seems that filamentous bacteria are part of the granule structure and that phosphorus precipitation can play an important role in granule formation. For both wastewaters similar removal performances for dissolved biodegradable COD are observed (> 95%). However, a relatively high concentration of suspended solids in the outlet deteriorates the performance with regard to total COD removal. Biomass detachment seems to play a non-negligible role in the current set-up. After a stable operational phase the variation of the pharmaceutical wastewater caused a destabilisation and loss of the granules, despite the control for balanced nutrient supply. The first results with real industrial wastewater demonstrate the feasibility of this innovative process. However, special attention has to be paid to the critical aspects such as granule stability as well as the economic competitiveness, which both will need further investigation and evaluation.     

Biofilm characterization of several wastewater treatment plants with rotating biological contactors in Madrid (Spain)

Ciliate communities were studied in the biofilms of three planes with rotating biological contactors (RBCs) over the period of one year. The aims of this study were: (i) to characterize ciliates to species level; (ii) to determine their abundance and spatial variation through the biological system; and (iii) to relate the spatial segregation and richness of ciliate species to plant performance. A number of species ranging from 33 to 67 were identified at the different plants. The overall best represented groups were peritrichs followed by scuticociliates (Las Matas), cyrtophorids (Boadilla) or hypotrichs (Camarma). Comparison of RBCs and activated sludge communities indicated that even though both were mainly constituted by peritrichs, differences in groups and species composition were observed.     

Biological treatment of toluene contaminated wastewater by Alcaligenese faecalis in an extractive membrane bioreactor; experiments and modeling

Conventional wastewater treatment methods are not efficient in treating wastewaters contaminated with volatile hydrocarbons such as benzene, toluene and xylenes (BTX). The aim of this study is to enhance the efficiency of an extractive membrane bioreactor (EMBR) in treating toluene contaminated wastewater by usage of pure culture of Alcaligenese faecalis. Toluene was used as a model of toxic contaminant because of its wide presence in wastewaters contaminated with petrol derivatives. The Haldane kinetic model adequately described the dynamic behavior of the toluene biodegradation by the strain of A. faecalis over a wide range of initial toluene concentrations (50-1,000 mg L(-1)) with kinetic constants micro(max) = 0.066 h(-1), k(s) = 91.7 mg/L and k(I) = 278.2. Overall mass transfer coefficient has been measured and described as resistance in the series model. No biofilm formed on the exterior surface of the membrane; however in previous works the layer of the biofilm on the exterior surface of the membrane acts as a mass transfer resistance. A mathematical model was developed to predict the pollutant concentration profile along the tube side of the membrane modules.     

BAF工艺处理焦化废水研究

采用单级BAF工艺进行焦化废水处理试验,以水力负荷为控制参数,在正常pH、温度、营养比等条件下,考察BAF对焦化废水的处理效果。结果表明,当水力负荷小于0.2m3/(m2·h)时,BAF能有效地去除焦化废水中的CODCr、酚、氰,去除率均大于90%,其中出水CODCr达到GB13456-92国家二级排放标准,酚、氰低于国家一级排放标准。但其对NH3-N去除效果较差,甚至出水浓度高于进水浓度。此外单级BAF也不能脱去焦化废水的色度,处理后的废水仍为浅酱油色。要使出水达标排放,需采用两段BAF:其中一段为脱碳滤池(除COD),另一段为硝化滤池(脱氮)。