Degradation of wine distillery wastewaters by the combination of aerobic biological treatment with chemical oxidation by Fenton's reagent.

The degradation of wine distillery wastewaters by aerobic biological treatment has been investigated in a batch reactor. The evolution of the chemical oxygen demand, biomass and total contents of polyphenolic and aromatic compounds was followed through each experiment. According to the Contois model, a kinetic expression for the substrate utilization rate is derived, and its biokinetic constant is evaluated. The final effluents of the aerobic biological experiments were oxidized by Fenton's reagent. The evolution of chemical oxygen demand, hydrogen peroxide concentration and total contents of polyphenolic and aromatic compounds was followed through each experiment. A kinetic model to interpret the experimental data is proposed. The kinetic rate constant of the global reaction is determined.     

Degradation of endocrine disrupting chemicals in aqueous solution by interaction of photocatalytic oxidation and ferrate (VI) oxidation.

In this study, the degradation of bisphenol A in aqueous suspension by interaction of photocatalytic oxidation and ferrate(VI) oxidation was investigated under different conditions. The results indicate that the formation of Fe(V) and Fe(IV) is in the photocatalytic reduction of Fe(VI) by electron (ecb-) on the surface of TiO2. The oxidation efficiency of the photocatalytic oxidation in the presence of Fe(VI) was much greater than that without. In addition, the decomposition of Fe(VI) under different conditions was also investigated. The results indicate that the Fe(VI) reduction was accelerated by photocatalytic reaction and the adsorption capacity of Fe(VI) on TiO2 surface decreased as pH increased. The characteristics of solid potassium ferrate prepared were investigated by X-ray diffraction. It was found that the potassium ferrate solid has a tetrahedral structure with a space group of D2h (Pnma) and a = 7.705 A, b = 5.863 A, and c = 10.36 A.     

Gas-phase photocatalytic oxidation of motor fuel oxygenated additives.

Methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) were oxidized in the gas phase by photocatalytic oxidation (PCO). Transient PCO was carried out at room temperature on TiO2 (Degussa P25), 0.2% Pt-TiO2, and 2% Pt-TiO2 catalysts. Surface-adsorbed reaction by-products were characterized by temperature-programmed desorption (TPD) and oxidation (TPO). Continuous flow PCO was also carried out at 373 K on TiO2. Acetone, H2O, and CO2 were the gas-phase products for PCO of TBA and MTBE, and formic acid was adsorbed on the TiO2 surface. Temperature-programmed desorption of TBA and MTBE formed 2-methyl-1-propene, water (TBA), and methanol (MTBE). During continuous-flow PCO, acetone desorbed in molar amounts equal to the amount of decomposed TBA and MTBE. The Pt/TiO2 catalysts had higher rates of complete oxidation during PCO and TPO. Injection of water during transient PCO increased the rates of oxidation of adsorbed TBA, formic acid, and acetone. Photocatalytic oxidation of TBA proceeded faster in humid air than dry air, but MTBE oxidation was less sensitive to humidity. The TiO2 catalyst was stable for MTBE, TBA, and acetone PCO at 373 K. The PCO at low conversions followed the Langmuir-Hinshelwood model.     

Physico-chemical treatment for the depuration of wine distillery wastewaters (vinasses).

In the present work, an integrated Fenton-coagulation/flocculation process was applied for the depuration of wine distillery wastewaters, commonly known as "vinasses". This study evaluates the Fenton process (H2O2/Fe2+), involving oxidation--in a first stage and coagulation/flocculation (using Ca(OH)2 as base-precipitant)--in a second stage for the removal of chemical oxygen demand (COD). The experimental variables studied were the dosages of hydrogen peroxide and iron salts, the molar ratio [H2O2]o: [Fe2+]o, the effluent dilution and the manner in which the reagents were added (splitting the reagent dose of hydrogen peroxide and ferrous salt into different fractions). The optimal operating conditions of the integrated process were: [H2O2]o = 0.5 mol/L using an optimal concentration ratio [H2O2]o: [Fe2+]o= 15 mol/mol. Under these conditions, the COD removal was 74%.     

Electrochemical advanced oxidation process using DiaChem electrodes.

The electrochemical advanced oxidation process (EAOP) using boron doped diamond (DiaChem, registered trademark of Condias GmbH) has been studied for wastewater treatment and drinking water disinfection. DiaChem electrodes consist of preferentially metallic base materials coated with a conductive polycrystalline diamond film by hot-filament chemical vapour deposition. They exhibit high overpotential for water electrolysis as well as high chemical inertness and extended lifetime. In particular the high overpotential for water decomposition opens the widest known electrochemical window, allowing the energy efficient production of hydroxyl radicals directly from aqueous solutions. The hydroxyl radicals on the other hand are effectively used for the oxidation of pollutants. The EAOP using DiaChem electrodes thus facilitates the direct and, if necessary, complete decomposition of even hazardous or persistent pollutants in different wastewaters. Current efficiencies of more than 90%, also without the use of additives for hydroxyl radical generation, have been demonstrated. Additionally, for drinking water preparation diamond electrodes facilitate disinfection with and without the support of chlorine.     

Long term experience with the nutrient limited BAS process for treatment of forest industry wastewaters.

The nutrient limited biofilm-activated sludge (BAS) process was developed with the aim to ensure maximum biological treatment efficiency in combination with good process stability, low sludge production and minimum effluent concentration of nutrients. The first full scale nutrient limited BAS (NLBAS) processes were implemented at S?dra Cell V?r? and Stora Enso Hylte in 2002. Since then another three full scale installations have been built. The aim of this study was to investigate and summarise the long-term treatment results, process stability, sludge production and sludge characteristics for the five full scale NLBAS processes. It was of particular interest to compare the nutrient limited operating mode with regard to the different types of production and wastewater that the mills represent (kraft, TMP and newsprint, bleached CTMP). The study showed that after the initial start-up period, which varied from a couple of weeks to three to four months, all plants meet their respective discharge limits. The sludge production for the different plants varies between 0.07 and 0.15 kg TSS/kg COD and the sludge characteristics are with few exceptions excellent. In conclusion, the nutrient limited BAS process is suitable for both upgrades and new installations of biological treatment for different types of forest industry wastewaters.     

The catalytic and photocatalytic oxidation of organic substances using heterogeneous Fenton-type catalysts.

This paper deals with catalytic and photocatalytic oxidation of organic substances using H202 over heterogeneous Fenton-type catalysts. In the study a series of Fe-containing catalysts was experienced. A zeolite named as FeZSM-5 was selected as the most active heterogeneous Fenton-type catalyst. The FeZSM-5 reported was prepared by hydrothermal crystallization in the presence of iron salt. In contrast to the homogeneous Fenton system the catalyst prepared had minimal, if any, leaching of iron ions, was stable during 30 catalytic runs and didn't lose its activity in the presence of complexing agents, e.g. P2O7(4-). The catalyst was active in oxidation of organic substances at pH from 1.5 to 8, maximum activity was observed at pH = 3. The FeZSM-5 effectively oxidized a simulant of the warfare agent, diethylnitrophenil phosphate, which is hardly detoxified by other methods. It appeared that the rate of oxidation of formic acid, ethanol and benzene over FeZSM-5 increased under the action of visible light (lambda > 436 nm), quantum efficiency being 0.06-0.14.     

UV/H_2O_2降解微囊藻毒素的人工神经网络模型

试验建立了UV/H_2O_2高级氧化工艺降解微囊藻毒素MC-LR的人工神经网络模型.研究了UV强度、H_2O_2投加量、MC-LR初始浓度、pH等对降解速率的影响,并以反向传播算法的神经网络模型对多因素条件下的降解效果进行仿真预测.结果表明,降解速率不受初始MC-LR浓度的影响;UV的加强及H_2O_2投加量的增加能有效提高MC-LR的降解速率;pH的降低能大幅度改善降解效果,尤其在酸性条件下,pH的变化对降解速率的影响程度更大.     

The importance of hydrodynamics in UV advanced oxidation reactors.

The flow field of UV reactors was characterised experimentally using particle image velocimetry (PIV) and modelled with computational fluid dynamics (CFD). The reactor flow was integrated with the radiation fluence rate and photolysis kinetics to calculate the overall conversion of photo-reactant components in annular UV reactors with an inlet parallel and perpendicular to the reactor axis. The results indicated that the fluid flow distribution within the reactor volume affects photo-reactor performance.     

Applications of advanced oxidation processes: present and future.

The use of advanced oxidation processes (AOPs) to remove pollutants in various water treatment applications has been the subject of study for around 30 years. Most of the available processes (Fenton reagent, O3 under basic conditions, O3/H2O2, O3/UV, O3/solid catalyst, H2O2/M(n+), H2O2/UV, photo-assisted Fenton, H2O2/solid catalyst, H2O2/NaClO, TiO2/UV etc.) have been investigated in depth and a considerable body of knowledge has been built up about the reactivity of many pollutants. Various industrial applications have been developed, including ones for ground remediation (TCE, PCE), the removal of pesticides from drinking water, the removal of formaldehyde and phenol from industrial waste water and a reduction in COD from industrial waste water. The development of such AOP applications has been stimulated by increasingly stringent regulations, the pollution of water resources through agricultural and industrial activities and the requirement that industry meet effluent discharge standards. Nevertheless, it is difficult to obtain an accurate picture of the use of AOPs and its exact position in the range of water treatment processes has not been determined to date. The purpose of this overview is to discuss those processes and provide an indication of future trends.     

光催化氧化技术在水处理中的研究进展

介绍了二氧化钛(TiO2)光催化氧化的机理,阐述了TiO2光催化氧化技术在降解水中有机污染物、无机污染物及饮用水净化和垃圾渗滤液处理中的研究进展,并对TiO2光催化氧化技术的研究前景进行了展望.二氧化钛(Ti02)化学性质稳定、难溶、无毒、成本低、催化效率高,因此光催化氧化技术在难降解有机物、微污染水等处理中相对于其他传统水处理工艺具有一定的优势,是一种很有发展前途的水处理技术,对太阳能的利用和环境保护有重要的意义,可以预见光催化氧化将成为新型有效的水处理手段.     

Removal of humic acid foulant from ultrafiltration membrane surface using photocatalytic oxidation process.

The experimental results indicated that without the TiO2 particles and PCO treatment, the permeate flux of ultrafiltration (UF) membrane declined to 40% of the initial permeate flux after 8 hours filtration. Feeding the humic acid solution with TiO2 particles dosage of 1 g/L with calcium ions into UF membrane, after the same filtration time and PCO reaction at 120 minutes, the permeate flux was increased to about 90% of the initial permeate flux. At longer PCO reaction times, a better water quality of UF permeate was observed. It has been found that with the coexistence of calcium ions in humic acid solution, the smaller molecular fragments of humic acid (HA) generated by PCO reaction may be transferred to the surface of TiO2 by means of adsorption. The humic acid adsorption by TiO2 in the presence of Ca2+ is also pH dependent. The adsorption rates were 21.0, 14.9 and 10.8 ppmTOC/gTiO2 for pH value of 4, 7 and 10 respectively. The combination of effects of PCO mineralization of humic acid into CO2 and adsorption of humic acid by TiO2 through the forming of HA-Ca(2+)-TiO2 aggregate particles were responsible for the removal of humic acid foulant from UF membrane surface.     

A multi-site approach towards integrating environmental management in the wine production industry.

Nine wineries and a water bottling plant situated in the Franschhoek Valley, South Africa, have decided to lead the way towards creating a safer and more sustainable environment in the Valley. As part of the Vignerons de Franschhoek ECO Association (VFEA), they adopted a multi-site approach and obtained, in December 2003, the first ISO 14001 multi-site certification in South Africa. This proactive approach allows them better overall environmental performances through mutual motivation, information sharing and comparison of practices by the different participating organisations of Franschhoek Valley. At the initiation of the project, the major concerns were associated with a lack of sound environmental management and training of employees. Of particular concern was also the lack of monitoring and measurement of environmental performance key indicators, especially in water consumption and wastewater disposal areas. Although the system is still in its juvenile stage, it already showed some effluent quality improvements through better wastewater management, better control over chemical stores as well as definite improvement in water management and increase in solid wastes recycling. The latter improvements will definitely entail long-term cost savings should the system be continually and properly maintained. It is the intention of the VFEA to create a more environmentally friendly and sustainable Valley by convincing others to be more environmentally responsive and expanding the ISO 14001 principles to other areas of the organisations including the farms, to other wineries and ultimately to the whole Franschhoek Valley.     

Treatment of an ECF effluent by combined use of activated sludge and advanced oxidation process.

The combined biological and chemical treatments of the cellulose effluents have been studied aiming to promote a more significant degradation of their recalcitrant compounds and to reduce their toxicity, as compared with the isolated treatments. In this work the effluent from acid stages of the ECF bleaching of Eucalyptus urograndis pulp was treated by using separately activated sludge and UV radiation and its combination. The treatment efficiency was evaluated by colour, total phenol, COD, BOD, UV spectroscopy, molar weight distribution and toxicity. The untreated effluent presented 587 +/- 18 CU, 19.3 +/- 0.6 mg.L(-1) of total phenol, 2246 +/- 137 mgO2.L(-1) of COD and 904 +/- 48 mgO2.L(-1) of BOD. It did not show acute toxicity to Escherichia coli, but presented chronic toxicity to Selenastrum capricornutum (EC50 = 25%). The sludge treatment resulted in a colour increasing of 42% and decreasing of total phenol, COD and BOD of 33%, 64% and 92%, respectively. The UV radiation treatment for 120 min resulted in a decrease of colour, total phenol, BOD and COD of 70%, 43%, 62% and 43%, respectively. The combined treatment promoted an expressive decrease for colour and total phenol. The UV absorption indicated a degradation of the aromatic compounds. The biological treatment did not remove chronic toxicity and after UV radiation treatment, a 10 times improving toxicity was noticed.     

Treatments of oil-refinery and steel-mill wastewaters by mesocosm constructed wetland systems.

In this study, two types of industrial wastewater, oil-refining and steel-milling, were selected for investigating their feasibility of treatment by mesocosm constructed wetland systems. The secondly treated effluents from the wastewater treatment plants were directly discharged into the systems controlled at different flow rates. Three wetland mesocosms were installed in the two industries: mesocosms A and B were in the oil refinery, and mesocosm C was in the steel mill. The substratum media used in wetland systems were sand (mesocosm A) and gravel (mesocosms B and C), while the vegetation types selected were reeds (mesocosms A and B) and mixed species of reeds and cattails (mesocosm C). The flow regimes were controlled as free water surface (FWS) and subsurface flow (SSF) for the sand- and gravel-beds, respectively. According to the experimental results, we found that the system treating oil-refining wastewater performed better than that treating steel-milling wastewater learned by comparing the removal efficiencies of COD, total N and total P. In addition, it was found that for oil-refining wastewater treatments, the SSF wetland system (mesocosm B) performed better than FWS (mesocosm A) wetland system when comparing both of their removal of pollutants and growth of vegetation. Besides, the effluents from these two industrial wetland treatment systems might be reclaimed and reused for boiler water, cooling, cleaning and miscellaneous purposes in industries. Further treatments are required if the constructed wetland effluents are thought about being reused for processing in industries.     

UASB-接触氧化工艺处理黄酒废水工程实例

结合工程实例,介绍了UASB-接触氧化工艺处理黄酒废水的主要工艺设计参数,调试运行过程;分析了调试运行过程中出现各种现象的原因;总结了设计运行过程中的经验和教训.     

The effect of the textile industry dye bath additive EDTMPA on colour removal characteristics by ozone oxidation.

In this study, the effects of the phosphonic acid based sequestering agent EDTMPA used in the textile dye baths on colour and organic matter removal by ozone oxidation was experimentally investigated. Procion Navy HEXL dyestuff that has been commonly used for the reactive dyeing of cellulose fibers was selected as the model component. The organic matter oxidation by ozone was determined to obey the pseudo-first order kinetics as they are treated singly or in combination. COD removal rates obtained from pseudo-first order reaction kinetics showed that oxidation of Navy HEXL alone (0.0947 L/min) was faster than that of EDTMPA (0.0171 L/min) and EDTMPA with dye (0.0155 L/min) at pH 3.0. It was also found that reaction rates of single EDTMPA removal and EDTMPA and dye mixture removal increased as the reaction pH was increased from 3.0 to 10.5.     

Effect of advanced oxidation processes on the toxicity of municipal landfill leachates.

The aim of the present study was to assess the effect of advanced oxidation processes (AOPs) (oxidation ozone and peroxide/ozone) on the toxicity of leachates from municipal landfill for Warsaw, Poland, using a battery of tests. AOPs used to pre-treat leachates were carried out in laboratory conditions after their coagulation with the use of FeCl3. The effects of the pre-treatment of leachates using the method of coagulation with FeCl3 depended on the concentration of organic compounds and with optimal conditions of the process ranged from 40 to 70%. Further pre-treatment of the leachates after coagulation, involving the use of oxidation with 03 and H2O2/O3, did not cause significant decrease of leachate toxicity. The data of this study demonstrated the usefulness of the battery of tests using Daphnia magna, Artemia franciscana, Scenedesmus quadricauda and Vibrio fischeri for the toxicity evaluation of raw and pre-treated leachates.     

臭氧及其高级氧化工艺对消毒副产物的控制研究

饮用水处理中产生的消毒副产物(DBPs)具有致癌致突变等健康风险,且其在水中广泛存在,引起了水处理行业的广泛关注。DBPs的前体物主要是消毒前未被水处理工艺去除,且能与消毒剂反应形成DBPs的有机物或无机离子。在消毒前,通过增设新的处理工艺(如预处理或深度处理工艺)以去除DBPs前体物,是控制DBPs的有效措施。臭氧及其高级氧化工艺能够有效氧化降解部分有机污染物,所以其已经成为控制某些典型DBPs的重要工艺。综述了臭氧及其高级氧化技术对典型DBPs——三卤甲烷及卤乙酸的控制效果,详细讨论了这些技术的降解效率、机理及反应动力学,以期为微污染原水条件下DBPs的有效控制提供有益参考。     

Acidogenic pretreatment of wastewaters containing 2-nitrophenol.

Anaerobic Toxicity Assay (ATA) tests were conducted on acidogenic cultures to assess the feasibility of using acidogenic processes to treat wastewaters containing 2-nitrophenol. Results indicated 2-nitrophenol could be removed with a removal efficiency of more than 98%. 2-aminophenol was identified as the major metabolite of the biotransformation of 2-nitrophenol. Reduction in inhibition potential of acidogenic pretreated effluent was observed in the aerobic process. EC50 values of 2-nitrophenol and 2-aminophenol were found to be 0.065 mM and 1.83 mM respectively.