Continuous flow removal of acid fuchsine by dielectric barrier discharge plasma water bed enhanced by activated carbon adsorption

Continuous processes which allow for large amount of wastewater to be treated to meet drainage standards while reducing treatment time and energy consumption are urgently needed. In this study, a dielectric barrier discharge plasma water bed system was designed and then coupled with granular activated carbon (GAC) adsorption to rapidly remove acid fuchsine (AF) with high efficiency. Effects of feeding gases, treatment time and initial concentration of AF on removal efficiency were investigated. Results showed that compared to the N2 and air plasmas treatments, O2 plasma processing was most effective for AF degradation due to the strong oxidation ability of generated activated species, especially the OH radicals. The addition of GAC significantly enhanced the removal efficiency of AF in aqueous solution and shorten the required time by 50%. The effect was attributed to the ability of porous carbon to trap and concentrate the dye, increasing the time dye molecules were exposed to the plasma discharge zone, and to enhance the production of OH radicals on/in GAC to boost the degradation of dyes by plasma as well as in situ regenerate the exhausted GAC. The study offers a new opportunity for continuous effective remediation of wastewater contaminated with organic dyes using plasma technologies.     

The Use of Ultrasonics in the Treatment of Waste Activated Sludge

1 INTRODUCTION Waste activated sludge (WAS) processes are key technologies to treat wastewater. Through their micro-bial activity, these biological processes produce how-ever huge amounts of WAS as an inevitable drawback of the WAS-process. Various techniques have been studied to further reduce the amount of excess sludge through (1) the maximum use of biological phospho-rus removal instead of chemical precipitation[1,2]; (2) the use of advanced treatment techniques such as per-oxidati…     

Photodegradation of benzothiazole ionic liquids catalyzed by titanium dioxide and silver-loaded titanium dioxide

In recent years, ionic liquids(ILs) have been widely used in extraction, synthesis, electrochemistry and other fields.Meanwhile, the environmental impact of ILs has been attracting a lot of attention, and eco-friendly treatment for ILs is becoming a necessary subject. In this study, photocatalytic degradations of benzothiazole ILs catalyzed by titanium dioxide(TiO_2) and silver-loaded titanium dioxide(Ag/TiO_2) were studied for the first time. The degradation of benzothiazole hexafluorophosphate([C4 Bth]PF6) could reach more than 99% within 240 min with the catalysis of TiO_2. To improve catalytic efficiency, Ag/TiO_2 was synthesized and characterized by UV–Vis diffuse reflectance absorption spectra(DRS) and X-ray photoelectron spectroscopy(XPS). The degradation of [C4 Bth]PF6 could reach more than 99% within 120 min in the degradation catalyzed by Ag/TiO_2. The photodegradation products of benzothiazole ILs are composed of inorganic substances or organic substances with simpler structures, which are easier to decompose and less toxic. The degradation system proposed by this study could provide a simple, green,safe, and economical method for the efficient treatment of benzothiazole ILs.     

含酚废水处理的吸附和臭氧氧化动力学模型

A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continuously fed co-currently as upward flow into the reactor at constant flow rate of 2 and 1 L·min1,respectively.The phenolic treatment results in seven cases were compared:(a)O3 only,(b)fresh granular activated carbon(GAC),(c) 1st reused GAC,(d)2nd reused GAC,(e)fresh GAC enhanced with O3,(f)1st reused GAC enhanced with O3,and (g)2nd reused GAC enhanced with O3.The phenolic wastewater was re-circulated through the reactor and its concentration was measured with respect to time.The experimental results revealed that the phenolic degradation using GAC enhanced with O3 provided the best result.The effect of adsorption by activated carbon was stronger than the effect of oxidation by ozone.Fresh GAC could adsorb phenol better than reused GAC.All cases of adsorption on GAC followed the Langmuir isotherm and displayed pseudo second order adsorption kinetics.Finally,a differential equation for the fluidized bed reactor model was used to describe the phenol concentration with respect to time for GAC enhanced with O3.The calculated results agree reasonably well with the experimental results.     

Degradation analysis of A2/O combined with AgNO3+K2FeO4 on coking wastewater

In this work, a coking wastewater was selected and a biochemical A~2/O treatment device for fractional degradation was designed and employed. After each stage of the treatment, the products were analyzed through gas chromatography–mass spectroscopy(GC–MS) to determine their composition. Finally, AgNO_3+ K_2 FeO_4 was used as an advanced deep catalytic oxidation treatment. It was concluded from the analysis that cyclic organics could be degraded and the chemical oxygen demand(COD) was controlled within 50 mg·L~(-1), in line with the target value. Meanwhile, the spectra obtained from the GC–MS were in accordance with the conclusions reached based on the COD. The research results showed that all hard-degradable organics in coking wastewater could be eliminated through the A~2/O bio-membrane treatment and the advanced treatment of making use of K_2FeO_4 as an oxidant and Ag+as a catalyst, the catalytic efficiency with Ag+as a catalyst of K+2FeO_4 was very high. Agcould evidently improve the oxidation capacity of K_2FeO_4 to wastewater in its short stability time, and this is an important innovation.     

Computational design of heterogeneous catalysts and gas separation materials for advanced chemical processing

Functional materials are widely used in chemical industry in order to reduce the process cost while simultaneously increase the product quality.Considering their significant effects,systematic methods for the optimal selection and design of materials are essential.The conventional synthesis-and-test method for materials development is inefficient and costly.Additionally,the performance of the resulting materials is usually limited by the designer’s expertise.During the past few decades,computational methods have been significantly developed and they now become a very important tool for the optimal design of functional materials for various chemical processes.This article selectively focuses on two important process functional materials,namely heterogeneous catalyst and gas separation agent.Theoretical methods and representative works for computational screening and design of these materials are reviewed.     

An overview of carbon nanotubes role in heavy metals removal from wastewater

The scarcity of water, mainly in arid and semiarid areas of the world is exerting exceptional pressure on sources and necessitates offering satisfactory water for human and different uses. Water recycle/reuse has confirmed to be successful and promising in reliable water delivery. For that reason, attention is being paid to the effective treatment of alternative resources of water (other than fresh water) which includes seawater, storm water, wastewater (e.g., dealt with sewage water), and industrial wastewater. Carbon nanotubes (CNTs) are called the technology of 21st century. Nowadays CNTs have been widely used for adsorption of heavy metals from water/ wastewater due to their unique physical and chemical properties. This paper reviews some recent progress (from 2013 to 2018) in the application of CNTs for the adsorption of heavy metals in order to remove toxic pollutants from contaminated water. CNTs are expected to be a promising adsorbent in the future because of its high adsorption potential in comparison to many traditional adsorbents.     

超声气升式反应器处理乐果水溶液

Ultrasonic airlift loop reactor （UALR） shows potential and wide application for wastewater treatment. In this paper the performance and efficiency of UALR in dimethoate degradation were presented. The effects of O3 flow rate, ultrasonic intensity and initial concentration of dimethoate on degradation rate were investigated. UALR imposed a synergistic effect combining sonochemical merit with high O3 transfer rate. The results showed that UALR not only increased degradation rate, but also was better than the simole sum of degradation by O3 and ultrasound separately. Under the operation conditions of O3 flow of 0.34 m^3·h^-1, ultrasonic intensity 3.71 W.cm^-2, and initial concentration of dimethoate at 20 mg·L^- 1, the degradation rate of dimethoate increased to 80%. UALR seems an advisable choice for treating organic wastewater and this process may have wide application prospect in industry.     

Non-linear modeling of kinetic and equilibrium data for the adsorption of hexavalent chromium by carbon nanomaterials:Dimension and functionalization

The adsorption capacities for the removal of hexavalent chromium from aqueous solutions by six carbon nanomaterials have been evaluated. Single-walled and multi-walled carbon nanotubes as received and after oxidation treatment, graphene oxide and reduced graphene oxide are the materials with different dimension and functionalization compared in this research. Carbon nanotubes have been modified using hydrogen peroxide as oxidizing agent under microwave radiation. The oxidation treatment on carbon nanotubes has a positive effect increasing the adsorbent–adsorbate interaction. Rate-controlling mechanisms and equilibrium data are analyzed using non-linear models. Non-linear method is proposed as the most suitable method for determining the kinetic and equilibrium parameters. The values of adsorption energy(E) obtained from the Dubinin–Radushkevich isotherm,have been found around 0.371 and 0.870 k J·mol~(-1), indicating physical adsorption. Therefore, the pseudo-second order model represents better the kinetic experimental data. The results show that the Langmuir isotherm provides a slightly better fit to the experimental data compared with the Freundlich isotherm, indicating homogeneous distribution of active sites on carbon nanomaterials and monolayer adsorption. The separation factors RLare found in the range of 0–1, suggesting that the adsorption process is suitable for all adsorbents. The mechanisms for hexavalent chromium removal have been proposed as electrostatic interactions and hydrogen bonding.     

Separation of light hydrocarbons with ionic liquids: A review

Light hydrocarbons(C_1–C_4) are fundamental raw materials in the petroleum and chemical industry. Separation and purification of structurally similar paraffin/olefin/alkyne mixtures are important for the production of highpurity or even polymer-grade light hydrocarbons. However, traditional methods such as cryogenic distillation and solvent absorption are energy-intensive and environmentally unfriendly processes. Ionic liquids(ILs) as a new alternative to organic solvents have been proposed as promising green media for light hydrocarbon separation due to their unique tunable structures and physicochemical properties resulting from the variations of the cations and anions such as low volatility, high thermal stability, large liquidus range, good miscibility with light hydrocarbons, excellent molecular recognition ability and adjustable hydrophylicity/hydrophobicity. In this review, the recent progresses on the light hydrocarbon separation using ILs are summarized, and some parameters of ILs that influence the separation performance are discussed.     

化学合成制药废水处理工程

化学合成制药废水生物毒性大、可生化性差,属高难度难降解的有机废水,结合本公司工程中的实际应用,高浓度废水采用两级高级氧化工艺为：微电解＋芬顿氧化＋电催化氧化的方法处理,效果很好,COD和ss的去除率分别可达93．8％和90％~A．-k-,各项指标均达到企业所在园区污水处理厂接管标准,为难降解有机废水的处理提供了新的处理途径。     

Ozonation and Advanced Oxidation Treatment of Emerging Organic Pollutants in Water and Wastewater

A vast number of persistent organic pollutants have been found in wastewater effluent, surface water, and drinking water around the world. This indicates their ineffective removal from water and wastewater using conventional treatment technologies. In addition to classical persistent organics such as organochlorine insecticides, solvents, and polychlorinated biphenyls, a growing number of emerging pollutants of both synthetic and natural origins have been identified as major environmental pollutants in recent years. A variety of advanced and conventional treatment options have been suggested for the removal and/or destruction of these persistent organics in water and wastewater, such as chemical oxidation, activated carbon adsorption, and membrane filtration. Of these options, chemical oxidation using ozone, alone or in combination with additional physical/chemical agents (i.e., advanced oxidation), has been proved a highly effective treatment process for a wide spectrum of emerging aqueous organic pollutants, including pesticides, pharmaceuticals, personal care products, surfactants, microbial toxins, and natural fatty acids. In this paper, we discuss the emerging organic pollutants of concern in the aquatic environment and focus on the issues associated with their removal using ozonation and advanced oxidation processes.     

超声协同其它技术处理含酚废水

超声降解法水处理技术是一种很有发展前途的新兴有机废水处理技术。介绍了超声波技术处理难降解含酚废水的工作原理,以及近几年来超声协同其它技术物理方法(活性炭吸附法、液膜法)、化学方法(电化学法、光化学方法、深度氧化法)以及生物方法(活性污泥法、酶处理法)降解含酚废水的最新研究成果与结论,对其中存在的一些问题进行了讨论,并指出今后的重点研究方向。     

Atrazine Removal in Municipal Secondary Effluents by Fenton and Photo‐Fenton Treatments

Alternative water sources, including effluents from municipal wastewater treatment plants (MWTP) are necessary to meet increasing water demand. Advanced oxidation processes based on the Fenton reaction were applied to remove atrazine from the secondary effluents of a MWTP that uses activated sludge. Fenton, UV‐A photo‐Fenton, and UV‐C photo‐Fenton treatments were tested. Atrazine removal percentages were around 20 % for Fenton, 60 % for UV‐A photo‐Fenton and 70 % for UV‐C photo‐Fenton treatments, respectively. Organic matter mineralization by Fenton treatment was monitored and no significant reduction was observed. However, organic matter oxidation in terms of COD reduction of around 30 and 40 % were achieved by Fenton and photo‐Fenton processes, respectively. The photo‐Fenton process with UV‐C is a useful technique for atrazine degradation, leading to higher degradation than with UV‐A while also being more attractive in an economic point of view.     

H2O2强化光催化处理苯胺化工废水的应用试验

研究者在苯胺模拟废水高级氧化处理方面开展了很多研究，但针对炼化企业苯胺装置废水含盐高、色度高、COD降解难等问题尚未开展工程应用。为解决苯胺生产废水的实际问题，本研究开展了TiO₂/UV-H₂O₂氧化降解苯胺废水（1~2m³/h）的现场试验研究。考察了苯胺废水在单独TiO₂/UV、单独H₂O₂氧化及TiO₂/UV-H₂O₂协同作用下的处理效果，提出了苯胺废水的最佳处理工艺方案，并进行了成本核算。结果表明，单独TiO₂/UV和单独H₂O₂氧化对苯胺废水的脱色率和COD去除率偏低，而TiO₂/UV-H₂O₂协同作用时苯胺废水脱色率和COD去除率可达95%以上。协同氧化体系中，H₂O₂的氧化降解作用显著，H₂O₂投加量1%~2%；酸性条件利于苯胺废水的降解，特别是pH=3.8~4.2时；TiO₂/UV和H₂O₂协同作用一段时间后，停止UV而凭借残余H₂O₂可以将体系中的中间产物继续降解直至矿化成CO₂。TiO₂/UV- H₂O₂协同处理炼化企业苯胺生产废水，出水COD≤60mg/L，色度≤20倍，单位能耗约18.44kW·h/m³，明显低于文献报道值，具有显著的技术性与经济性。     

电催化氧化技术降解有机废水的研究进展

水体中存在的微量持久性有机污染物对人类及生物的正常生命活动构成了严重威胁,有效去除这些污染物已成为当务之急。电催化氧化技术因具有适应性广,氧化性强,无二次污染,反应迅速,设备及其操作简单等优点而日益成为难降解有机废水处理领域的研究热点。论文论述了目前国内外有关电催化氧化处理有机废水的基本原理及应用现状,并讨论了该领域研究中存在的问题和发展方向。     

低温等离子体技术处理难降解有机废水的研究进展

高压放电能够产生低温等离子体,可引起多种物理和化学效应。该技术处理废水具有高能电子、紫外光、O₃等多因素的综合作用,是集光、电、化学等多种氧化于一体的新型水处理技术,具有良好的发展前景。本文介绍了低温等离子体技术处理难降解有机废水的作用过程及其机理,综述了脉冲电晕放电、介质阻挡放电、辉光放电和滑动弧放电等离子体处理有机废水的国内外研究现状和发展趋势,探讨了这些技术在废水处理中目前存在的处理对象单一、处理工艺成本高等主要问题,并指出今后要重点优化处理工艺,降低处理成本和能耗,着眼于产业应用,使这项新兴技术尽早应用到实际的工业废水处理中。     

The Effectiveness in the Removal of PAHs from Aqueous Solutions in Physical and Chemical Processes: A Review

Polycyclic aromatic hydrocarbons (PAHs) are relatively well-known organic pollutants and due to their carcinogenic and mutagenic properties, their presence in the aqueous environment still attracts a lot of attention. This article presents a critical review of the literature on the application of physical and chemical processes for removal of PAHs from aqueous solution, including water and wastewater. The effectiveness of coagulation, chemical oxidation, photodegradation, sorption, and membrane processes in the degradation or removal of these micropollutants is described. The PAHs removal efficiency (coagulation ～ 99%, chemical oxidation ～ 87%, photodegradation ～ 93%, sorption ～ 100%, and membrane ～ 100%) during the above processes is difficult to compare due to the works conducted under different conditions and using various mediums, e.g., water, wastewater, PAHs model aqueous solutions.     

一种环境友好型处理染料废水方法——超声催化二氧化钛深度处理法

超声技术作为一种新型的氧化方法，能提高难降解有机物的降解率和增强水处理中的生物活性，在废水处理中已经发挥了一定的作用并具有广阔的发展前景。光催化氧化降解水体中有机污染物也是近年来兴起的一项急剧发展前景的新型水处理技术，能有效降解废水中的难降解有机物。但因其对光源要求较高等原因限制了它的使用。文章介绍了用超声代替紫外光源降解印染业污水的方法，探讨了降解机理，综述了其在废水处理中的研究进展，并指出今后须解决的问题和发展方向。