Applications of high-gravity technologies in gas purifications: A review

The traditional gas purification techniques such as wet gas desulfurization, with their advantages of large-scale implementation and maturity, have still been widely used. However, the main drawback of these techniques is the low transfer efficiency, which normally needs towers as tall as tens of meters to remove the pollutants. Therefore, new technologies which could enhance the mass transfer efficiency and are less energy-intensive are highly desirable. As a process intensification technology, high-gravity technology, which is carried out in a rotating packed bed(RPB), has recently demonstrated great potential for industrial applications due to its high mass transfer efficiency, energy-saving, and smaller volume. This consequently provides higher efficiency in toxic gas removal, and can significantly reduce the investment and operation costs. In this review, the mechanism,characteristics, recent developments, and the industry applications of high-gravity technologies in gas purifications, such as hydrogen sulfide, nitrogen oxide, carbon dioxide, sulfur dioxide, volatile organic compounds and nanoparticle removal are discussed, most of the demonstration projects and practical application examples in gas purification come from China. The perspective and prospective of this technology in gas purification and other fields are also briefly discussed.     

Hydrogen production with carbon nanotubes based cathode catalysts in microbial electrolysis cells

BACKGROUND: Microbial electrolysis cell (MEC) has been considered as a promising new technology for the production of bio‐hydrogen from renewable biomass, but low‐cost alternatives to typical cathode material (platinum) are needed. In this study, CNTs‐based electrode alternatives to Pt were examined in a single‐chamber membrane‐free MEC. To the best of our knowledge, the use of carbon nanotube as the MEC cathode catalyst has not been reported so far. RESULTS: For all cathodes, hydrogen production rates increased in response to increase in voltage and the highest hydrogen production was achieved at 0.9 V. At an applied voltage of 0.9 V, MECs with Pt/MWNT cathodes obtained a hydrogen production rate of 1.42 m³ m^?3 day^?1 with a current density of 192 A m^?3, a coulombic efficiency of 94%, a cathodic hydrogen recovery of 65%, and electrical energy efficiency based on electricity input of 126%. CONCLUSIONS: The Pt/MWNT cathode developed demonstrated better electrocatalytic activity than the MWNT cathode and achieved performance comparable with the Pt cathode in terms of hydrogen production rate. These results demonstrate the great potential of using carbon cloth with CNTs‐based electrodes as a cathode material for MECs. Copyright © 2012 Society of Chemical Industry     

微生物电解池产甲烷技术研究进展

微生物电解池（microbial electrolysis cell,MEC）产甲烷技术是以微生物为催化剂,利用外界输入的电能将CO₂或有机污染物转化为甲烷的新技术。MEC在实现CO₂处置与能量转化的同时,能够处理污水、污泥、沼渣等多种污染物并生产甲烷,具有能量转化率高、生产成本低、环境友好等特点,可望成为解决能源紧缺和环境破坏问题的重要途径之一。近年来,MEC在产甲烷生物阴极结构及电子传递途径、产甲烷微生物群落等方面得到了广泛关注,同时,MEC耦合厌氧消化或其他废水处理系统形成的产甲烷新技术也逐渐研发并成为研究热点。本文综述了产甲烷生物阴极、产甲烷微生物群落等方面的研究现状,介绍了MEC耦合厌氧消化或其他系统产甲烷新技术,总结并分析了MEC产甲烷技术的研究方向和实用化过程仍需解决的技术难题。     

Emerging technologies for selenium separation and recovery from aqueous systems: A review for sustainable management strategy

Selenium (Se) is known both as an essential micronutrient for human health as well as a toxic element when consumed in excess. This work endeavours to critically review the existing selenium literature over the period 1980–2021, following a systematic sub-classification into the domains of occurrence, speciation, and existing conventional and advanced technologies, while directing further research towards emerging integrated sustainable recovery strategies. The review reveals that the majority of the conventional and advanced separation techniques eventually lead to secondary pollution rather than offering a complete solution, whereas resource recovery studies from water are very scant. Some of the techniques, being miserably slow, cannot be applied in the situations of the occurrence of excess selenium in drinking water, posing a serious threat to human health. Research efforts have so far been directed mainly at the removal of selenium rather than recovery through processes that have the potential of turning selenium abatement technology into a sustainable one with value addition. Emerging integrated technologies involving resource recovery from waste streams or generated sludge such as physicochemical technologies, biochemical reduction, electro-biological reduction, and membrane-based hybrid technologies are presently at a very early development stage. Moreover, the application of studies where Se nanoparticles (SeNPs) ormetal selenides are obtained is very limited, which may be attributed to the particle size, purity, morphology, and challenges involved in their separation. This review evaluates the challenges in separation and resource recovery from contaminated streams and points future research in a new direction.     

Nanoscale zinc oxide based heterojunctions as visible light active photocatalysts for hydrogen energy and environmental remediation

ABSTRACT

In the recent years, zinc oxide has emerged as one of the promising alternate materials to titania for photocatalytic applications due to its several advantages properties. This review recapitulates the ongoing advancement in the field of ZnO-based heterojunctions as visible light responsive photocatalysts for energy conversion (hydrogen evolution) and environmental remediation (pollutants degradation) applications. After a short introduction about zinc oxide materials, the various approaches utilized in the design and development of efficient ZnO-based nanoheterostructures has been discussed in detail. Specifically, strategies such as coupling ZnO with other semiconductors, supporting on carbonaceous materials, decorating with noble metal nanoparticles, doping with heteroatoms and engineering defects in the semiconductor material have been elaborated with a particular emphasis on hydrogen energy and organic pollutants removal. Finally, the future perspective of this material has been highlighted. This comprehensive review not only summarizes the recent literature in this topic, but also provides a detailed insight on the scope of this material for hydrogen energy and environmental remediation applications.     

邻苯二甲酸酯在水环境中的分布及去除技术研究进展

邻苯二甲酸酯(PAEs)是我国地表水和污水处理厂中高频检出的一类微量难降解有机污染物,在水环境中的浓度一般是μg/L级别,但对人体具有内分泌干扰毒性和生殖毒性,是关系到二级生化出水深度处理和再生水安全利用的重要污染物.文中系统综述了PAEs的理化性质、环境风险和在水环境中的分布特征,总结了国内外污水处理厂中PAEs的处...     

机械化学方法在环境污染控制领域的应用研究进展

机械化学方法发展迅速,应用广泛,是环境污染治理领域的重要技术之一,其在持久性有机污染物（POPs）降解方面展现出良好的前景。与其他处理方法相比,机械化学方法反应彻底、溶剂需求量少、反应条件简单、处理成本低且几乎不产生二次污染等优势吸引了越来越多研究人员的关注。本文介绍了机械化学的起源以及机械化学作用于物料过程的等离子模型以及表面化学断键产生自由电子、晶体缺陷促进反应等作用机制,综述了机械化学方法在环境污染控制领域如污染物降解与处置以及废弃物回收等方面的成果,重点从主添加剂类别、氯代持久性有机污染物和其他持久性有机污染物方面阐述了机械化学方法在POPs治理方面的研究现状,总结了POPs在机械化学作用过程的反应机理,指出了目前研究工作的不足,为推广机械化学处理POPs及其污染土壤指明了研究方向。     

Electrically accelerated removal of organic pollutants by a three‐dimensional graphene aerogel

Fast and effective methods for the removal of pollutants are crucial for the development of new sustainable water treatment technologies. In this work, we have reported the electrically accelerated removal of some typical organic pollutants by a three‐dimensional graphene aerogel (3DG). The porous 3DG was fabricated by chemical reduction of graphene oxide. The morphology and structure of 3DG were characterized by microscopic and spectroscopic approaches. The experiments indicated that 3DG‐based electrosorption could accelerate the removal of positively and negatively charged pollutants, such as Acid Red 88, Orange II, and Methylene Blue, as well as enhance the maximum adsorption capacity toward these contaminants. The interaction mechanisms between these organic pollutants and 3DG surface were further elucidated by Dispersion corrected Density Functional Theory (DFT‐D) calculations. This 3DG‐based system offers a potentially effective method for the rapid removal of organic pollutants and provides a new sustainable approach for water and wastewater treatment. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2154–2162, 2016     

Treatment of perchlorate in drinking water: A critical review

Because of its extremely low concentrations and strong resistance to most treatment technologies, perchlorate has become one of the biggest challenges currently being faced by the drinking water industry. Although significant research has been performed to evaluate different treatment technologies for perchlorate removal from drinking water, there has not been a holistic review performed recently. A complete and critical review on the intriguing contaminant ‘perchlorate’ is presented. The sources of perchlorate along with the degree of contamination are discussed. The policy aspects including the regulation and toxicity in addition to the most recent developments in perchlorate analysis are also considered. The applicable treatment technologies including their feasibility are discussed in detail. Although some technologies such as microbial reduction and ion-exchange have become more established than the others, there is still not a single technology that can be directly applied to a drinking water treatment system for compete removal of perchlorate. Although significant research is still being conducted to come up with a novel technology for perchlorate remediation, it is highly likely that it would not be a single novice or conventional technology but a combination of these technologies that would have to be employed to overcome this challenge.     

Recent advances in nanostructured Sn−Ln mixed-metal oxides as sunlight-activated nanophotocatalyst for high-efficient removal of environmental pollutants

Environmental contaminants are toxic and undesirable compounds that can endanger the health and survivorship of human society. Thus, their removal from the environment has become a hot subject of research. Photocatalysis is accepted as a beneficial and environmentally friendly solution for the removal of undesirable contaminants. Its most substantial advantage is the capability to mineralize a wide variety of contaminants. Among various nanoscale compounds, mixed-metal oxides of tin (Sn) and lanthanide (Ln) with unique features and high reactivity have been demonstrated to be promising photocatalysts for removing undesirable contaminants. This review is aimed to give a comprehensive overview of current research progress concerning solar photocatalytic applications utilizing mixed-metal oxides of tin (Sn) and lanthanide (Ln). Diverse techniques for fabrication of mixed-metal oxides of tin (Sn) and lanthanide (Ln) and comprehensive experimental outcomes revealing their application in solar photocatalysis for removing undesirable pollutants are summarized. Besides, factors influencing the solar photocatalytic process have been briefly discussed. Ultimately, inspiring outlooks on this area of research are offered with the purpose of prevailing challenges.     

Abatement of Organic Pollutant Concentrations in Residual Treatment Sludges: A Review of Selected Treatment Technologies Including Drying

As a result of increasing population, industrialization, and effluent quality, sludge production has increased worldwide. Organic micropollutants in sludge have become a more critical environmental health concern compared to heavy metals. New sludge disposal regulations limit persistent organic pollutants (POPs) in addition to conventional organic indicators like total and dissolved organic carbon. This study aims at providing a brief review on POP concentration in the sludge in different regions of the world, sludge regulations, assessment of conventional biological sludge stabilization methods according to their ability to remove POPs, and discussions on alternative sludge treatment methods. The impact of sludge treatment unit operations including conditioning, thickening, mechanical and thermal dewatering, and biological and thermal stabilization on sludge management is also discussed in the context of organics. The occurrence and removal of micropollutants such as absorbable organic halogen compounds (AOX), nonylphenol and nonylphenol ethoxylates (NPE), di-2-(ethyl-hexyl)-phthalate (DEHP), dibenzo-p-dioxins and furans (PCDD/F), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) are also evaluated specifically for sludge treatment unit operations. A concise discussion is also included on different drying technologies suitable for drying of sludge.     

An overview of heavy metal removal from wastewater using magnetotactic bacteria

Considering the increase in water contamination by heavy metal discharge, water quality experts are focusing on innovative future technologies for wastewater treatment. There are a number of physical, chemical and biological processes for acquiring high‐quality effluents; however, these treatment technologies have shown some limitations regarding their specific pollutant removal efficiencies, vulnerability to environmental pollutants, higher cost and energy requirements, excessive sludge volume and toxicity issues. Therefore, this review/concept paper focuses on the application of magnetotactic bacteria (MTB) in the removal of heavy metal from wastewater and also proposes a model application of MTB‐based treatment process. The unique property of the MTB is to move along the periphery of the applied external magnetic fields due to nano sized magnetosomes (MS). MS are basically the biomineral crystals of either magnetite (Fe₃O₄) or greigite (Fe₃S₄) with a size range of 30–120 nm. Moreover, challenging aspects concerning MTB employment in the removal of heavy metal from wastewater also are discussed in detail for the consideration of experts who are involved in the development of new treatment technologies or for retrofications of existing processes. © 2018 Society of Chemical Industry     

发酵制氢废液的微生物电解池产氢

采用单室微生物电解池（MEC）反应器为实验装置,通过预处理技术强化发酵制氢废液中乙酸的积累,并将该发酵废液作为底物,考察了以废液中累积的乙酸作为主要电子供体、碳布为阳极、涂布有Ni纳米颗粒的不锈钢网为催化阴极的产氢效果。结果表明,在MEC中,以预处理的发酵制氢废液积累的乙酸为底物,最高产氢率可达(1.31±0.04) m3H2/(m3?d)和(2.78±0.11) mLH2/mgCOD,同时可获得138.6%±3.1%的能量效率和99.0%±0.3%的COD去除率。实验表明,利用MEC可将发酵末端产物进一步降解,从而减弱了“发酵障碍”现象,实现了治污和产能的统一。     

Membrane bioreactors for hospital wastewater treatment: recent advancements in membranes and processes

Discharged hospital wastewater contains various pathogenic microorganisms, antibiotic groups, toxic organic compounds, radioactive elements, and ionic pollutants. These contaminants harm the environment and human health causing the spread of disease. Thus, effective treatment of hospital wastewater is an urgent task for sustainable development. Membranes, with controllable porous and nonporous structures, have been rapidly developed for molecular separations. In particular, membrane bioreactor (MBR) technology demonstrated high removal efficiency toward organic compounds and low waste sludge production. To further enhance the separation efficiency and achieve material recovery from hospital waste streams, novel concepts of MBRs and their applications are rapidly evolved through hybridizing novel membranes (non hydrophilic ultrafiltration/microfiltration) into the MBR units (hybrid MBRs) or the MBR as a pretreatment step and integrating other membrane processes as subsequent secondary purification step (integrated MBR-membrane systems). However, there is a lack of reviews on the latest advancement in MBR technologies for hospital wastewater treatment, and analysis on its major challenges and future trends. This review started with an overview of main pollutants in common hospital wastewater, followed by an understanding on the key performance indicators/criteria in MBR membranes (i.e., solute selectivity) and processes (e.g., fouling). Then, an in-depth analysis was provided into the recent development of hybrid MBR and integrated MBR-membrane system concepts, and applications correlated with wastewater sources, with a particular focus on hospital wastewaters. It is anticipated that this review will shed light on the knowledge gaps in the field, highlighting the potential contribution of hybrid MBRs and integrated MBR-membrane systems toward global epidemic prevention.     

Recent progress in barium zirconate proton conductors for electrochemical hydrogen device applications: A review

Electrochemical hydrogen devices like fuel cells are widely investigated as promising technologies to mitigate the rising environmental challenges and enhance the renewable energy economy. In these devices, proton-conducting oxides (PCOs) are applied as electrolyte materials to transport protons. Excellent physical stability and higher proton transport number are two essential properties of electrolyte materials. Doped BaZrO₃ (BZO) is a solid ion-conducting perovskite material with high chemical stability and good proton-conducting properties at an intermediate temperature range of 400–650 °C. Therefore, BZO is an attractive material among the exciting proton-conducting oxides as electrolyte material. To enhance the proton transport properties and improve the material fabrication process of BZO, techniques such as the use of dopants, sintering aid, synthesis methods are crucial. The present review work highlights the applications of BZO as electrolyte material in electrochemical hydrogen devices such as hydrogen isotopes separation systems, hydrogen sensors, hydrogen pumps, and protonic ceramic fuel cells (PCFCs) or solid oxide fuel cells (SOFCs). The central section of this review summarizes the recent research investigations of these applications and provides a comprehensive insight into the various synthesis process, doping, sintering aid, operating environments, and operating condition's impact on the composition, morphology, and performance of BZO electrolyte materials. Based on the reviewed literature, remarks on current challenges and prospects are provided. The presented information on in-depth analysis of the physical properties of barium zirconate electrolyte's along with output performance will guide aspirants in conducting research further on this field.     

微氧技术在废水生物处理中的应用研究进展

在水污染日益严重和能源愈来愈紧缺的今天,低耗高效的污水处理技术的重要性越来越凸显。微氧技术因其能耗低、菌群种类复杂、物质转化和能量代谢多样化及去除复杂污染物效果好受到研究者的广泛关注。研究和工程实践表明,微氧条件与不同工艺的有机结合赋予了微氧技术新的作用和更丰富的内涵。从微氧与水解酸化、UASB、EGSB以及膜生物等不同技术的结合介绍了微氧技术在污水生物处理中的技术特点和应用。     

超重力反应强化技术最新进展

由于可数量级强化传质和分子混合过程,超重力技术成为最受关注的化工过程强化技术之一。综述了北京化工大学教育部超重力工程研究中心近几年在超重力反应器基础研究及超重力反应强化技术在硫化氢脱除、氧化、卤化等方面的研究进展及工业应用情况,并对超重力反应强化技术的发展趋势进行了展望。     

Microfluidic extraction using two phase laminar flow for chemical and biological applications

We review the state of the art in microfluidic separation technique based two-phase laminar flow with an application focus on chemical and biological sample. As we describe herein, two-phase laminar flow in the microfluidic extraction has several biological and engineering advantages over other methods including high reproducibility, biocompatibility, and selectivity. We review advances in applications of two-phase laminar flow and examine key parameters such as flow rate, phase composition, and surface charge property, how these can affect extract performance with the technology including microfluidic separation system. A special technology focus is given to emerging novel integrative microfluidic extraction, which aims to merge aqueous phase laminar flow and electric field technologies into simple packages. We conclude with a brief discussion of some of the emerging challenges in the field and some of the approaches that are likely to enhance their application.     

Environmental applications of biosurfactants: recent advances

Increasing public awareness of environmental pollution influences the search and development of technologies that help in clean up of organic and inorganic contaminants such as hydrocarbons and metals. An alternative and eco-friendly method of remediation technology of environments contaminated with these pollutants is the use of biosurfactants and biosurfactant-producing microorganisms. The diversity of biosurfactants makes them an attractive group of compounds for potential use in a wide variety of industrial and biotechnological applications. The purpose of this review is to provide a comprehensive overview of advances in the applications of biosurfactants and biosurfactant-producing microorganisms in hydrocarbon and metal remediation technologies.     

生物脱氮技术的研究

废水生物脱氮已经成为水污染控制的一个重要研究方向.传统的生物脱氮采用的是硝化、反硝化工艺,但存在着很多问题.对短程硝化反硝化、同时硝化反硝化及厌氧氨氧化等生物脱氮新技术的研究和开发进展进行了简单的综述和讨论,并指出了这些新技术的特点和研究开发应用的前景.