Addressing water scarcity: cationic polyelectrolytes in water treatment and purification

Synthetic cationic polyelectrolytes (CPEs) serve as coagulation and flocculation agents in wastewater treatment due to a synergy of inherent electrostatic interactions and hydrophilic properties. In wastewater treatment, CPEs act as coagulation and flocculation agents to aggregate impurities and enable water purification. New health and environmental‐related regulations provide motivation for government agencies and industrial companies to reuse wastewater. Chemical structure, molecular weight, charge density and functionality of CPEs provide tailorability for specific purification needs. Cationic polyacrylamides, ammonium‐based polymers, poly(allyldimethyl‐ammonium chloride) and epichlorohydrin/dimethylamine‐based polymers are the most common CPEs used as coagulation and flocculation agents because they are economical and water soluble with tunable charge densities at high molecular weights. Free radical polymerization, step‐growth polymerization and post‐polymerization modification methods afford each polymer system. This review highlights recent advancements in synthetic methods to yield CPEs, structure?property relationships as related to flocculation efficiency and a summary of their toxicity and environmental impact. © 2018 Society of Chemical Industry     

Costs of Advanced Treatment in Water Reclamation

The additional removal of trace organic contaminants (TOrCs) provided by advanced water and wastewater treatment inevitably requires additional financial costs, which must be estimated to support utility planning and compare alternatives. This study presents conceptual-level (Class 4) capital and annual operations and maintenance (O&M) cost curve equations to aid evaluations of advanced treatment trains for water reuse. The cost curve equations are broadly applicable to the water reuse community, particularly those interested in ozone-based treatment trains. Unit processes include microfiltration or ultrafiltration membranes (MF/UF), nanofiltration or reverse osmosis membranes (NF/RO), ozone (with or without hydrogen peroxide, H₂O₂), ultraviolet (UV) treatment with H₂O₂ (UV/H₂O₂), and biological activated carbon (BAC); all cost curves are for a unit process and can be added together to obtain costs for a combined treatment train. The cost curves indicate that at all plant capacities (1 to 500 MGD), membrane treatment (e.g., MF or RO) represents the highest cost unit process, ozone the least, and BAC or UV/H₂O₂ fall in between. Additionally, the relationship between ozone dose and TOrC removal is discussed with a demonstration of how costs change with increasing ozone dose to achieve desired TOrC destruction.     

生物吸附剂及其在重金属废水处理中的应用进展

重金属离子严重危害人体健康,因此在废水处理中必须将其去除。传统去除重金属离子的方法很多,但都存在某些不足,近年发展起来的生物吸附技术,在水处理领域具有很好的应用前景。综述了近年来生物吸附剂在重金属废水处理中的应用情况,同时探讨了今后生物吸附法去除重金属的发展趋势。     

Degradation of Aqueous Pharmaceuticals by Ozonation and Advanced Oxidation Processes: A Review

A vast number of pharmaceuticals have been detected in surface water and drinking water around the world, which indicates their ineffective removal from water and wastewater using conventional treatment technologies. Concerns have been raised over the potential adverse effects of pharmaceuticals on public health and aquatic environment. Among the different treatment options, ozonation and advanced oxidation processes are likely promising for efficient degradation of pharmaceuticals in water and wastewater. Recent progress of advanced oxidation of aqueous pharmaceuticals is reviewed in this paper. The pharmaceuticals and non-therapeutic medical agent of interest include antibiotics, anticonvulsants, antipyretics, beta-blockers, cytostatic drugs, H₂ antagonists, estrogenic hormone and contraceptives, blood lipid regulators, and X-ray contrast media.     

Recent advances in synthesis,characterization, and applications of nanoparticles for contaminated water treatment- A review

The major issue of consumable water shortage in different parts of the world has piqued the interest of researchers around the globe towards finding out novel, efficient and cost-effective means and techniques for treatment of contaminated water. Towards such efforts, researchers are experimenting with various types of nanoparticles for observing their abilities to treat polluted and/or wastewater. Numerous types of nanoparticles such as carbon-based nanoparticles, semiconductor nanoparticles, ceramic nanoparticles, polymeric nanoparticles, metal nanoparticles, magnetic nanoparticles, etc. are widely tested to confirm their applicability as potential candidates for contaminated as well as wastewater treatment. Different types of nanoparticles offer specific advantages depending on their composition, physical, chemical, electrical, magnetic and structural characteristics. Nanoparticles such as nanoferrites are reported to be easily separated, regenerated and reused up to several runs without incurring any loss in their properties which tend to significantly reduce operations costs. The present study provides a detailed review of the various synthesis and characterization techniques for the production of the nanoparticles. The present study also reviews the current progress, made particularly during the last two decades, in the application of nanoparticles for successful removal of organic, metallic as well as pathogenic pollutants from the water. This review aims to highlight the unlimited potential of nanoparticles and their derivatives in the domain of contaminated and wastewater treatment.     

Initiatives and strategies for development of nanotechnology in nations: a lesson for Africa and other least developed countries

It is a known fact that the progress and development of different nations of the world is strongly connected with the type of materials under their use. This paper highlighted the development of nanotechnology in some selected countries of the world through a careful review of their road maps by way of public and private initiatives, funding/investment profile, human resources development, industrial potentials, and focus in order to draw inferences. The peculiar challenges and opportunities for some African nations and other least developed countries (LDC) were drawn for their economic and technological developments. This investigation was simply based on open access literatures. The review showed that although nanotechnology is new globally, most countries of the world have had growing public and private investments aimed at bringing about new materials and systems that can impact positively on their economy and ensure their global competitiveness and sustainability. The global scenario suggests the crucial role of cooperation in a multidisciplinary collaboration/partnership between government ministries, agencies, institutions, and private sector/donor agencies in order to pool enough resource capital required for activities in nanotechnology.     

Aqueous Pesticide Degradation by Ozonation and Ozone-Based Advanced Oxidation Processes: A Review (Part II)

Pesticides are known to be persistent in surface water and groundwater supplies and as a result, their existence in these water sources has been recognized as a major problem in many countries. The occurrence of these persistent pesticides in water bodies can also cause potential adverse public and environmental health effects. Among many water and wastewater treatment options, ozonation and ozone-based advanced oxidation processes, such as ozone/hydrogen peroxide, ozone/ultraviolet irradiation, and ozone/hydrogen peroxide/ultraviolet irradiation, possess a high potential for degrading and detoxifying these pollutants in water and wastewater. In this paper, ozone based treatment of four major groups of pesticides, namely aniline-based compounds, pyridines and pyrimidines, triazines, and substituted ureas, as well as that of several miscellaneous pesticides are reviewed. Degree of pesticide degradation, reaction kinetics, identity and characteristics of degradation by-products, and possible degradation pathways are covered and discussed.     

Integrated concepts in water reuse: managing global water needs

Communities across the world face water supply challenges due to increasing demand, drought, depletion and contamination of groundwater, and dependence on single sources of supply. Water reclamation, recycling, and reuse address these challenges by resolving water resource issues and creating new sources of high-quality water supplies. The future potential for reclaimed treated effluent is enormous. Although water reclamation and reuse is practiced in many countries around the world, current levels of reuse constitute a small fraction of the total volume of municipal and industrial effluent generated. In addition, to meet their growing water supply needs, communities are considering other non-traditional sources of water such as agricultural return flows, concentrate and other wastewater streams, storm water, co-produced water resulting from energy and mining industries, as well as the desalination of seawater and brackish groundwater. Water reuse provides a wide range of benefits for communities, which translates into creating immense value for the public and the environment. The benefits of water reuse, however, can be difficult to quantify and often go unrecognized. One of the most significant benefits of water reuse is the value created by the inclusion of water reuse in integrated water resources planning and other aspects of water policy and the implementation of water projects resulting in the long-term sustainability of our water supplies. These integrated concepts, which involve the convergence of diverse areas such as governance, health risks, regulation, and public perception, also present a significant challenge to water reuse. These complex connections can assert equal influences on both the benefits and challenges associated with water reuse. In addressing these complex integrated issues, a number of significant barriers and impediments to the widespread implementation of water reuse projects arise. Numerous examples exist of barriers experienced by current water reuse projects around the world, including: the need for innovative technologies, technology transfer, and novel applications; the need for public education and increased public acceptance; better documentation of the benefits of water reuse; the lack of available funding for water reuse projects; working with the media; and the need for support by regulators and politicians. Integrated concepts can also be factors in a number of trends affecting water reuse globally. Current trends include addressing emerging pollutants of concern, the use of advanced wastewater treatments including membranes, indirect potable reuse, public perception, understanding the economics of water reuse, groundwater recharge and aquifer storage and recovery, salinity management (including concentrate disposal), increase in the use of “alternative sources”, environmental or natural system restoration, innovative uses of nonpotable water reuse, and decentralized and satellite systems. Since these trends are emerging developments in the field of water reclamation and reuse, there are a number of research needs associated with these topics. Research is needed to better understand the issues, to develop innovative technologies, and to develop tools and other assistance for communities and water agencies to implement successful water reclamation and reuse projects.     

煤化工废水中油、酚、氨回收研究进展

煤化工废水水量大,水质复杂,化学需氧量（COD）最高可达30000mg/L,是一种典型的处理难度高的工业废水。油类物质、酚类物质以及氨氮是煤化工废水中污染物质的主要组成成分,其最高浓度分别可达10000mg/L、9000mg/L、4000mg/L。如果不回收,则造成资源的严重浪费。因此,油类物质、酚类物质以及氨氮的有效回收是实现煤化工废水无害化处理不容忽视的问题。本文主要从油类物质、酚类物质、氨氮的回收技术与工艺3个方面梳理了国内外煤化工废水中油类物质、酚类物质以及氨氮的回收现状,并对各类技术的优缺点进行了对比和分析,其目的是让该领域的研究人员以更加科学的方法了解煤化工废水中油类物质、酚类物质以及氨氮的研究现状与发展趋势。最后基于节能、高效、持续健康的发展理念,探讨了未来煤化工废水中油类物质、酚类物质以及氨氮回收的前景。     

Corrosion resistance of stainless steels in chloride containing supercritical water oxidation system

As the science and process applications of supercritical water (SCW) and supercritical water oxidation (SCWO) become more thoroughly understood, it is logical to envision the use of the SCWO process by diverse industries and public wastewater and sludge generators. This technology can be adapted to accomplish either pre or end-of-pipe wastewater treatment. There is a need to destroy both military and civilian hazardous waste, and urgency, mandated by public concern over traditional waste handling methodologies, to identify safe and efficient alternative technologies. By capitalizing on the properties of water above its critical point, 374 °C and 22.4 MPa for pure water, this technology provides rapid and complete oxidation with high destruction efficiencies at typical operating temperatures. Nevertheless, corrosion of the materials of fabrication is a serious concern. While iron-based alloys and nickel-based alloys are generally considered important for service applications, results from laboratory and pilot-scale SCWO systems presently in operation indicate that they will not withstand some aggressive feeds. Significant weight loss and localized effects, including stress corrosion cracking (SCC) and dealloying, are seen in chlorinated environments. This work assesses the corrosion characteristics of iron-based stainless steels exposed to high supercritical temperatures in a chlorinated military waste containing salts.     

Nanomaterial processing strategies in functional hybrid materials for wastewater treatment using algal biomass

Algal cultivation has tremendous potential in wastewater treatment, and its simultaneous biomass production has advantages for the production of value added products such as biodiesel, fertilizers and pharmaceuticals. Some obstacles to obtaining a productive biological water treatment and bioenergy system are the harvesting and processing of biomass. Such issues can be addressed using nano‐bio hybridization approaches by simplifying the microbial harvesting step along with increasing the efficiency of wastewater treatment. This review highlights studies within our research group that are based on the fabrication of functional hybrid materials using algal biomass, including: (i) electrospun nanofibers; (ii) laminar nanomaterials; and (iii) magnetic nanoparticles impregnated in a polymer. All of these techniques have been used for the removal of waste pollutants such as nitrate and phosphate ions. The multidisciplinary techniques have potential to provide effective algal culture systems for industrial applications, while having a significant impact on wastewater treatment. © 2017 Society of Chemical Industry     

Wastewater management in Greater Buenos Aires,Argentina

The city of Buenos Aires, the capital town of Argentina, is located besides De la Plata river, and is surrounded by a continuum of built areas, the so-called Greater Buenos Aires. The present situation of sewerage system is described and analysed taking into account: distance from Buenos Aires city, geographic location, socio-economic level, wastewater treatment technologies, management and regulatory agencies. The existence of a sewerage system does not mean automatically wastewater treatment, as frequently in Latin America. The water quality of wastewater receiving bodies is a matter of increasing concern, since large quantity of pollutants is daily discharged.     

A comprehensive review of nanofiltration membranes:Treatment, pretreatment, modelling, and atomic force microscopy

Nanofiltration membranes (NF) have applications in several areas. One of the main applications has been in watertreatment for drinking water production as well as wastewater treatment. NF can either be used to treat all kinds of water including ground, surface, and wastewater or used as a pretreatment for desalination. The introduction of NF as a pretreatment is considered a breakthrough for the desalination process. NF membranes have been shown to be able to remove turbidity, microorganisms and hardness, as well as a fraction of the dissolved salts. This results in a significantly lower operating pressure and thus provides a much more energy-efficient process. Similar to other membrane processes, a major problem in NF membrane applications is fouling. Several studies have investigated the mechanisms of fouling in NF membranes and suggested methods to minimize and control the fouling of NF membranes. For NF membrane characterizations and process prediction, modeling of NF processes and the use of atomic force microscopy (AFM) are very important. The ability to predict the performance of NF processes will lead to a lower number of experiments, saving of time and money, and help to understand the separation mechanisms during NF. A comprehensive review of NF in water treatments is presented including a review of the applications of NF in treating water as well as in the pretreatment process for desalination; the mechanism as well as minimization of NF membrane fouling problems; and theories for modelling and transport of salt, charged and noncharged organic compounds in NF membranes. The review will also address the application of AFM in studying the morphology of membrane surfaces as part of the NF membrane characterization.     

我国煤化工废水零排放的实践困境与出路

介绍了煤化工废水零排放方案面临的困境,指出废水零排放存在非正常工况废水水质波动大、中水平衡调度困难、能耗指标高、潜在二次污染转移等诸多问题。建议从稳定生产工艺前端入手,提高水循环利用水平,实现废水处理工艺能力的匹配,增加废水回用点,由"定点回用"改为"一水多用",以强化风险防范,并切实加强对煤化工废水零排放项目的规范引导。     

生物法除去废水中硝酸盐的研究进展

废水中的硝酸盐给人类及动物带来了不利的影响而受到日益重视,生物反硝化脱氮法可以很好地将硝酸盐化合物还原为对人类无害的氮气.首先叙述水污染物硝酸盐以及由其引起的一系列问题,然后再讨论除去硝酸盐的各种方法和研究进展,最后,介绍一种有效的处理各种不同含氮废水的方法--生物电化学脱氮法.     

State-of-the-art technology: Recent investigations on laser-mediated synthesis of nanocomposites for environmental remediation

In both developing and industrialized/developed countries, various hazardous/toxic environmental pollutants are entering water bodies from organic and inorganic compounds (heavy metals and specifically dyes). The global population is growing whereas the accessibility of clean, potable and safe drinking water is decreasing, leading to world deterioration in human health and limitation of agricultural and/or economic development. Treatment of water/wastewater (mainly industrial water) via catalytic reduction/degradation of environmental pollutants is extremely critical and is a major concern/issue for public health. Light and/or laser ablation induced photocatalytic processes have attracted much attention during recent years for water treatment due to their good (photo)catalytic efficiencies in the reduction/degradation of organic/inorganic pollutants. Pulsed laser ablation (PLA) is a rather novel catalyst fabrication approach for the generation of nanostructures with special morphologies (nanoparticles (NPs), nanocrystals, nanocomposites, nanowires, etc.) and different compositions (metals, alloys, oxides, core-shell, etc.). Laser ablation in liquid (LAL) is generally considered a quickly growing approach for the synthesis and modification of nanomaterials for practical applications in diverse fields. LAL-synthesized nanomaterials have been identified as attractive nanocatalysts or valuable photocatalysts in (photo)catalytic reduction/degradation reactions. In this review, the laser ablation/irradiation strategies based on LAL are systematically described and the applications of LAL synthesized metal/metal oxide nanocatalysts with highly controlled nanostructures in the degradation/reduction of organic/inorganic water pollutants are highlighted along with their degradation/reduction mechanisms.     

The potential application of natural zeolite for greywater treatment

Natural zeolites are good potential material for water and wastewater treatment. It is due to the advantages of low cost, ion-exchange and adsorption capability of the natural zeolites. It can also be modified and regenerated. This paper thus looks at efforts made in exploring the potential application of natural zeolites and modified natural zeolites in water and wastewater treatment especially for reducing or removing contaminants in greywater, a type of wastewater originated from bathrooms and laundries in household. The material to be reviewed in this paper includes (i) major greywater contaminants and (ii) the potential of natural zeolites for greywater treatment.     

聚硅酸盐类絮凝剂的研究进展

从聚硅酸盐类絮凝剂研制与发展新经历的４个阶段,概略评术字国内外的研究现状及其进展,分析了各类聚硅酸盐絮凝剂,指出了目前研究中所存在的问题。建议今后聚硅酸盐类絮凝的研究应重点开展;制备新工艺研究,提高产品的絮凝及稳定性;聚硅酸与金属盐之间的相互作用研究,探讨絮凝机理;进一步开展应用研究,确定水处理中的最佳应用和范围。     

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.