Search query: Water treatment

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abstract: Advanced oxidation processes via semiconductor photocatalysis for water treatment have been the subject of extensive research over the past three decades, producing many scientific reports focused on elucidating mechanisms and enhancing kinetics for the treatment of contaminants in water. Many of these reports imply that the ultimate goal of the research is to apply photocatalysis in municipal water treatment operations. However, this ignores immense technology transfer problems, perpetuating a widening gap between academic advocation and industrial application. In this Feature, we undertake a critical examination of the trajectory of photocatalytic water treatment research, assessing the viability of proposed applications and identifying those with the most promising future. Several strategies are proposed for scientists and engineers who aim to support research efforts to bring industrially relevant photocatalytic water treatment processes to fruition. Although the reassessed potential may not live up to initial academic hype, an unfavorable assessment in some areas does not preclude the transfer of photocatalysis for water treatment to other niche applications as the technology retains substantive and unique benefits.
author_names: Stephanie K Loeb

Pedro J J Alvarez

Jonathon Brame

Ezra L Cates

Wonyong Choi

John C Crittenden

Dionysios D Dionysiou

Qilin Li

Gianluca Li-Puma

Xie Quan

David L Sedlak

T David Waite

Paul K Westerhoff

Jae-Hong Kim
title: The Technology Horizon for Photocatalytic Water Treatment: Sunrise or Sunset?
venue: Environmental science technology
year: 2019

abstract: Growing worldwide population, climate change, and decaying water infrastructure have all contributed to a need for a better water treatment and conveyance model. Distributed water treatment is one possible solution, which relies on the local treatment of water from various sources to a degree dependent on its intended use and, finally, distribution to local consumers. This distributed, fit for purpose water treatment strategy requires the development of new modular point of use and point of entry technologies to bring this idea to fruition. Electrochemical technologies have the potential to contribute to this vision, as they have several advantages over established water treatment technologies. Electrochemical technologies have the ability to simultaneously treat multiple classes of contaminants through the in situ production of chemicals at the electrode surfaces with low power and energy demands, thereby allowing the construction of compact, modular water treatment technologies that require little maintenance and can be easily automated or remotely controlled. In addition, these technologies offer the opportunity for energy recovery through production of fuels at the cathode, which can further reduce their energy footprint. In spite of these advantages, there are several challenges that need to be overcome before widespread adoption of electrochemical water treatment technologies is possible. This Account will focus primarily on destructive electrolytic technologies that allow for removal of water contaminants without the need for residual treatment or management. Most important to the development of destructive electrochemical technologies is a need to fabricate nontoxic, inexpensive, high surface area electrodes that have a long operational life and can operate without the production of unwanted toxic byproducts. Overcoming these barriers will decrease the capital costs of water treatment and allow the development of the point of use and point of entry technologies that are necessary to promote more sustainable water treatment solutions. However, to accomplish this goal, a reprioritization of research is needed. Current research is primarily focused on investigating individual contaminant transformation pathways and mechanisms. While this research is important for understanding these technologies, additional work is needed in developing inexpensive, high surface area, stable electrode materials, minimizing toxic byproduct formation, and determining the life cycle and technoeconomic analyses necessary for commercialization. Better understanding of these critical research areas will allow for strategic deployment of electrochemical water treatment technologies to promote a more sustainable future.
author_names: Brian P Chaplin
title: The Prospect of Electrochemical Technologies Advancing Worldwide Water Treatment.
venue: Accounts of chemical research
year: 2019

abstract: In recent years, semiconductor photocatalytic process has shown a great potential as a low cost, environmental friendly and sustainable treatment technology to align with the "zero" waste scheme in the water/wastewater industry. The ability of this advanced oxidation technology has been widely demonstrated to remove persistent organic compounds and microorganisms in water. At present, the main technical barriers that impede its commercialisation remained on the post recovery of the catalyst particles after water treatment. This paper reviews the recent R&D progresses of engineered photocatalysts, photoreactor systems, and the process optimizations and modellings of the photooxidation processes for water treatment. A number of potential and commercial photocatalytic reactor configurations are discussed, in particular the photocatalytic membrane reactors. The effects of key photoreactor operation parameters and water quality on the photo process performances in terms of the mineralization and disinfection are assessed. For the first time, we describe how to utilize a multi variables optimization approach to determine the optimum operation parameters so as to enhance process performance and photooxidation efficiency. Both photomineralization and photo disinfection kinetics and their modellings associated with the photocatalytic water treatment process are detailed. A brief discussion on the life cycle assessment for retrofitting the photocatalytic technology as an alternative waste treatment process is presented. This paper will deliver a scientific and technical overview and useful information to scientists and engineers who work in this field.
author_names: Meng Nan Chong

Bo Jin

Christopher W K Chow

Christopher P Saint
title: Recent developments in photocatalytic water treatment technology: a review.
venue: Water research
year: 2010

abstract: Natural organic matter (NOM) is a complex matrix of organic substances produced in (or channeled to) aquatic ecosystems via various biological, geological and hydrological cycles. Such variability is posing a serious challenge to most water treatment technologies, especially the ones designed to treat drinking water supplies. Lately, in addition to the fluctuating composition of NOM, a substantial increase of its concentration in fresh waters, and also municipal wastewater effluents, has been reported worldwide, which justifies the urgent need to develop highly efficient and versatile water treatment processes. Coagulation is among the most applied processes for water and wastewater treatment. The application of coagulation to remove NOM from drinking water supplies has received a great deal of attention from researchers around the world because it was efficient and helped avoiding the formation of disinfection by products (DBPs) Nonetheless, with the increased fluctuation of NOM in water (concentration and composition) the efficiency of conventional coagulation was substantially reduced, hence the need to develop enhanced coagulation processes by optimizing the operating conditions (mainly the amount coagulants and pH) developing more efficient inorganic or organic coagulants, as well as coupling coagulation with other water treatment technologies. In the present review, recent research studies dealing with the application of coagulation for NOM removal from drinking water supplies are presented and compared. In addition, integration schemes combining coagulation and other water treatment processes are presented, including membrane filtration, oxidation, adsorption and others processes.
author_names: Mika Sillanpaa

Mohamed Chaker Ncibi

Anu Matilainen

Mikko Vepsalainen
title: Removal of natural organic matter in drinking water treatment by coagulation: A comprehensive review.
venue: Chemosphere
year: 2018

abstract: The global presence of microplastic (MP) in aquatic ecosystems has been shown by various studies. However, neither MP concentrations nor their sources or sinks are completely known. Waste water treatment plants (WWTPs) are considered as significant point sources discharging MP to the environment. This study investigated MP in the effluents of 12 WWTPs in Lower Saxony, Germany. Samples were purified by a plastic preserving enzymatic oxidative procedure and subsequent density separation using a zinc chloride solution. For analysis, attenuated total reflection Fourier transform infrared spectroscopy (ATR FT IR) and focal plane array (FPA) based transmission micro FT IR imaging were applied. This allowed the identification of polymers of all MP down to a size of 20 mm. In all effluents MP was found with quantities ranging from 0 to 5 x 101 m 3 MP 500 mm and 1 x 101 to 9 x 103 m 3 MP 500 mm. By far, polyethylene was the most frequent polymer type in both size classes. Quantities of synthetic fibres ranged from 9 x 101 to 1 x 103 m 3 and were predominantly made of polyester. Considering the annual effluxes of tested WWTPs, total discharges of 9 x 107 to 4 x 109 MP particles and fibres per WWTP could be expected. Interestingly, one tertiary WWTP had an additionally installed post filtration that reduced the total MP discharge by 97% Furthermore, the sewage sludge of six WWTPs was examined and the existence of MP, predominantly polyethylene, revealed. Our findings suggest that WWTPs could be a sink but also a source of MP and thus can be considered to play an important role for environmental MP pollution.
author_names: Svenja M Mintenig

Ivo Int-Veen

Martin G J Loder

Sebastian Primpke

Gunnar Gerdts
title: Identification of microplastic in effluents of waste water treatment plants using focal plane array based micro Fourier transform infrared imaging.
venue: Water research
year: 2017

abstract: Centralized water treatment has dominated in developed urban areas over the past century, although increasing challenges with this model demand a shift to a more decentralized approach wherein advanced oxidation processes (AOPs) can be appealing treatment options. Efforts to overcome the fundamental obstacles that have thus far limited the practical use of traditional AOPs, such as reducing their chemical and energy input demands, target the utilization of heterogeneous catalysts. Specifically, recent advances in nanotechnology have stimulated extensive research investigating engineered nanomaterial (ENM) applications to AOPs. In this Perspective, we critically evaluate previously studied ENM catalysts and the next generation treatment technologies they seek to enable. Opportunities for improvement exist at the intersection of materials science and treatment process engineering, as future research should aim to enhance catalyst properties while considering the unique roadblocks to practical ENM implementation in water treatment.This Perspective evaluates catalysts based on engineered nanomaterials and the next generation water treatment technologies they seek to enable.
author_names: Brenna C Hodges

Ezra L Cates

Jae-Hong Kim
title: Challenges and prospects of advanced oxidation water treatment processes using catalytic nanomaterials
venue: Nature Nanotechnology
year: 2018

abstract: Abstract Nitrate contamination in surface and ground waters is one of this century's major engineering challenges due to negative environmental impacts and the risk to human health in drinking water. Electrochemical reduction is a promising water treatment technology to manage nitrate in drinking water. This critical review describes the fundamental principles necessary to understand electrochemical reduction technologies and how to apply them. The focus is on electrochemical nitrate reduction mechanisms and pathways that form undesirable products (nitrite, ammonium) or the more desirable product (dinitrogen) Factors influencing the conversion rates and selectivity of electrochemical nitrate reduction, such as electrode material and operating parameters, are also described. Finally, the applicability for treating drinking water matrices using electrochemical processes is analyzed, including existing implementation of commercial treatment systems. Overall, this critical review contributes to the understanding of the potential applications and constraints of electrochemical reduction to manage nitrate in drinking waters and highlights directions for future research required for implementation.
author_names: Sergi Garcia-Segura

Mariana Lanzarini-Lopes

Kiril D Hristovski

Paul K Westerhoff
title: Electrocatalytic reduction of nitrate: Fundamentals to full scale water treatment applications
year: 2018

abstract: Solar steam generation is emerging as promising solar energy conversion technology for potential applications in desalination, sterilization and chemical purification. Despite the recent use of photon management and thermal insulation, achieving optimum solar steam efficiency requires simultaneous minimization of radiation, convection and conduction losses without compromising light absorption. Inspired by the natural transpiration process in plants, here we report a 3D artificial transpiration device with all three components of heat loss and angular dependence of light absorption minimized, which enables over 85% solar steam efficiency under one sun without external optical or thermal management. It is also demonstrated that this artificial transpiration device can provide a complementary path for waste water treatment with a minimal carbon footprint, recycling valuable heavy metals and producing purified water directly from waste water contaminated with heavy metal ions.
author_names: Xiuqiang Li

Renxing Lin

George Ni

Ning Xu

Xiaozhen Hu

Bin Zhu

Guangxin Lv

Jinlei Li

Shining Zhu

Jia Zhu
title: Three dimensional artificial transpiration for efficient solar waste water treatment
year: 2018

abstract: The high concentrations of pharmaceuticals and personal care products (PPCP) that found in water in many locations are of concern. Among the available water treatment methods, heterogeneous photocatalysis using TiO2 is an emerging and viable technology to overcome the occurrence of PPCP in natural and waste water. The combination of carbonaceous materials (e.g. activated carbon, carbon nanotubes and graphene nanosheets) with TiO2, a recent development, gives significantly improved performance. In this article, we present a critical review of the development and fabrication of carbonaceous TiO2 and its application to PPCP removal including its influence on water chemistry, and the relevant operational parameters. Finally, we present an analysis of current priorities in the ongoing research and development of carbonaceous TiO2 for the photodegradation of PPCP.
author_names: Dion Awfa

Mohamed Ateia

Manabu Fujii

Matthew Stanley Johnson

Chihiro Yoshimura
title: Photodegradation of pharmaceuticals and personal care products in water treatment using carbonaceous TiO2 composites: A critical review of recent literature.
venue: Water research
year: 2018

abstract: Electrocoagulation is an effective electrochemical approach for the treatment of different types of contaminated water and has received considerable attention in recent years due its high efficiency in dealing with numerous stubborn pollutants. It has been successful in dealing with organic and inorganic contaminants with negligible or almost no generation of by product wastes. During the past decade, vast amount of research has been devoted to utilizing electrocoagulation for the treatment of several types of wastewater, ranging from polluted groundwater to highly contaminated refinery wastewater. This paper offers a comprehensive review of recent literature that has been dedicated to utilizing electrocoagulation for water treatment, focusing on current successes on specific applications in water and wastewater treatment, as well as potentials for future applications. The paper examines such aspects as theory, potential applications, current challenges, recent developments as well as economical concerns associated with the technology. Most of the recent EC research has been focusing on pollutant specific evaluation without paying attention to cell design, process modeling or industrial applications. This review attempts to highlight the main achievements in the area and outlines the major shortcomings with recommendations for promising research options that can enhance the technology and broaden its range of applications.
author_names: Dina T Moussa

Muftah H El-Naas

Mustafa S Nasser

Mohammed J Al-Marri
title: A comprehensive review of electrocoagulation for water treatment: Potentials and challenges.
venue: Journal of environmental management
year: 2017