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: 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: As emerging contaminants, antibiotic resistance genes (ARGs) have become a public concern. This study aimed to investigate the occurrence and diversity of ARGs, and variation in the composition of bacterial communities in source water, drinking water treatment plants, and tap water in the Pearl River Delta region, South China. Various ARGs were present in the different types of water. Among the 27 target ARGs, floR and sul1 dominated in source water from three large rivers in the region. Pearson correlation analysis suggested that sul1, sul2, floR, and cmlA could be potential indicators for ARGs in water samples. The total abundance of the detected ARGs in tap water was much lower than that in source water. Sand filtration and sedimentation in drinking water treatment plants could effectively remove ARGs; in contrast, granular activated carbon filtration increased the abundance of ARGs. It was found that Pseudomonas may be involved in the proliferation and dissemination of ARGs in the studied drinking water treatment system. Bacteria and ARGs were still present in tap water after treatment, though they were significantly reduced. More research is needed to optimize the water treatment process for ARG removal.
author_names: Hao-Chang Su

You-sheng Liu

Chang-Gui Pan

Jun Chen

Liang-Ying He

Guang-Guo Ying
title: Persistence of antibiotic resistance genes and bacterial community changes in drinking water treatment system: From drinking water source to tap water.
venue: The Science of the total environment
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: High silica zeolites have been found to be effective adsorbents for the removal of organic micro pollutants (OMPs) from impaired water, including various pharmaceuticals, personal care products, industrial chemicals, etc. In this review, the properties and fundamentals of high silica zeolites are summarised. Recent research on mechanisms and efficiencies of OMP adsorption by high silica zeolites are reviewed to assess the potential opportunities and challenges for the application of high silica zeolites for OMP adsorption in water treatment. It is concluded that the adsorption capacities are well related to surface hydrophobicity/hydrophilicity and structural features, e.g. micropore volume and pore size of high silica zeolites, as well as the properties of OMPs. By using high silica zeolites, the undesired competitive adsorption of background organic matter (BOM) in natural water could potentially be prevented. In addition, oxidative regeneration could be applied on site to restore the adsorption capacity of zeolites for OMPs and prevent the toxic residues from re entering the environment.
author_names: Na Jiang

Ran Shang

Sebastiaan G J Heijman

Luuk C Rietveld
title: High silica zeolites for adsorption of organic micro pollutants in water treatment: A review.
venue: Water research
year: 2018

abstract: Continuous flow photochemistry in microreactors receives a lot of attention from researchers in academia and industry as this technology provides reduced reaction times, higher selectivities, straightforward scalability, and the possibility to safely use hazardous intermediates and gaseous reactants. In this review, an up to date overview is given of photochemical transformations in continuous flow reactors, including applications in organic synthesis, material science, and water treatment. In addition, the advantages of continuous flow photochemistry are pointed out and a thorough comparison with batch processing is presented.
author_names: Dario Cambie

Cecilia Bottecchia

Natan J W Straathof

Volker Hessel

Timothy Noel
title: Applications of Continuous Flow Photochemistry in Organic Synthesis, Material Science, and Water Treatment.
venue: Chemical reviews
year: 2016

abstract: Abstract The utilization of solar energy to drive water treatment processes is a potential sustainable solution to the world's water scarcity issue. In recent years, significant efforts have been devoted to developing and testing innovative solar based water treatment technologies, which are comprehensively reviewed in this paper. Recent developments and applications of seven major solar desalination technologies, solar photocatalysis process and solar disinfection are investigated. Potential integration of solar technologies and desalination processes are summarized. By collecting and analysing performance data from recent studies, the status of productivity, energy consumption and water production costs of different technologies is critically reviewed. The real world applicability as well as technical and economic feasibility is also evaluated. Presently, most of the solar water treatment processes are still under development with limited real applications. Economic competitiveness is among the major reasons that affect the scaling up and commercialization. It is revealed that the reported water costs of small to medium scale solar desalination plants are in the range of US$0.2 22/m3, much higher than conventional fossil fuel based plants. However, the estimated low water costs (US$0.9 2.2/m3) for large scale solar based plants indicate that solar based alternatives will become potentially viable in the near future.
author_names: Ying Zhang

Muttucumaru Sivakumar

Shu-Qing Yang

Keith Enever

Mohammad Ramezanianpour
title: Application of solar energy in water treatment processes: A review
year: 2018