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Nanotechnology for the treatment of industrial-scale effluents – particularly the removal of organic contaminants from textile effluents using nano-TiO2
Expanded Title:Suitable quality water is essential for life and industrial productivity. The only two options available are to purify available seawater on the planet to produce more potable water but ideally, to conserve and reuse the available water. The textile industry is one of the most chemically intensive industries on earth, using more than 100,000 types of chemicals and the number one polluter of potentially potable water internationally. The aim of this project was to assess the application of one of the emerging nanotechnologies for water treatment, namely, nanofiltration and nanophotocatalytic treatment of the nanofilter retentate. The objectives of this work were: (1) To conduct a stream segregation scoping assessment a cleaner production effluent audit for a proposed wastewater treatment process at the Falke Eurosocks, (2) To design, build and evaluate a pilot scale rig for the treatment of textile effluent using pre-filtration,ultrafiltration and nanofiltration, (3) To develop synthesis strategies for production of controlled sized titanium dioxide nanophotocatalyst powders, (4) To develop and optimize technology to treat effluent using immobilised titanium dioxide nanoparticles under daylight in a trickle-bed reactor, and (5) To evaluate the performance of the nanofiltration and photocatalysis of real textile effluent. This report presents results for the treatment of commercial textile effluents using nanofiltration and photocatalysis using nano-titanium dioxide. The stream segregation audit revealed that the installation of three-way valves into the existing piping systems can easily facilitate separation of waste streams for treatment and reuse. Boiler water and condensate can be treated and separated from the dye vat effluents. This will reduce the footprint of the final effluent treatment plant. Several strategies were developed for the local production of nano-titanium dioxide powders for use in photocatalysis. Existing sol-gel methods were improved. Robust process conditions were established for the production of sub-10 nm particles using continuous hydrothermal synthesis to produce multi-polymorph anatase-rich nano-titanium dioxide. These results are very encouraging showing the possibilities for locally manufactured photocatalysts to be used in the treatment of textile effluents. Various methods of immobilising nano-titanium dioxide were evaluated. The industrial potential for the utilisation of the nano-titanium dioxide immobilisation techniques developed in this work is great since there is a nanofibre spinning company in Cape Town able to produce large mats that could be incorporated in a multistage thin film fixed bed photocatalytic reactor for upscaling of the process using artificial and/or natural sunlight. An ultrafiltration / nanofiltration pilot effluent treatment plant was designed and installed at the factory. Under the current conditions, 50% of water could be recovered as the nanofiltration permeate. The colour was successfully removed from the nanofiltration brine during treatment using standard conditions under which the sample was only treated for 90 minutes; if treatment time is increased, further removal of COD and TOC could be achieved. The inorganic ions can be recovered during a further treatment step.
Date Published:01/06/2017
Document Type:Research Report
Document Subjects:Wastewater Management - Industrial
Document Keywords:Pollution control
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:2386/1/16
ISBN No:978-1-4312-0901-
Authors:Greyling CJ; Fester VG; Ngila JC; Chaúque EFC; Edwards W
Project No:K5/2386
Originator:WRC
Organizations:Cape Peninsula University of Technology; University of Johannesburg; ATL Hydro Pty Ltd
Document Size:5 716 KB
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