Mohammad Mehdi Golbini Mofrad; Mika Sillanpää; Iman Parseh; Afshin Ebrahimi; Mohammad Mehdi Amin
Abstract
Background: Treating working fluid wastewater (WFW) by having several organic/inorganic pollutants is not an easy task. There are many hurdles to adopt an appropriate treatment strategy through biological, physical, chemical, and electrochemical approaches. Methods: The treatment methods of WFW are reviewed ...
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Background: Treating working fluid wastewater (WFW) by having several organic/inorganic pollutants is not an easy task. There are many hurdles to adopt an appropriate treatment strategy through biological, physical, chemical, and electrochemical approaches. Methods: The treatment methods of WFW are reviewed in this work through a critical literature survey. Therefore, databases such as Google scholar, science direct, and PubMed were considered to find literature. Altogether, about 49 articles were finally found relevant to the topic to extract and interpret findings. Results: The best solution to treat WFW could be an integrated approach by designing various AOPs for the pre-treatment and post-treatment of main units. For this reason, and to meet discharge standards, measuring intermediates and the toxicity of reaction solution and final effluent by bioassay could be a complementary tool. Additionally, if the used AOP is a photocatalytic one, applying catalysts with a low energy bandgap and designing reactors to utilize the highest amount of energy is crucial to make a process cost-effective. Furthermore, using aeration could increase the number of radicals by supplying oxygen and removing contaminants from the reaction medium. Finally, if AOPs are the pretreatment unit, removing halogens should be done to predict floc breakage in the next step. Conclusion: Hybrid treatment approaches with at least 80% efficiency in degrading and removing micropollutants could be reliable methods to dispose of working fluid wastewater. However, further research on them in the future is essential because of discharging a considerable volume of them annually worldwide.
Mohammad Ali Baghapour; Mansooreh Dehghani; zahra elhamiyan
Volume 4, Issue 1 , January 2016, , Pages 14-21
Abstract
AbstractBackground: Dyes are visible materials and are considered as one of the hazardous components that make up the industrial waste. Dye compounds in natural water, even in very low concentrations, will lead to environmental problems. Azo dyes are compounds with one or more –N=N– groups and are ...
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AbstractBackground: Dyes are visible materials and are considered as one of the hazardous components that make up the industrial waste. Dye compounds in natural water, even in very low concentrations, will lead to environmental problems. Azo dyes are compounds with one or more –N=N– groups and are used in textile industry. Because of its low price, solubility, and stability, azo dyes are widely used in the textile industry. Direct Red 81 (DR81) is one of the azo dyes, which is removed from bodies of water, using various methods. This study aimed to assess DR81 dye removal by Fenton oxidation and the effects of various parameters on this process.Methods: Decolorization tests by Fenton oxidation were performed at dye concentrations of 50, 500, 100 and 1000 mg/L; hydrogen peroxide concentrations of 0, 10, 30, 60 and 120 mg/L; iron (II) sulfate heptahydrate concentrations of 0, 3, 5, 20 and 50 mg/L; and pH levels of 3, 5, 7 and 10 for durations of 5, 10, 20, 30, 60 and 180 minutes.Results: The optimal condition occurred at a dye concentration of 20 mg/L, hydrogen peroxide concentration of 120 mg/L, bivalent iron concentration of 100 mg/L, pH of 3, and duration of 30 minutes. Under such conditions, the maximum dye removal rate was 88.98%.Conclusion: The results showed that DR81 could be decomposed and removed by Fenton oxidation. In addition, the removal of Direct Red 81 (DR81) depends on several factors such as dye concentration, reaction time, concentrations of hydrogen peroxide and iron, and pH.