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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/11907
Title: Chrome Removal from Wastewater Using Water Treatment Plant Sludge as an Adsorbent
???metadata.dc.contributor.*???: Belay Woldeyes (PhD)
Wegene, Deriba
Keywords: Alum based water treatment sludge;batch adsorption;response surface methodology;Cr(VI);fixed bed column
Issue Date: Jun-2015
Publisher: AAU
Abstract: Industries produces large amount of waste and the effluent of these wastes are often hazardous in polluting the environment and affecting human health. Tanneries are among industries which release large amount of waste which contains hazardous heavy metals such as chromium. Hexavalent chromium in the environment is often harmful and it should be treated before releasing to the environment. Chromium carcinogenicity to humans and other living organisms has promulgated extensive research on its treatment technologies with varying levels of success. The present study deals with removal of Cr(VI) by alum based water treatment sludge (Al- WTS) through batch and fixed bed column study. Response surface methodology (RSM) was applied in batch wise experiment for designing and analysis of experiment. Cr(VI) concentration and pH increase, is shown to decrease chrome removal percent, while adsorbent dose and shaking time increase, is shown to increase chrome removal. Factor interaction terms: Cr(VI) concentration with pH shows that maximum chrome removal 95.62.1% was obtained at Cr(VI) concentration of 2.4mg/l and pH 2.45, while interaction of Cr(VI) concentration and adsorbent dose shows, 97.06% chrome removal was obtained at chrome concentration of 3.3mg/L and adsorbent dose of 6.3g. Interaction of pH and adsorbent dose also shows that maximum chrome removal 92.2 was obtained at pH 2.44 and adsorbent dose of 6.17g. Theoretical Langmuir, Freundlich isotherms are subjected to adsorption data to estimate adsorption capacity. The results gained from this study were well described by the theoretical Langmuir and maximum adsorptive capacity of 33.33mg/g was obtained. The removal of Cr(VI) by Al-WTS was also investigated in a fixed bed column study. Experiments were conducted to study the effect of bed depth (10–30cm), flowrate (5– 15mL/min) and initial concentration (10-30mg/L). The column data was fitted by BDST, Thomas and Yoon-Nelson models. Adsorption capacity increases with increase in initial Cr(VI) concentration and bed depth. Thomas model well fits the experiment and gives high adsorptive capacity of 14.8mg/L. Al-WTS was used for the Cr(VI) removal from tannery wastewater in fixed bed column study and showed a high potential for the wastewater treatment.
URI: http://hdl.handle.net/123456789/11907
Appears in Collections:Enviromental Engineering

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