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http://hdl.handle.net/11375/23828
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DC Field | Value | Language |
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dc.contributor.advisor | Kim, Younggy | - |
dc.contributor.author | Jannati, Mahshid | - |
dc.date.accessioned | 2019-01-29T18:28:25Z | - |
dc.date.available | 2019-01-29T18:28:25Z | - |
dc.date.issued | 2019 | - |
dc.identifier.uri | http://hdl.handle.net/11375/23828 | - |
dc.description.abstract | Industrial wastewaters contain various contaminants depending on their sources, including phosphate, ammonium and heavy metals. To remove different contaminants, several physical, chemical or biological methods are applied in wastewater treatment plants. In this study, two contaminants of ionic lead and phosphate from two different wastewaters were considered separately with two different removal methods. Exoelectrogenic bacteria were studied for lead removal and application of zeolite for phosphate removal was also investigated. The examined methods were proposed for a relatively small-scale (maximum 5000 liters per day) and non-continuous treatment plant for achieving more than 90% removal of both contaminants. The first part of this project was investigating Pb(II) removal using a bio-electrochemical method. Lead, as a toxic and non-biodegradable heavy metal, has been a major concern in the wastewater treatment area. Microbial electrolysis cells (MECs) are known to remove heavy metals effectively while the exoelectrogenic bacteria oxidize organics at the anode electrode and cations (like heavy metals) get reduced at the cathode electrode. A study has shown that Pb(II) can be reduced both at the cathode and the bioanode. In this lab-scale study, exoelectrogenic bacteria have been prepared on the anode fibers of an MEC and then the enriched bioanode was used individually in the system without applying any voltages. The effectiveness of the proposed system on Pb(II) removal in different initial pH condition and the consistency of this system were studied. Pb(II) removal mechanisms were also investigated. Results showed more than 90% Pb(II) removal in 24 hours for a wide range of pH conditions (pH 5 to 9). Moreover, adding lead after each 24 hours for four times showed the high capacity of bioanode. Two mechanisms of direct reduction and biosorption were identified as the removal mechanisms of lead. Biosorption mechanism with the contribution of 82% to lead removal had a more significant role than the reduction mechanism. It was also indicated that the exoelectrogenic bacteria played the main role in both of the removal mechanisms by providing oxidation-reduction condition and biosorption capacity. The second aspect of this project was focused on phosphate removal using zeolite. Phosphate in wastewater and the resulting eutrophication have always been a crucial concern and have resulted in developing of different technologies for its removal. Natural zeolites with the capability of cation exchanging have been extensively studied for cation removal like ammonium. However, by pretreating zeolite and making changes on its physico-chemical properties, zeolite can also be used for removing anions like phosphate. In this aspect of the thesis, a clinoptilolite zeolite was pretreated by NaCl, Mg(OH)2 and Ca(OH)2 and the effect of pretreated zeolites on phosphate removal efficiency was investigated. Results showed no improvement with magnesium pretreatment although zeolite pretreated by sodium and calcium improved the removal efficiency. 18% phosphate removal by natural zeolite increased to 37% and 60% for zeolites pretreated by Ca(OH)2 and NaCl respectively. The existence of ammonium in the solution also increased the removal efficiency from 18% to 44% for natural zeolite and ammonium was removed itself by around 34%. Sodium and ammonium in the solution improved the removal efficiency due to being exchanged with calcium and increasing the calcium phosphate precipitation. Regarding that, the type of zeolite and its amount of calcium were shown to be effective on phosphate removal efficiency. In all conditions, phosphate was removed by calcium phosphate precipitants using either the calcium hydroxide added or the calcium in zeolite structure. Calcium-pretreated zeolite despite its high capacity for phosphate removal had a low efficiency which was explained by the mass transfer mechanism and shaking results showed that better shaking condition could improve mass transferring here and get to 100% phosphate removal by calcium-pretreated zeolite. However, using only calcium hydroxide without any zeolite could also remove 100% of phosphate. Using calcium hydroxide provided a high removal efficiency but increased the final pH as well. Pretreated zeolite had lower efficiency than calcium hydroxide but did not change the pH significantly and had the ability to remove ammonium as well. Using a type of zeolite with a high amount of calcium in its structure and existence of ammonium and sodium in solution along with an appropriate shaking condition can reach high removal efficiency as well. | en_US |
dc.language.iso | en | en_US |
dc.title | BIO-ELECTROCHEMICAL REMOVAL OF LEAD BY EXOELECTROGENS AND PHOSPHATE REMOVAL USING ZEOLITE FOR POTENTIAL INDUSTRIAL WASTEWATER TREATMENT | en_US |
dc.type | Thesis | en_US |
dc.contributor.department | Civil Engineering | en_US |
dc.description.degreetype | Thesis | en_US |
dc.description.degree | Master of Applied Science (MASc) | en_US |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Jannati_Mahshid_finalsubmission2019January_M.A.Sc..pdf | 1.39 MB | Adobe PDF | View/Open |
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