Document Details
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Document Type |
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Thesis |
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Document Title |
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ENHANCEMENT OF THE BIOLOGICAL TREATMENT OF DAIRY WASTEWATER BY COMBINING PHOTOCATALYSIS AND AEROBIC DIGESTION تحسين كفاءة المعالجة البيولوجية لمياه صرف منتجات الألبان باستخدام تقنيتي الأكسدة الحفزوضوئية والهضم الهوائي |
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Subject |
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Faculty of Meteorology, Environment and Arid Land Agriculture |
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Document Language |
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Arabic |
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Abstract |
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The demand of the dairy product increasing day by day. Therefore, dairy processing industries using a large volume of water for milk process. Generally, a single liter of processed milk produces four liters of water as effluent. Discharged effluents contain a large amounts of suspended solids, organic materials, salts, oils, and fats depends on the milk processing unit. The high contents of oil, grease, and fats in dairy wastewater hinder the biological treatment process. Thus, a pretreatment of dairy wastewater is needed before biological aerobic treatment.
Among various treatment methods, photocatalysis has shown efficient competence for non-selective degradation of organic contaminants. Photocatalysis has the edge over other traditional technologies as it does not require complex reaction material for production of free radicals, therefore, it is comparatively economical. Further more, non-toxic secondary pollutants are usually produced thus, photocatalysis provides an environmentally sound technology for organic contaminant removal from wastewater. Where use of visible light photocatalysis provides additional benefits by efficient free radicals production and dependency on freely available solar light.
In the present study, three novel visible light active photocatalyst composites (CuO-GO/TiO2, S-rGO/ZnS, and Ni(OH)2/GO/TiO2) were successfully fabricated and analyzed for their various characteristics using different tools such as X-ray differaction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, photoluminescence (PL) spectroscopy and Fourier-transform infrared spectroscopy (FTIR) etc. Thereafter, the materials were tested for multiple environmental applicationss, i.e. degradation of organic pollutants to analyze the photocatalytic activity of the material using the 2-chlorophenol (2-CP) as a model pollutant, microbial pollutant and Pretreatment of dairy wastewater to improve the aerobic digestion process. Results obtained revealed that the composite material (CuO-GO/TiO2) showed improved 2-CP degradation, as 86% removal was achieved. In the case of Ni(OH)2/GO/TiO₂ nano-composite, photocatalytic actively removed 80 % of the 2-CP from synthetic wastewater solution under visible light. The third composite material (S-rGO/ZnS) own superior photocatalytic activity with 99.3 % degradation of 2-CP within four hours of solar light exposure. Overall, the optimum operating conditions were achieved for pH range 5.0-6.0, duration 210-240 min, and pollutant concentration of 25-50 mg/l, for all composite materials. The use of composite catalysts Ni(OH)2/TiO2/GO and S-rGO/ZnS also revealed the efficient removal of microbial pollutants. The Ni(OH)2/TiO2/GO composite showed bacterial count as low as 350 ± 50×108 cfu/ml where in case of S-rGO/ZnS plate count was only 0.6 x 106 cfu/ml.
The photocatalystic for pretreatment of dairy wastewater increases the solubilization of the organic matters up to 24% (CuO-GO/TiO2), 45.4% (Ni(OH)2/GO/TiO₂) and 113% (S-rGO/ZnS). An increase in soluble chemical oxygen demand (sCOD) was recorded with the photocatalytic preteratmemt which is significantly higher than photolysis (without catalyst) pretreatment. Subsequently, This improved the aerobic digestibility of dairy wastewater where total chemical oxygen demand (tCOD) was significantly lowered to 134.8 mg/L (CuO-GO/TiO2), 54 mg/L (Ni(OH)2/GO/TiO₂) and 71 mg/L (S-rGO/ZnS) during 30-40 days of the aerobic digestion process. Overall, the present study revealed that the visible light active composite material could be used as an efficient catalyst for the removal of toxic organic pollutants, microbes, and treatment of dairy effluent. Thus, it can be applied in wastewater treatment plants with a dependency of extensively available visible light. |
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Supervisor |
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Dr. Mohammed Hassan Abdullah |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1441 AH
2019 AD |
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Added Date |
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Wednesday, December 18, 2019 |
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Researchers
| زياد عمر العفيف | Alafif, Ziad Omar | Researcher | Doctorate | |
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