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Experimental Analysis of Greenhouse Wastewater Treatment Processes using Photocatalysts Versus UV Treatment to Decrease Energy Consumption and Increase Contaminant Removal

Zarei, Mohammad Hossein | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58690 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Roshandel, Ramin; Ghasemi, Shahnaz; Sadeh, Mojtaba
  7. Abstract:
  8. With the increasing use of greenhouse cultivation systems, particularly hydroponic systems due to their higher yield per unit area, and on the other hand, considering the ongoing water resource limitations, the necessity of recycling existing resources has become more prominent. The effluent from these greenhouses contains considerable amounts of nutrients beneficial for plants, which, upon complete removal of microbial contamination, can be reused in the production cycle, reducing water and nutrient consumption. In this study, two microbial load treatment methods were evaluated: photocatalytic treatment under visible light simulating sunlight, and treatment using UV-C irradiation. For the photocatalytic treatment, titanium dioxide (TiO₂), TiO₂ doped with 0.5, 2, 5, 10, and 20 wt% iron, as well as TiO₂ doped simultaneously with 10 wt% iron and 0.2, 1, and 5 wt% silver, were employed. The photocatalysts were synthesized via the sol-gel method. Eventually, a sample with 10% iron and 5% silver was selected as the final optimal photocatalyst, exhibiting excitation and light absorption up to 460 nm. This photocatalyst, at a concentration of 150 ppm, was able to remove approximately 99.85% of Escherichia coli at 1 McFarland dilution within 2 hours and 20 minutes, reaching 100% removal at 200 ppm. Furthermore, the use of UV-C lamp irradiation with 20 W resulted in approximately a 5-log reduction, whereas a UV-C lamp with 8 W led to about a 1.6-log reduction in microbial load. Finally, the hydroponic greenhouse effluent was treated using both methods, and other important parameters of the effluent, including pH, EC, and nitrate, were measured before and after treatment, indicating that the Hotocatalytic method had negligible effect on these parameters. From an energy perspective, although the UV method consumed less energy for a given microbial load reduction, the photocatalytic method, despite higher energy consumption, offers the potential to utilize natural sunlight as a clean and renewable energy source
  9. Keywords:
  10. Photocatalyst ; Sol-Gel Method ; Hydroponic Greenhouse ; Ultraviolet Treatment ; Greenhouse Cultivation ; Photocatalytic Purification

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