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Optimization of the Pulp and Paper Mill Wastewater Treatment System from Recycling with the Aim of Reducing COD by Conducting a Laboratory Pilot Plant

Yousefi, Farid | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55591 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Raie, Mohammad
  7. Abstract:
  8. Paper and cardboard waste pulping consume large volumes of water, so the discharge of this effluent without proper treatment can have far-reaching environmental consequences. The color and variable COD concentration of wastewater in this industry make treating this wastewater complicated. Therefore, this study aims to reduce the COD of the wastewater treatment plant of a pulp and paper mill under different laboratory conditions to achieve environmental standards in Iran.In this study, coagulation-flocculation and the Fenton process on the wastewater entering the treatment plant were investigated first. It was found that coagulation and flocculation by 750-1250 ppm of alum coagulant and ten ppm cationic polymer is the most suitable option due to proper reduction of COD and turbidity as well as generation of less sludge. In the second step, biological treatment was investigated by two dual systems, SBR-SBR and SBMBBR-SMBBR, in aerobic mode. The single SBR system in an anaerobic-aerobic way was investigated in the other reactor. The results showed that the primary reactors require a retention time of about 10 hours and 45 minutes, and for the secondary reactors, 4 hours and 30 minutes are sufficient. The SBMBBR reactor was selected as the most suitable option in the biological section. The primary SBMBBR system can remove COD in the range of %86 ±2, which efficiency may be reduced by 2 to 3% by applying organic load shocks. The COD can be removed by %89 ±2 using a secondary reactor and reach 300 ppm. In the tertiary treatment, according to the COD output from the biological reactor, coagulation-flocculation was used first, and it was concluded that if the COD value is about 250 mg/l, the coagulation and flocculation process by alum can reduce the COD value below 200 mg/l. If the COD value is around 400mg/l, advanced oxidation should be used after coagulation and flocculation. At this stage, the results showed that in the case of using UV/H2O2, in addition to the ability to remove non-biodegradable COD, there is also the ability to remove color and turbidity from the effluent. In this process, the best result occurs at pH five, and the amount of H2O2 and the appropriate intensity of UV radiation are obtained according to the initial COD
  9. Keywords:
  10. Advanced Oxidation Process ; Coagulation ; Flocculation ; Fenton Method ; Waste Paper ; Chemical Oxygen Demand (COD)Removal Ratio ; Sequence Batch Moving Bed Biofilm Reactor (SBMBBR) ; Sequencing Batch Reactor (SBR)

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