بررسی تأثیر شدت و روند اختلاط، بر کارایی فرایند انعقاد و لخته‌سازی و ارتقاء پساب تصفیه‌خانه SBR فاضلاب شهر یزد

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشجوی دکترای مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی و خدمات بهداشتی درمانی شهید صدوقی یزد، یزد، ایران

2 استاد گروه مهندسی بهداشت محیط، دانشگاه علوم پزشکی شهید صدوقی یزد، یزد، ایران

3 دانشیار گروه مهندسی بهداشت محیط، مرکز تحقیقات علوم و فناوری محیط زیست، دانشگاه، علوم پزشکی شهید صدوقی یزد، یزد، ایران

4 دانشجوی دکترای مهندسی بهداشت محیط ، دانشکده بهداشت، دانشگاه علوم پزشکی و خدمات بهداشتی درمانی شهید صدوقی یزد، یزد، ایران

5 مدیر تصفیه‌خانه‌های آب و فاضلاب، شرکت آب و فاضلاب یزد

چکیده

ارتقاء کیفیت پساب‌های خروجی از تصفیه‌خانه‌های فاضلاب به روش انعقاد و لخته‌سازی می‌تواند روشی مناسب برای بهبود کیفیت پساب و دستیابی به استانداردهای بالاتر برای استفاده مجدد باشد. در این تحقیق با استفاده از ماده منعقد کننده PAC، تأثیر شدت اختلاط در مرحله اختلاط تند و کند و مقایسه سرعت اختلاط ثابت با سرعت کاهشی، در مرحله لخته‌سازی برای بهبود کارایی فرایند انعقاد و لخته‌سازی در تصفیه پیشرفته پساب خروجی از تصفیه‌خانه SBR یزد مورد بررسی قرار گرفت. به این منظور، از دستگاه جارتست به‌عنوان یک سیستم پایلوت منقطع استفاده شد. نتایج این تحقیق نشان داد از میان سه سرعت همزن برای اختلاط تند (rpm200 و 150 و 100)، راندمان حذف کدورت،BOD ، COD و TSS در سرعت اختلاط تند rpm150 بیشتر از سایر سرعت‌ها بود. مقایسه سرعت‌های ثابت همزن در مرحله اختلاط دور کند rpm 40، 30 و 20 با سرعت اختلاط کاهشی دور کند (rpm 10 تا rpm40) نشان داد راندمان حذف کدورت، BOD، COD و TSS در حالت سرعت اختلاط کاهشی بالاتر از هر سه حالت سرعت ثابت دور کند است. کمترین حجم لجن تولیدی در میان حالت‌های سرعت ثابت اختلاط کند، مقدار 34 میلی‌لیتر بر لیتر و مربوط به سرعت اختلاط rpm 30 بود. مادامی که از لخته‌سازی کاهشی استفاده شد، وضعیت تولید لجن بهبود یافته و میزان این پارامتر به اعداد 26 میلی‌لیتر بر لیتر تغییر یافت.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effects of Intensity and Mixing Speed on the Efficiency of Coagulation and Flocculation Processes and Improving Effluent Quality from Yazd SBR Wastewater Treatment Plant

نویسندگان [English]

  • Ali Nikoonahad 1
  • Mohammadhassan Ehrampoush 2
  • mohamadtaghi ghaneian 3
  • abdolmajid gholizadeh 4
  • Saidvahid Ghelmani 5
1 PhD Student, Department of Environmental Health Engineering, School of Health, Shahid Sadoughi University of Medical sciences, Yazd, Iran
2 Prof., Department of Environmental Health Engineering, School of Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
3 Assoc. Prof., Environmental Science and Technology Research Center, Department of Environmental Health Engineering, School of Health, Shahid Sadoughi University of Medical sciences, Yazd, Iran
4 PhD Student, Department of Environmental Health Engineering, School of Health, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
5 Yazd Water and Wastewater Engineering CO., Yazd, Iran
چکیده [English]

Coagulation and flocculation techniques are appropriate methods for improving the quality of efflunets from wastewater treatment plants that help achieve higher standards of water reuse. In this study, PAC was used as the coagulant in the SBR treatment system of Yazd Wastewater Treatment Plant and the effects of mixing intensity during rapid and slow mixing steps were investigated on the improved efficiency of coagulation and flocculation processes. Meanwhile, constant and declining mixing speeds during the flocculation step were compared. For the purposes of this study, the Jar test unit was employed as a batch reactor. Results showed that from among the three mixer speeds of 100, 150, and 200 rpm in the rapid mixing tank, the 150 rpm mixing speed yielded higher removal efficiencies for turbidity, BOD, COD, and TSS. In addition, comparison of the constant speeds (20, 30, and 40 rpm) and the declining speeds (40 to 10 rpm) in the slow mixing stage showed that the declining speed yielded higher turbidity, BOD, COD, and TSS removal efficiencies than each of the three fixed speeds. Moreover, the lowest volume of sludge produced was 34 ml/L at a slow mixing speed of 30 rpm from among the constant speeds used in the slow mixing tank. Finally, it was found that the declining speed flocculation led to an improved sludge production of 26 mg/L.

کلیدواژه‌ها [English]

  • Coagulation
  • flocculation
  • Decreasing Mixing Speed
  • Enhanced Treatment Plant
  • Yazd
Aghapour, A. & Mohammadi, A., 2011, "Investigating the coagulation efficiency of paci in reduction of water turibidty in Shahrchay river in city of Orumieh and its health effects", Health System Research, 6(4), 762-769.

Aguilar, M. I., Saez, Liornes, M., Soler, A. & Ortuno, I.F., 2003, "Microscopic observation of particle reduction in slaughterhouse wastewater by coagulation–flocculation using ferric sulphate as coagulant and different coagulant aids", Water Research, 37(9), 2233-2241.

Ayguna, A. & Yilmazb, T., 2010, "Improvement of coagulation-flocculation process for treatment of detergent wastewaters using coagulant aids", International Journal of Chemical and Environmental Engineering, 1(2), 97-101.

Aziz, H.A., Alias, S., Adlan, M, N., Asaari, A.H. & Zahari, Sh., 2007, "Colour removal from landfill leachate by coagulation and flocculation processes", Bioresource Technology, 98(1), 218-220.

Chon, K., Kim, S.J., Moon, J. & Cho, J., 2012, "Combined coagulation-disk filtration process as a pretreatment of ultrafiltration and reverse osmosis membrane for wastewater reclamation: An autopsy study of a pilot plant", Water Research, 46(6), 1803-1816.

Gao, B.-Y., Yue Q.-Y. & Wang, B.-J., 2003, "Electrophoretic nature and evaluation of poly-aluminum-chloride-sulfate (PACS) as a coagulant for water and wastewater treatment", Journal of Environmental Science and Health, 38(5), 897-907.

Guida, M., Mattei, M., Della Rocca, C., Melluso, G. & Meric, S., 2007, "Optimization of alum-coagulation/flocculation for COD and TSS removal from five municipal wastewater", Desalination, 211(1), 113-127.

Ismail, I.M., Fawzy, A.S., Abdel-Monem, N.M.,  Mahmoud, M.H. & El-Halvang, M.A., 2012, "Combined coagulation flocculation pre treatment unit for municipal wastewater", Journal of Advanced Research, 3(4), 331-336.

Kord Mostafapoor, F., Bazafshan, E. & Kamani, H., 2008, "Effectiveness of three coagulants of polyaluminum Chloride, Aluminum sulfate and ferric chloride in turbidity removal from drinking water", Physician East, 10(2), 87-95. (In Persian)

López-Maldonado, E., Oropeza- Guzan, M.T., Jurado-Baizavai, J.L. & Ochoa-Teran, A., 2014, "Coagulation–flocculation mechanisms in wastewater treatment plants through zeta potential measurements", Journal of Hazardous Materials, 279, 1-10.

Matilainen, A., Vepsäläinen, M. & Sillanpää, M., 2010, "Natural organic matter removal by coagulation during drinking water treatment: A review", Advances in Colloid and Interface Science, 159(2), 189-197.

Ozkan, A. & Yekeler, M., 2004, "Coagulation and flocculation characteristics of celestite with different inorganic salts and polymers", Chemical Engineering and Processing: Process Intensification, 43(7), 873-879.

Ramphal, S. & Sibiya, M., 2014, "Optimization of coagulation-flocculation parameters using a photometric dispersion analyser", Drinking Water Engineering and Science, 7(2), 73-82.

Stechemesser, H. & Dobiáš, B., 2005, Coagulation and flocculation, Taylor and Francis, Boca Raton, USA.

Tchobanglous, G., Stensel, H.D. & Burton, F., 2014, Wastewater engineering: Treatment and resource recovery, 5th Ed., Metcalf and Eddy Inc., New York.

Üstün, G.E., Akal Solmaz, S.K., Ciner, F. & Baskaya, H.S., 2011, "Tertiary treatment of a secondary effluent by the coupling of coagulation–flocculation–disinfection for irrigation reuse", Desalination, 277(1), 207-212.

Väänänen, J., 2014, Applying coagulation, flocculation and discfiltration in tertiary treatment, Lund University Pub., Lund, Sweden.