ارزیابی عملکرد فرایند انعقاد برای حذف مقادیر کم کدورت و رنگ آب با استفاده از منعقدکننده‌های مختلف

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشیار مرکز تحقیقات سلامت، دانشگاه علوم پزشکی کرمانشاه

2 استادیار گروه شیمی کاربردی، دانشکده شیمی دانشگاه رازی- کرمانشاه

3 دانش‌آموخته کارشناسی ارشد مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی کرمانشاه

چکیده

پژوهش حاضر در مقیاس آزمایشگاهی و با استفاده از دستگاه جارتست انجام شد. به‌منظور مقایسه کارایی چهار منعقدکننده معدنی (پلی آلومینیم کلراید، سولفات فرو، کلرورفریک و سولفات آلومینیم) در حذف کدورت و رنگ آب، سه متغیر مستقل مطالعه شد. محدوده مورد مطالعه برای کدورت (NTU 10،20،50) ، رنگ (TCU 5 و 10) و غلظت ماده منعقد کننده (30،25،20،15،10،5 میلی‌گرم در لیتر) انتخاب شد. مراحل اختلاط سریع و کند به‌ترتیب با شدت 80 و 30 دور در دقیقه برای مدت یک و 20 دقیقه انجام شد و سپس نمونه‌ها به‌مدت 30 دقیقه به‌منظور ته‌نشینی در شرایط سکون قرار گرفتند. چهار پارامتر شامل کدورت، هدایت الکتریکی، pH و رنگ به‌عنوان پاسخ فرایند سنجش شدند. ویژگی ته‌نشینی لخته‌ها پس از مشاهده، با واژه‌های ضعیف، نسبتأ خوب، خوب و عالی توصیف گردید. نتایج حاصل نشان داد که پلی‌آلومینیم‌کلراید با غلظت 5 میلی‌گرم در لیتر بهترین منعقدکننده برای حذف کدورت 99/8 تا 99 درصد و رنگ 100 درصد است. با این وصف با افزایش مقدار این منعقدکننده، اندازه لخته در کدورتهای NTU50 و 20، 10 همچنان ریز بوده ولی سرعت ته‌نشینی آن خیلی خوب است. با افزایش غلظت منعقد کننده‌ها، میزان هدایت الکتریکی افزایش و قلیاییت کاهش یافت. همچنین بیشترین و کمترین افزایش میزان هدایت الکتریکی و TDS به‌ترتیب در منعقدکننده کلرور فریک و پلی‌آلومینیم‌کلراید حاصل شد.

کلیدواژه‌ها


عنوان مقاله [English]

Performance Evaluation of Coagulation Process in Removal of Low Turbidity and Color from Water Using Different Inorganic Coagulants

نویسندگان [English]

  • Meghdad Pirsaheb 1
  • Ali Akbar Zinatizadeh 2
  • Abdollah Dargahi 3
1 Assoc. Prof. of Health Research Center, Kermanshah University of Medical Sciences, Kermanshah
2 Assist. Prof. of Chemistry, Faculty of Sciences, Razi University, Kermanshah
3 Former Grad. Student of Environmental Health, Faculty of Public Health, Kermanshah University of Medical Science, Kermanshah
چکیده [English]

This research work was carried out in lab scale using a Jar-test set up. In order to compare the performance of four inorganic coagulants (poly aluminum chloride, ferro sulfate, ferric chloride, aluminum sulfate) in removal of turbidity and color from water, three independent variables (turbidity, color and coagulants dosage) were investigated. The region of exploration for the process was taken as the area enclosed by turbidity (10, 20, 50 NTU), color (5, 10 TCU) and concentration of coagulants (5, 10, 15, 120, 25, 30 mg/l) boundaries. The rapid and slow mixing steps were provided by the rate of 80 rpm for 1 min and 30 rpm for 20 min, respectively. The samples were then remained for 30 min as settling stage. Four parameters including turbidity, electrical conductivity (EC), pH and color were measured from the samples supernatant. Settling characteristics of the flocs formed were descriptively reported as poor, fair, good and excellent. From the results, poly aluminum chloride with concentration of 5 mg/l was found to be the best for the removal of turbidity (99-99.8 %) and color (100 %). However, fine flocs with very good settling velocity was observed at the condition with initial turbidity of 10, 20, 50 NTU. Increase in EC along with decrease in alkalinity was obtained as the coagulants concentrations were increased. The maximum and minimum amount of increase in EC and TDS were resulted from ferric chloride and poly aluminum chloride, respectively.

کلیدواژه‌ها [English]

  • Coagulant
  • Turbidity
  • Electrical conductivity
  • Alkalinity
  • Color
Pari Zanganeh, A.H., Ghadimi, Y., and Abedini, Y.A. (2004) Water pollution and the main scurces of pollutants of Abhar river in Zanjan province Proc. 6th National Congress on Environmental Health, Mazandaran University of Medical Sciences, Sari , 441-449
Graham, N.J.D. (1986) Ortho kinetic flocculation rapid filtration J. of Water Research (54), 715-724
UNESCO, WHO and UNEP (2000) Water quality assessments Chapman and Hall Ltd., Landon (25)
HDR Engineering Inc (2001) Handbook of public water system John Wiley and Sons, New York.
WHO. (1991) Guidelines for drinking water quality New Dehli, Vol 2
McGhee, T. (1991) Water supply and sewerage McGraw- Hill, Washington, D.C.
Montgomery, J.M. (1995) Water treatment principals and design John Wiley and Sons, New York
Lipoor, V., and Bazerafshan, A. (2003) Water treatment 1st Ed., Vol1, Daneshnema, Tehran
Shamansouri, M., and Neshat, A.A. (2004) Comparison of poly aluminum chloride, aluminum sulfate and ferric chloride in order to TOC & MPN removal in optimum concentrations for turbidity removal from raw water of Esfahan water treatment plant Proc. 6th National Congress on Environmental Health, Mazandaran University of Medical Sciences, Sari , 441-449
Kennth D.K. (2008) Water treatment plant operation Beard Pub., California
Letterman, R.D., and Peron, R.W. (1990) Contaminants in polyelectrolyte's used in water treatment J. AWWA (82), 87-97
Weber, W.J. (1972) Physiochemical process for water quality control John Wiley and Sons, New York
Shi, B., Li, G., Wang, D., Feng, C., and Tang, H. (2007) Removal of direct dyes by coagulation: The performance of preformed polymeric aluminum species J. Hazard. Mater (143), 567-574
Wang, D., Sun, W., Xu, Y., Tang, H., and Gregory, J. (2004) Speciation stability of inorganic polymer flocculant-PACl Colloids Surf. A: Physicochem. Eng. Aspects (243), 1-10
Jiang, J. Q. (2001) Development of coagulation theory and prepolymerized coagulants for water treatment Separation and Purification Methods (30), 127-142
Ye, C., Wang, D., Shi, B., Yu, J., Qu, J., Edwards, M., and Tang, H. (2007) Alkalinity effect of coagulation with polyaluminum chlorides: Role of electrostatic patch Colloids Surf. A: Physicochem. Eng. Aspects (294), 163-173
Omelia, C.R., and Shin, J.Y. (2001) Removal of particle using dual media filtration modeling and experimental studies J. Water Supply, IWA 4 (1), 73-79
Eric, H., and Kara, H. (2002) Optimizing coagulant conditions for the worcester water filtration plants A Major Qualifying Project Report Submitted to the Faculty of Worcester Polytechnic Institute, USA
Malhutra, S. (1994) Polyaluminum chloride as an alternative coagulant Proc. 20th WEDC Conference Colombo, Sri Lanka , 289-291
Tang, H.X., and Luan, Z.K. (1995) Features and mechanism for coagulation flocculation process of polyalumimum chloride J. Environ. Sci. 2 (7), 204-211
Luan, Z.K. (1997) Theory and application of inorganic polymer flocculant-polyaluminium chloride Doctorial Dissertation, Research Center for Eco-Enviromental Sciences, Chinese Academy of Sciences, Beijing.
Liu, W., Huang, H., and Peng, J. (2001) Application of polyaluminium chloride in Shenzhen water supply Qingyouan Water Purification Water Supply Group Ltd., Schenzhen, China
Mahvi, A.H., and Ahmadi Moghaddam, M. (2003) Technical, economical and healthy evaluation of PACL application in water treatment Iranian J. of Public Health (32), 6-8
Banihashemi, A., Alavi Moghaddam, M. R., Maknoon, R., and Nikazar, M. (2008) Lab-scale study of water turbidity removal using aluminum inorganic polymer J. of Water and Wastewater (66), 82-86
Abdolah Zadeh, M., Torabian, A., and Hassani, A.H. (2009) Comparison of the performance of poly chloride(PACI), ferric chloride(FeCl3), in turbidity and organic matter removal; from water source, case- study; Karag river, in Tehran water treatment plant no.2 J. of Water and Wastewater (70), 23-31
Tchobanoglous, G., and Schroeder, E.D. (1985) Water quality: Characteristics, modeling and modification, Addison Wesley Pub. Co., Reading, MD.
USEPA. (1970) National secondary drinking water regulation Federal Register 153 (44), 42195-42202