کاربرد روش سطح پاسخ در تحلیل پارامترهای اثرگذار بر حذف کدورت و نماتدها در فرآیند فیلتراسیون مستقیم

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه عمران، دانشکده مهندسی، دانشگاه فردوسی مشهد، مشهد، ایران

2 گروه زیست شناسی، دانشکده علوم، دانشگاه فردوسی مشهد، مشهد، ایران

چکیده

نماتدها به دلیل مقاومت در برابر گندزدایی و قابلیت بلعیدن و انتقال پاتوژن‌ها به شبکه‌های آبرسانی شناخته شده هستند. فرآیندهای انعقاد و فیلتراسیون نقش مهمی را در راستای حذف این ارگانیسم‌ها در تصفیه‌خانه‌های آب ایفا می‌نمایند. بررسی تأثیر پارامترهای مختلف بر حذف نماتدها، همواره مورد توجه پژوهشگران بوده است. اما بررسی همزمان اثرات این پارامترها نیازمند تحلیل‌های آماری مناسب است. در این پژوهش با استفاده از روش سطح پاسخ و طراحی مرکب مرکزی وجهی، تأثیر همزمان غلظت کلرور فریک )به‌عنوان ماده منعقد کننده(، نوع بستر فیلتر و نرخ فیلتراسیون بر کارایی حذف کدورت و نماتدها در فرآیند فیلتراسیون مستقیم بررسی شد. بر اساس نتایج حاصله، متوسط راندمان حذف کدورت، نماتدهای متحرک و نماتدهای غیر متحرک در فیلتر تک لایه به ترتیب 96/14 ،94/02 و 41/39 درصد و در فیلتر دولایه به ترتیب 96/61 ،95/76 و 46/01 درصد بود. با افزایش غلظت کلرور فریک، راندمان حذف نماتدها به مقدار قابل توجهی بهبود یافت. افزایش نرخ فیلتراسیون سبب کاهش کارایی حذف نماتدهای غیر متحرک شد. اما افزایش این متغیر، افزایش غیرمنتظره راندمان حذف نماتدهای متحرک را به دنبال داشت. بروز این رفتار متمایز از نماتدها، موجب استقلال و عدم وابستگی راندمان حذف کل نماتدها )مجموع نماتدهای متحرک و غیر متحرک( به نرخ فیلتراسیون گردید. بر اساس نتایج، به کارگیری فیلتراسیون مستقیم برای شرایطی که کدورت ورودی به تصفیه‌خانه کمتر از NTU 5 باشد، توصیه می‌گردد. البته این روش تصفیه بایستی با گندزدایی اولیه همراه گردد تا نماتدهای متحرک را به حالت غیر متحرک درآورده و ضعف فیلترها را در حذف این نماتدها پوشش دهد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Application of response surface methodology in the analysis of parameters influencing the removal of turbidity and nematodes in direct filtration process

نویسندگان [English]

  • Javad Abdollahi 1
  • Shahnaz Danesh 1
  • Masoumeh Bahreini 2
  • Nima Emrani 1
1 Civil Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
2 Biology Department, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
چکیده [English]

Nematodes are well-known due to their resistance to disinfectants and their ability to ingest and carry pathogens to water distribution systems. Coagulation and filtration play significant roles in removing these organisms in water treatment plants. Investigating the effect of different parameters on the nematodes removal has always been an interest to researchers. However, the simultaneous evaluation of these parameters needs a comprehensive statistical analysis. In this study, the effects of ferric chloride dosage, filter media type, and filtration rate were investigated on the removal efficiency of turbidity and nematodes in direct filtration process using response surface methodology and central composite face-centered design. Based on the results, the average removal efficiency of turbidity, motile nematodes and non-motile nematodes in single-media filter were 96.14, 94.02 and 41.39%, respectively. Meanwhile, these numbers for dual-media filter were obtained as 96.61, 95.76 and 46.01%, respectively. With the increase in coagulant dosage, the removal efficiency of nematodes was improved significantly. Furthermore, the removal efficiency of non-motile nematodes was increased as the filtration rate decreased. However, an increase in the filtration rate led to an unexpected increase in the removal efficiency of motile nematodes. This distinct behavior of the nematodes led to the independence of total nematodes removal from the filtration rate. According to the results, using the direct filtration process is suggested, when the turbidity of raw water is lower than 5 NTU. However, primary disinfection must be applied to immobilize the nematodes and compensate the weakness of granular beds in the removal of motile nematodes.

کلیدواژه‌ها [English]

  • Surface water treatment
  • direct filtration
  • Nematode, turbidity
  • Response surface methodology
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