بررسی استفاده مجدد از لجن برگشتی واحد زلال‌ساز برای بهبود کارایی فرایند انعقاد و لخته‌سازی در تصفیه‌خانه آب

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکترای آلودگی محیط‌زیست، گروه علوم و مهندسی محیط‌زیست، واحد لاهیجان، دانشگاه آزاد اسلامی، لاهیجان، ایران

2 دانشیار، گروه علوم و مهندسی محیط‌زیست، واحد لاهیجان، دانشگاه آزاد اسلامی، لاهیجان، ایران

3 استادیار، گروه علوم و مهندسی محیط‌زیست، واحد لاهیجان، دانشگاه آزاد اسلامی، لاهیجان، ایران

چکیده

استفاده از مواد منعقدکننده و کمک منعقدکننده، به‌طور معمول برای حذف و ته‌نشینی بهینه کدورت و رنگ به‌کار برده می‌شود و حاصل آن تولید لجن رقیق حاوی مواد منعقدکننده، کمک منعقدکننده و بسیاری از مواد شیمیایی است که می‌توان بخشی از این لجن را به واحد انعقاد تصفیه‌خانه‌های آب برگشت داده و تا اندازه‌ای از مصرف بیشتر مواد منعقدکننده و پلی‌الکترولیت جلوگیری کرد. با شناسایی ساختار لجن و تأثیر آن بر روی پارامترهایی مانند کدورت و رنگ می‌توان مقدار استفاده از مواد منعقدکننده و کمک منعقدکننده را بهینه کرد. در این پژوهش پارامترهای جامدات کل، جامدات ثابت و جامدات فرار برای لجن برگشتی واحد انعقاد تصفیه‌خانه آب اندازه‌گیری شد و تأثیر آن بر مقدار استفاده شده از کلروفریک، پلی‌الکترولیت و میزان کاهش کدورت و رنگ بررسی شد. برای هر یک از پارامترهای تعیین شده تعداد 30 مورد نمونه‌برداری از آب ورودی، آب خروجی و لجن برگشتی انجام شد. TS، FS و VS در بیشترین مقدار به‌ترتیب 4/8، 2/96 و 4/15 درصد و در این حالت میزان مصرف کلروفریک و پلی‌الکترولیت کمترین مقدار مصرف معادل 3 و  mg/L03/0 بود. برای جامدات لجن برگشتی در بالاترین مقدار خود بیشترین مقدار کدورت و رنگ آب ورودی NTU 55 و TCU19 اندازه‌گیری شد. بر اساس آزمون هم‌بستگی اسپیرمن افزایش TS، FS و VS میزان مصرف کلروفریک و پلی‌الکترولیت را کاهش می‌دهد. همچنین با افزایش جامدات لجن برگشتی میزان حذف کدورت و رنگ افزایش می‌یابد (05/0P<).

کلیدواژه‌ها

عنوان مقاله [English]

Investigating the Reuse of the Return Sludge of the Clarifier unit to Improve the Efficiency of the Coagulation and Flocculation Process in the Water Treatment Plant

نویسندگان [English]

  • Farhad Panahi 1
  • Hasan Karimzadegan 2
  • Fatemeh Shariati 2
  • Abdolkarim Keshavarz 3
1 PhD. Student of Environmental Pollution, Dept. of Environmental Sciences and Engineering, Lahijan Campus, Islamic Azad University, Lahijan, Iran
2 Assoc. Prof., Dept. of Environmental Sciences and Engineering, Lahijan Campus, Islamic Azad University, Lahijan, Iran
3 Assist. Prof., Dept. of Environmental Sciences and Engineering, Lahijan Campus, Islamic Azad University, Lahijan, Iran
چکیده [English]

To optimize the use of coagulants and coagulant aids, it is important to understand the structure of the sludge and its effect on parameters such as turbidity and color. In this study, the levels of total solids, fixed solids, and volatile solids were measured in the return sludge from a water treatment plants coagulation unit. The impact of these parameters on the consumption of ferric chloride and polyelectrolyte, as well as on the reduction of turbidity and color, was investigated. Thirty samples were taken from the inlet water, outlet water, and return sludge to measure each parameter. The highest levels of TS, FS and VS were found to be 8.4%, 96.2%, and 15.4%, respectively. In this case, the consumption of ferric chloride and polyelectrolyte was lowest, at 3 and 0.03 mg/L, respectively. The highest levels of turbidity and color in the return sludge were found to come from the inlet water, at 55 NTU and 19 TCU, respectively. The Kolmogorov-Smirnov test showed that an increase in TS, FS and VS in the return sludge reduced the consumption of ferric chloride and polyelectrolyte by p < 0.05. Additionally, an increase in return sludge solids led to a higher removal rate of turbidity and color, with a confidence level of p < 0.05. Overall, this study highlights the importance of understanding the structure of chemical sludge and its impact on the effectiveness of coagulants and coagulant aids in water treatment plants. By optimizing the use of these chemicals, water treatment plants can operate more efficiently and effectively, resulting in cleaner and safer drinking water for communities.

کلیدواژه‌ها [English]

  • Coagulants
  • Coagulant Aids
  • Sludge
  • Returned Sludge
  • Sludge Disposal

مراجع

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مجله آب و فاضلاب
دوره 34، شماره 4 - شماره پیاپی 147
مهر و آبان 1402
صفحه 63-79

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