بررسی عوامل مؤثر بر پدیده بالکینگ در سیستم تصفیه هوازی لجن فعال در پساب کارخانه پتروشیمی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد، گروه مهندسی شیمی، واحد ماهشهر، دانشگاه آزاد اسلامی، ماهشهر، ایران

2 استادیار، گروه مهندسی شیمی، واحد ماهشهر، دانشگاه آزاد اسلامی، ماهشهر، ایران

چکیده

بدون شک فرایند لجن فعال یکی از متداول‌ترین روش‌های تصفیه بیولوژیکی فاضلاب است. از جمله شایع‌ترین مشکلات سیستم‌های فرایند لجن فعال، حجیم شدن لجن (بالکینگ) است، که بیش از 50 درصد تصفیه‌خانه‌های فاضلاب به روش لجن فعال در سراسر جهان دائما و یا گهگاه با این مشکل مواجه هستند. در این حالت چگالی نسبی لخته‌ها کم بوده، باعث ته‌نشینی نامناسب در حوضچه‌های ثانویه می‌شود و باعث مشکلاتی مانند کاهش بازده تصفیه، تحمیل هزینه‌های اضافی در تصفیه و دفع لجن مازاد فعال می‌شود. در این پژوهش که در مقیاس آزمایشگاهی (پایلوت) در واحد تصفیه‌خانه شرکت پتروشیمی شهید تندگویان انجام شد، به بررسی عوامل مؤثر بر ایجاد بالکینگ، که شامل پارامترهای فرایندی مانند تنظیم نسبت خوراک ورودی به میکروارگانیسم، غلظت میکروارگانیسم، تأمین میزان مواد مغذی نیتروژن و فسفر، اکسیژن محلول، دما، pH و کمک منعقدکننده پلی‌الکترولیت کاتیونی برای بهبود میزان ته‌نشینی لجن فعال پرداخته شد. پارامترهای بهینه در میزان ته‌نشینی به‌ترتیب F/M برابر با ۳۵/۰، MLSS در محدوده ۲۵۰۰ تا ppm ۳۰۰۰، مواد مغذی نیتروژن و فسفر نسبت به میزان آلودگی (COD/N/P) در محدوده۱/۴/۱۰۰ تا ۱/۵/۱۰۰، DO از ۲ تا mg/L ۳، دمای ۲۵ تا ۳۵ درجه سلسیوس، pH معادل 5/8 و در میزان دوز TSS/L، mg/gr 8/4 از کمک ماده منعقدکننده پلی‌الکترولیتی در مدت زمان ۱۸۰ دقیقه بود. به‌طورکلی می‌توان نتیجه گرفت که با تنظیم پارامترهای فرایندی در محدوده اشاره شده می‌توان میزان SVI را در محدوده مطلوب نزدیک بهmg/L ۱۵۰ کنترل کرد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigating the Factors Affecting the Bulking Phenomenon in the Activated Sludge Aerobic Treatment System in the Petrochemical Plant Effluent

نویسندگان [English]

  • Masoud Vafadari 1
  • Somayeh Tourani 2
1 MSc. Student, Department of Chemical Engineering, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
2 Assist. Prof., Department of Chemical Engineering, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
چکیده [English]

Undoubtedly, the activated sludge process is one of the most common methods of biological wastewater treatment. Among the most common problems of activated sludge process systems is bulking of sludge (bulking). More than 50% of activated sludge wastewater treatment plants worldwide constantly or occasionally face this problem. In this case, the relative density of the flocs is low. It causes inappropriate sedimentation in secondary ponds and causes problems such as reducing treatment efficiency and imposing additional costs in the treatment and disposal of excess activated sludge. The current study, which was carried out on a laboratory scale (pilot) in the refinery unit of Shahid Tondgoyan Petrochemical Company, to investigate the factors affecting the creation of bulking. Factors include process parameters such as adjusting the ratio of input feed to microorganism (F/M), microorganism concentration, supply of nitrogen and phosphorus nutrients, dissolved oxygen, temperature, pH, and the use of cationic polyelectrolyte coagulant to improve the sedimentation rate of activated sludge. The optimal parameters in the amount of sedimentation are F/M equal to 0.35, MLSS in the range of ppm 2500 to 3000 ppm, nitrogen, and phosphorus nutrients relative to the amount of pollution (COD/N/P) in the range of 100/4/1 until 100/5/1, dissolved oxygen 2 to 3 mg/L, temperature 25-35 °C, pH range 8.5 and in the dose of 4.8 mg/gr TSS/L of cationic polyelectrolyte coagulant in 180 min. In general, by adjusting the process parameters in the indicated range, the amount of SVI can be controlled in the desired range of close to 150 mg/L.

کلیدواژه‌ها [English]

  • Activated Sludge
  • Bulking
  • SVI
  • Microorganism Concentration

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مجله آب و فاضلاب
دوره 34، شماره 3 - شماره پیاپی 146
مرداد و شهریور 1402
صفحه 89-103

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