اثر احداث تانک ذخیره‌سازی در سیستم متعارف لجن فعال بر کیفیت پساب خروجی و قابلیت ته‌نشینی لجن

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشیار گروه مهندسی بهداشت محیط و عضو مرکز تحقیقات فناوری‌های زیست محیطی دانشگاه علوم پزشکی جندی شاپور اهواز، اهواز، ایران

2 دانشجوی دکترای مهندسی محیط زیست، دانشگاه آزاد اسلامی واحد علوم و تحقیقات، تهران، ایران

3 استاد گروه مهندسی محیط زیست، دانشکده محیط زیست، دانشگاه تهران، تهران، ایران

چکیده

تصفیه و دفع لجن مازاد یک چالش بزرگ در تصفیه‌خانه‌های فاضلاب است. در این تحقیق کاهش حجم لجن در راکتور ناپیوسته متوالی در مقیاس پایلوت بررسی شد. دو راکتور ناپیوسته متوالی در مدت زمان ۱۲ ماه بهره‌برداری شد و پارامترهایی از قبیل COD، MLSS، pH، DO، SVI، SOUR، ORP در طول مدت بهره‌برداری راکتور مورد آزمایش قرار گرفت. نتایج نشان داد که در بین زمان‌های ماند سلولی مختلف (۵، ۱۰، ۱۵، ۲۰ ۲۵ روز) در زمان ماند ۱۰ روز بهترین راندمان حذف COD (۹۵ درصد) بدون مشکلات بالکینگ و همچنین تولید کف ایجاد شد. به‌منظور بررسی اثر متابولیسم جفت نشده فاز آنوکسیک و بی‌هوازی لجن بر کاهش تولید بیومس، لجن فاضلاب برای مدت ۱ تا ۴ ساعت قبل از فاز واکنش در راکتور با پتانسیل اکسیداسیون و احیای مختلف نگهداری شد. نگهداری لجن بعد از مدت چهار ساعت با پتانسیل اکسیداسیون و احیای 238- میلی‌ولت میزان COD را از ۶۰۰ به ۳۳ میلی‌گرم در لیتر کاهش داد و غلظت MLSS به‌طور جزئی از ۱۳۵۰ به ۱۵۰۰ میلی‌گرم در لیتر افزایش یافت. با استفاده از این مکانیسم، COD پساب خروجی پایین‌تر از استاندارد محیط‌ زیست از نظر دفع پساب به آب‌های پذیرنده و استفاده مجدد در کشاورزی است. از طرفی در پتانسیل اکسیداسیون و احیای برابر 238- میلی‌ولت، میزان  SOUR به mgO2/h.gVSS ۲۲ و میزانSVI به کمتراز ۴۰میلی‌لیتر بر گرم رسید.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effects of Sludge Holding Tank on the Effluent Quality and Sludge Settling Potential in Conventional Activated Sludge

نویسندگان [English]

  • Afshin Takdastan 1
  • Azadeh Eslami 2
  • Nasser Mehrdadi 3
1 Assoc. Prof. of Envivonmental Engineering, and Member of Environmental Technologies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
2 PhD Student of Environmental Engineering, Islamic Azad University of Sciences and Research, Tehran, Iran
3 Prof. of Environmental Engineering, Faculty of Environment, Tehran University, Tehran, Iran
چکیده [English]

Excess sludge treatment and disposal is a major challenge for wastewater treatment plants worldwide. In this study, sludge reduction was evaluated using pilot scale sequencing batch reactors (SBRs). Two SBRs were operated alongside each other over a period of 12 months during which time measurements were performed to determine COD, MLSS, MLVSS, pH, DO, SV1, SOUR, and ORP. The results showed that among the different SRT durations (5, 10, 15, 20, 25 days), the 10-day sludge retention time yielded maximum COD removal efficiency (90%) without any bulking or foaming problems. Prior to any reactions taking place in the reactor, the sludge was exposed to various oxidation reduction potentials for 1 to 8 hours in order to determine the effects of uncoupling metabolism on biomass production under different anoxic and anaerobic conditions. COD was observed to decrease from 600 to 33 mg/l while MLSS increased from 1350 to 1500 mg/l over a retention time of 7 hours and for an ORP value of -238 mv. The effluent COD obtained as a result of operating this process was below the limits set by environmental regulations for surface waters and reuse in agriculture. For an ORP value of -238mv, SOUR and SVI were measured to be 22 mgO2/h.gVSS and 40 ml/g, respectively.

کلیدواژه‌ها [English]

  • Activated sludge
  • Sludge Holding Tank
  • effluent quality
  • Excess Sludge Minimization

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