مسئله دفع بهینه لجن تصفیه‌خانه‌های آب، همچنین تغلیظ و آبگیری لجن تصفیه‌خانه‌های فاضلاب از موارد مهم مطرح در راستای اصول و اهداف توسعه پایدار به شمار می‌روند. در این تحقیق، امکان استفاده از لجن تصفیه‌خانه آب و کربن فعال با هدف جایگزینی یا کاهش مصرف پلی‌الکترولیت‌های کاتیونی در مرحله تغلیظ لجن تصفیه‌خانه‌های فاضلاب به روش لجن‌فعال در مقیاس پایلوت آزمایشگاهی بررسی گردید. برای این منظور، تاثیر مواد افزودنی مذکور به همراه پلی‌الکترولیت بر پارامترهای SVI، TTF، DS وpH درراستای بهینه‌سازی مرحله تغلیظ لجن فاضلاب مورد سنجش قرارگرفت. با افزودن mg/l 1پلی‌الکترولیت و 300 میلی‌گرم‌بر‌گرم جامدات خشک از لجن تغلیظ شده تصفیه‌خانه آب، بیشترین میزان کاهش SVI (80%) و افزایش DS (140%) بدست آمد. بیشترین میزان کاهش پارامتر TTF (82%) نیز در همین دوز با افزودن کربن فعال حاصل شد. مواد حالت دهنده تاثیر قابل‌توجهی بر مقدار pH لجن نداشتند. درنتیجه افزودن مواد حالت دهنده، تشکیل فلوک‌های منسجم با قطر بزرگتر، تغییر دانه‌بندی و افزایش تخلخل لجن مازاد بیولوژیکی حاصل شده و تغلیظ و جداسازی آب آزاد تسهیل می‌گردد. استفاده از این پسماندهای صنعتی، ضمن بهبود کارآمدی فرآیند تغلیظ لجن فاضلاب باعث کاهش 50 درصدی در مصرف پلی‌الکترولیت و جلوگیری از تاثیرات منفی ناشی از دفع این پسماندها در محیط‌زیست می‌گردد.
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