نوع مقاله : مقالات پژوهشی
نویسندگان
1 1- دانشجوی دکتری مهندسی عمران - محیط زیست، دانشکده مهندسی عمران، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران.
2 دانشیار گروه آموزشی مهندسی محیط زیست، دانشکده مهندسی عمران، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران
3 استاد، گروه مهندسی محیط زیست، دانشکده محیط زیست، دانشگاه تهران، تهران، ایران.
4 دانشیار، گروه طراحی فرایند، دانشکده مهندسی شیمی، دانشگاه صنعتی نوشیروانی بابل، بابل، ایران.
چکیده
مقدمه و هدف: امروزه، در بین مسائل مختلفی که بعنوان منابع آلوده‌کننده بشمار میروند، پلاستیک‌ها و مشتقات آن در جایگاه خاصی قرار دارد. بخش اعظمی از این پلاستیک‌ها در ابعاد میکرو و نانو میباشند. یکی از مهمترین منابع انتقال میکروپلاستیک‌ها، تصفیه خانه‌های فاضلاب هستند که مقدار زیادی از این ذرات که در فرایند تصفیه حذف نشده‌اند، وارد محیط‌های پذیرنده می‌شوند. هدف از این تحقیق، ابتدا تعیین روش بهینه شناسایی و استخراج ذرات از فاضلاب جهت شمارش و سپس بررسی میزان حذف در فرآیند تصفیه و همچنین مشخص کردن میزان ذرات خروجی از تصفیه خانه میباشد.
روش کار: نمونه‌گیری از ورودی و خروجی تصفیه‌خانه فاضلاب که در استان مازندران قرار دارد، بطور فصلی و در سه فصل بهار، تابستان و پاییز انجام گرفت تا مشخص گردد در چه فصلی از سال، میزان میکروپلاستیک‌های موجود در فاضلاب افزایش و یا کاهش می‌یابد. همچنین روش استخراج و شناسایی بر اساس عملیات اسیدشویی و بر پایه ایجاد اختلاف چگالی بوده که با بهینه‌سازی و نوآوری، نتیجه مطلوبی را به همراه داشته است.
یافته ها: با استفاده از این روش مقدار میکروذرات و میکروفیبرها به همراه اندازه و شکل ذره مشخص گردید و تعیین شد که فرآیند معمول تصفیه‌خانه تا چه حد قادر به جداسازی میکروپلاستیک‌ها از فاضلاب میباشد. فرآیند تصفیه‌خانه بطور میانگین میتواند 95 درصد از ذرات را جدا کند و این به این معناست که 5 درصد ذرات باقیمانده به همراه پساب خارج شده و وارد محیط‌های آبی میشود.
نتیجه‌‌گیری: در نهایت با توجه به تحقیق، مشخص گردید روش آزمایشگاهی تعیین شده، می تواند تا حد بسیار مطلوبی اقدام به شناسایی و استخراج میکروپلاستیک‌ها در اندازه های بسیار ریز نماید. همچنین تعیین پارامترهای مناسب حجم مایع، نمک مصرفی و استفاده از آهن دوظرفیتی افزایش راندمان را نسبت به روش‌های دیگر به همراه داشته و باعث شناسایی ذرات کوچکتری نسبت به تحقیقات گذشته گردید.
کلیدواژه‌ها
عنوان مقاله [English]
Investigation of the method of detection and separation of microplastics in wastewater treatment plants based on creating a density difference and determining the share of the treatment process in particle removal
نویسندگان [English]
- Gholam Reza Darvishi 1
- Majid Ehteshami 2
- Naser Mehrdadi 3
- Reza Abedini 4
1 Ph.D Candidate, Department of Environmental Engineering, Faculty of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran
2 Associate Professor, Department of Environmental Engineering, Faculty of Civil Engineering, Khajeh Nasir Toosi University of Technology, Tehran, Iran
3 Professor, Department of Environmental Engineering, Faculty of Environment, Water and Wastewater of Engineering, University of Tehran, Tehran, Iran
4 Associate Professor, Department of Process design, Faculty of chemical Engineering, Babol Noshirvani University of Technology, Babol, Iran
چکیده [English]
Today, plastics have a special place among the various issues that are considered as sources of pollution. Most of these plastics are in the dimensions of Micro and Nano. One of the most important sources of Microplastics transfer is wastewater treatment plants, where a large amount of these particles, which are not removed in the treatment process, enter the receiving environment. The purpose of this study is to first determine the optimal method of identifying and extracting particles from wastewater for counting and then to investigate the amount of removal and also to determine the amount of particles leaving the treatment plant.
Sampling of inlet and outlet of wastewater treatment plant located in Mazandaran province was done seasonally in three seasons of spring, summer and autumn to determine in which season of the year, the amount of microplastics in wastewater increases or decreases. Also, the extraction and identification method is based on acid washing operation and based on creating a density difference, which has resulted in a favorable result with optimization and innovation.
Using this method, the amount of Microparticles and microfibers along with the size and shape of the particle was determined and it was determined to what extent the normal treatment process is able to separate Microplastics from wastewater. The treatment plant can remove an average of 95% of the particles, which means that the remaining 5% of the particles are removed with the effluent and enter the aqueous environment.
Finally, it was found that the determined laboratory method can identify and extract Microplastics in very small sizes to a very desirable extent. Also, determining the appropriate parameters of liquid volume, salt consumption and the use of dual capacity iron increased the efficiency compared to other methods and led to the identification of smaller particles than previous research.
کلیدواژه‌ها [English]
- Microplastics
- wastewater treatment plant
- chemical reactions
- density difference
- separation
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