ارزیابی اثرات پدیده لایهبندی حرارتی بر کیفیت آب و راهکارهای کاهش انتشار آب سرد
محورهای موضوعی : شیمی و مهندسی شیمی کلیه گرایش هانسیم موسی خانی 1 , احمد اصل هاشمی 2 , غلامحسین صفری 3
1 - کمیته تحقیقات دانشجویی دانشگاه علوم پزشکی تبریز، تبریز، ایران
2 - گروه مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی تبریز، تبریز، ایران
3 - گروه مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی تبریز، تبریز، ایران. مرکز تحقیقات سلامت و محیطزیست، دانشگاه علوم پزشکی تبریز، تبریز، ایران
کلید واژه: لایهبندی حرارتی, کیفیت آب مخازن, انتشار آب سرد, شکوفایی سیانوباکتریها, برداشت انتخابی, ستونهای حبابدار, اختلاط دهندههای سطحی,
چکیده مقاله :
پدیده لایهبندی حرارتی یکی از چالشهای مهم در مدیریت مخازن سدها است که بهواسطهی تغییرات دمایی در ستون آب، منجر به تشکیل لایههای جداگانه با ویژگیهای فیزیکی و شیمیایی متفاوت میشود. این فرآیند نهتنها باعث کاهش شدید اکسیژن محلول در لایههای عمیقتر آب میگردد، بلکه منجر به بروز مشکلاتی همچون انتشار آب سرد از مخازن سدها در پاییندست، افزایش غلظت فلزات سنگین نظیر آهن و منگنز، و شکوفایی سیانوباکتریها میشود. این مقاله به صورت یک مطالعه مروری نظاممند طراحی شده است که با هدف جمعآوری، تحلیل و ارزیابی جامع فناوریها و روشهای موجود برای کاهش انتشار آب سرد از سد ناشی از لایهبندی در مخازن آب انجام شده است. جستجوی منابع علمی از طریق پایگاههای داده معتبر شاملWeb of Science، Scopus، Google Scholar و پایگاههای تخصصی مهندسی آب و محیط زیست انجام شد. کلمات کلیدی مرتبط با موضوع، از جمله «لایه زدایی مخازن»، «انتشار آب سرد از سدها»، «ستونهای حبابی»، «اختلاط دهندههای سطحی»، «برداشت انتخابی چند سطحی» و «فناوری GELI» به زبانهای فارسی و انگلیسی به کار گرفته شدند. در این مقاله، ابتدا فرآیندهای طبیعی لایهبندی و لایهزدایی در مخازن بررسی شده است. سپس تأثیرات لایهبندی بر کیفیت آب از جنبههای مختلف، ازجمله کاهش اکسیژن محلول، انتشار آب سرد از سدها، افزایش فلزات سنگین، و رشد جلبکهای سمی مورد ارزیابی قرار گرفته است. در ادامه، سه راهکار فنی متداول برای کاهش اثرات لایهبندی و انتشار آب سرد از مخازن سد شامل: برداشت انتخابی با استفاده از سازههای برداشت چندسطحی، استفاده از ستونهای حبابدار، و بهرهگیری از اختلاطدهندههای سطحی معرفی و مقایسه شدهاند. نتایج این مطالعه نشان میدهد که انتخاب راهکار مناسب باید با توجه به ویژگیهای مخزن، اهداف مدیریتی، و هزینههای اجرایی صورت گیرد. لایهزدایی با ستونهای حبابدار، به دلیل توانایی در بهبود اکسیژن، کاهش فلزات و مهار رشد جلبکها، در اغلب موارد گزینهای مؤثر و کاربردی محسوب میشود.
Thermal stratification is one of the critical challenges in reservoir management, arising from temperature gradients in the water column that lead to the formation of distinct layers with varying physical and chemical properties. This phenomenon significantly reduces dissolved oxygen levels in deeper water layers and contributes to several environmental issues, including the release of cold water downstream, increased concentrations of heavy metals such as iron and manganese, and the proliferation of cyanobacterial blooms.
This article presents a systematic review aimed at collecting, analyzing, and comprehensively evaluating current technologies and methods for mitigating cold-water release from reservoirs caused by thermal stratification. A thorough literature search was conducted using reputable databases such as Web of Science, Scopus, Google Scholar, and specialized databases in water and environmental engineering. Relevant keywords—such as “reservoir destratification,” “cold-water release from dams,” “bubble columns,” “surface mixers,” “multi-level selective withdrawal,” and “GELI technology”—were used in both Persian and English. The study begins by reviewing natural processes of thermal stratification and destratification in reservoirs. It then assesses the impacts of stratification on water quality, including dissolved oxygen depletion, cold-water discharge, elevated heavy metal concentrations, and toxic algal growth. Subsequently, three common technical approaches for mitigating stratification and cold-water release are introduced and compared: selective withdrawal using multi-level intake structures, the use of bubble plume systems, and surface mixing devices. The findings suggest that the selection of an appropriate method depends on reservoir characteristics, management objectives, and implementation costs. Among the options, bubble plume systems are often considered an effective and practical solution due to their ability to enhance oxygenation, reduce metal concentrations, and suppress algal blooms.
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