Iranian Journal of Health and Environment
سلامت و محیط زیست
ijhe
Medical Sciences
http://ijhe.tums.ac.ir
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2008-2029
2008-3718
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jalali
1397
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2018
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پیش تصفیه لجنهای بیولوژیکی فاضلاب شهری با امواج اولتراسونیک: بررسی کارایی در بهبود فرایندهای هیدرولیز، تثبیت و آبگیری
Pretreatment of municipal biological sludge by ultrasonic process: efficiency in hydrolysis, stabilization, and dewatering
فاضلاب
wastewater
كاربردي
Applicable
<div style="text-align: justify;"><strong><span style="font-family:b lotus;"><span style="font-size:12.0pt;">زمینه و هدف:</span></span></strong><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> تجزیه لجن با امواج اولتراسونیک، بهعنوان یک روش پیش تصفیه قبل از فرایند تثبیت و آبگیری است که باعث تغییر در ویژگیهای فیزیکی و شیمیایی آنها میشود. هدف اصلی از این تحقیق بررسی کارایی امواج اولتراسونیک در بهبود فرایندهای هیدرولیز، تثبیت و آبگیری لجن فعال خام فاضلاب شهری است. </span></span><br>
<strong><span style="font-family:b lotus;"><span style="font-size:12.0pt;">روش بررسی:</span></span></strong><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> از لجن فعال برگشتی به حوض هوادهی، نمونهبرداری انجام گردید و آمایش فیزیکی با هدایت امواج اولتراسونیک با فرکانسهای 20 و </span></span><span dir="LTR"><span style="font-family:times new roman,serif;"> kHz</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">40 در زمانهای</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">0/5،</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">1،</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">3، 5، 10، 15،</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">30 و</span></span><span dir="LTR"><span style="font-family:times new roman,serif;"> min </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">60</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">انجام گرفت. در ادامه بهبود فرایندهای هیدرولیز، تثبیت و آبگیری نمونهها با انجام آزمایشاتی نظیر:</span></span><span dir="LTR"><span style="font-family:times new roman,serif;">TS </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">،</span></span><span dir="LTR"><span style="font-family:times new roman,serif;">TSS </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">، </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">CST</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">، </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">SRF</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">، </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">VS</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">، </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">nVS</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">، </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">VSss</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">و </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">VS<sub>SOL</sub></span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> مورد بررسی قرار گرفت. </span></span><br>
<strong><span style="font-family:b lotus;"><span style="font-size:12.0pt;">یافتهها</span></span></strong>: <span dir="LTR"><span style="font-family:times new roman,serif;">VS <sub>SOL</sub></span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> درفرکانس </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">kHz</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 20 در زمان</span></span> <span dir="LTR"><span style="font-family:times new roman,serif;">min </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">15 به میزان 73 درصد افزایش</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">داشت و </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">VS <sub>SOL</sub></span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> در فرکانس </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">kHz</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 40 در زمان </span></span><span dir="LTR"><span style="font-family:times new roman,serif;"> min</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">10 به میزان 100 درصد</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">افزایش داشت. درصد کاهش </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">VS</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> در فرکانس</span></span><span dir="LTR"><span style="font-family:times new roman,serif;"> kHz </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">20 از زمان </span></span><span dir="LTR"><span style="font-family:times new roman,serif;"> min</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">15 شروع و در</span></span> <span dir="LTR"><span style="font-family:times new roman,serif;">min </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">60 به 18 درصد رسید. کاهش این شاخص در فرکانس </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">kHz</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 40 در زمان </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">min</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 10 شروع و تا</span></span><span dir="LTR"><span style="font-family:times new roman,serif;">min </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 60 به میزان 24 درصد</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">رسید. مقاومت ویژه لجن در دو فرکانس 20 و</span></span><span dir="LTR"><span style="font-family:times new roman,serif;"> kHz </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">40 در</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">زمان تماس </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">min</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 1 به ترتیب 25 و 20 درصد کاهش داشت و زمان مکش موئینه در دو فرکانس 20 و </span></span> <span dir="LTR"><span style="font-family:times new roman,serif;">kHz</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">40</span></span> <span style="font-family:b lotus;"><span style="font-size:12.0pt;">در زمان تماس </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">min</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 1 به ترتیب کاهش 28 و 21 درصد را نشان داد.</span></span><br>
<strong><span style="font-family:b lotus;"><span style="font-size:12.0pt;">نتیجهگیری:</span></span></strong><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> بهترین کارایی هیدرولیز جامدات آلی لجن خام بیولوژیکی در زمان </span></span><span dir="LTR"><span style="font-family:times new roman,serif;"> min</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">10 با فرکانس </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">kHz</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 40</span></span> <span dir="RTL"><span style="font-family:b lotus;"><span style="font-size:12.0pt;">بهدست</span></span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> آمد. بیشترین راندمان تثبیت لجن در فرکانس</span></span> <span dir="LTR"><span style="font-family:times new roman,serif;">kHz </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">40 در زمان</span></span> <span dir="LTR"><span style="font-family:times new roman,serif;">min </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">60 بدست آمد. بهترین شرایط آبگیری لجن در فرکانس</span></span><span dir="LTR"><span style="font-family:times new roman,serif;"> kHz </span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;">20 در زمان تماس </span></span><span dir="LTR"><span style="font-family:times new roman,serif;">min</span></span><span style="font-family:b lotus;"><span style="font-size:12.0pt;"> 1 حاصل گردید. </span></span></div>
<div style="text-align: justify;"><strong>Background and Objective</strong>: Ultrasonic disintegration is a pretreatment process before stabilization and dewatering that degrades sludge and changes its physical and chemical characteristics. The aim of this study was to investigate the effectiveness of ultrasonic in enhancing hydrolyses, stabilization and dewatering of municipal raw activated sludge<strong>.</strong><br>
<strong>Materials and Methods:</strong> The samples were taken from returned activated sludge and then they were exposed to ultrasonic (Frequency: 20 and 40 kHz) in different times (0.5, 1, 3, 5, 10, 15, 30, and 60 min). The effectiveness of ultrasonic for hydrolysis, stabilization and dewatering processes were determined with measuring TS, TSS, CST, SRF, VS, nVS, VSss, and VSsol.<br>
<strong>Results</strong>: VSsol was increased by 73% in 15 min and at frequency of 20 kHz, whereas VSsol increas was100% at 10 min and 40 kHz. The reduction of VS was observed at 15 min and 20 kHz. Then after, it was reached 18% after 60 min. For 40 kHz, VS reduction started at 10 min and reached 24% after 60 min. Specific resistance of sludge at two frequencies of 20 and 40 kHz and contact time of 1 min were decreased by 25 and 20% respectively. The capillary suction time at the frequencies of 20 and 40 kHz and contact time of 1 min was decreased 28 and 21%, respectively.<br>
<strong>Conclusion</strong>: The optimum effectiveness of ultrasonic in hydrolysis of organic matter of raw biological sludge was at the contact time of 10 min and frequency of 40 kHz. The highest stabilization at the frequency of 40 kHz was observed at 60 min contact time. The best condition for sludge dewatering was at frequency of 20 kHz and contact time of 1 min.<br>
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فاضلاب شهری, لجن, تصفیه لجن, اولتراسونیک, آبگیری
Municipal wastewater, Sludge, Sludge treatment, Ultrasonic, Dewatering
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36
http://ijhe.tums.ac.ir/browse.php?a_code=A-10-1378-1&slc_lang=fa&sid=1
R
Barati Rashvanlou
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براتی رشوانلو
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