بررسي كاربرد زائدات معدني صنايع سنگ در حذف نيترات از محلول هاي آبي

چكيده انگليسي :

Evaluation of Wastes from Building Stone Production Industries for Nitrate Removal from Aqueous Solution SeyedMohammad Mirmohammadsadeghi moh 1379@yahoo com Date of Submission 06 04 2011 Department of Civil and Environmental Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Majid Sartaj msartaj@yahoo com Abstract Surface and groundwater resources as the two main resources of drinking water should possess certain characteristics in terms of quality This makes water treatment as one of the most environmental concerns Nitrate is the most stable form of nitrogen and high concentrations of nitrate in water resources is considered as a water pollution source Nitrate is present in water resources as a result of biochemical decomposition of organic and inorganic compounds which is discharged directly or indirectly into surface and ground waters High concentrations of nitrate can cause a disease called methemoglobinemia Available treatment methods for nitrate removal are classified into biological physical and chemical methods The information presented above emphasizes the importance of achieving appropriate and optimum ways for nitrate removal in water resources At present adsorption process is one of the most viable methods due to low sludge production ease of waste disposal and economic considerations The main purpose of this study was to evaluate adsorption process efficiency and various types of waste residues from building production industries as a source of adsorbent material for nitrate present in aqueous mediums Application of waste residues of construction materials as a low cost product of quarry industry can easily replace other high cost methods for nitrate removal In this study five types of adsorbents were selected for preliminary experiments which included dolomite lime white travertine red travertine and slag Based on the results from the first stage dolomite and red travertine were selected for subsequent stages Different factors are affecting adsorption process In this research initial nitrate concentration 10 50 mg l initial pH 3 9 and adsorbent dosage 4 10 mg l were the three significant factors whose effect on adsorption process were investigated By optimizing the process nitrate concentration reduced to the standard levels below 10 mg L Samples with predetermined initial nitrate concentrations 10 20 50 mg L were made from a stock synthetic solution by dilution Initial pH was adjusted in neutral level pH 7 and 8 g L of dolomite and red travertine were added to each sample Samples were mixed on the shaker with a mixing rate of 200 rpm and 150 rpm for dolomite and red travertine respectively For kinetics studies samples at 5 10 20 30 45 60 90 120 180 240 300 minutes were collected and analyzed Equilibrium time was determined to be about 120 minutes for travertine and 180 minutes for dolomite In adsorption kinetic models quasi first order model didn t match the data but quasi second order model with a correlation coefficient of 0 99 described the results well Analysis of variance showed that three mentioned factors had considerable effect on nitrate removal Dosage had the biggest impact on adsorption 40 59 of response for travertine and 51 6 for dolomite The maximum nitrate removal achieved were 82 7 and 84 7 for travertine and dolomite respectively for an initial concentration of 50 mg L adsorbent dosage of 8 g L and initial pH 3 Isotherm adsorption tests were carried out in batch reactor in concentrations of 10 20 50 mg l and different dosages of absorbent and in identical pH level to reach the

ميرمحمدصادقي، محمد

بررسي كاربرد زائدات معدني صنايع سنگ در حذف نيترات از محلول هاي آبي

فرايند جذب , تراورتن قرمز , دولوميت , مدل هاي ايزوترم