Evaluation of [222]Rn rate in medical dormitory of Kerman city

Radon [[222]Rn] Measurement in the residential environments is very important because of its effecting on human health and causing cancer in the respiratory system. [222]Rn is individually responsible for half of the natural radiation received in humans and influences on human by breathing. Hence, this study was undertaken to access the [222]Rn level in the dormitories of Kerman university of medical science [southeast of Iran] to ensure its safety level. In this study, for measuring [222]Rn level in seven dormitories of the Kerman University of Medical Sciences, the Lucas cell technique was used. This study was undertaken during the winter because of the high concentration of radon in this season due to closed building ambience. In this study, the highest measured radon gas rate was 24.5 Bq/m[3] in Boustan [1]. Average concentrations of the radon gas in all dormitories were 4.7 Bq/m[3], which is lower than the standard level. The results of this study showed that the [222]Rn level in all dormitories was lower than the normal amount [48 Bq/m3] as well as the standard level

[Application of dry activated sludge for lead and cadmium adsorption: isotherm and kinetic modeling]

Heavy metals have an important role on organism life and their high concentration may be a great threat for humans and other organisms' lives. Up to now, various methods have been used for the removal of these metals, which include the adsorption process. The aim of this study was the recovery of municipal disposals, and using as absorbent for lead and cadmium removal from aqueous solutions. Adsorption of lead and cadmium on dry activated sludge was investigated. Activated sludge was obtained from diary industry [Tehran]. All experiments were performed in batch system on 202 synthetic samples to investigate the effects of pH, contact time initial concentration lead and cadmium and adsorbent dose. The most conventional adsorption and kinetic models were applied to describe metal adsorption and dynamic reaction. The results showed that with increasing of adsorbent doses, contact time and pH solution, lead and cadmium removal efficiency increased. The maximum lead and cadmium adsorption was obtained at pH: 6 and an equivalent time of 180 min. With increasing initial concentration of lead and cadmium, removal efficiency decreased. The obtained results in this study were matched with langmuir 2 isotherm [R[2]>0.99] and interparticle diffusion kinetic [R[2]>0.94]. Maximum adsorption capacity of lead and cadmium on dry activated sludge was obtained to be 2.66 and 1.66mg/g, respectively. Maximum constant rate of lead and cadmium was 0.045 and 0.041mg/g.min[0.5], respectively. According to the results, dry activated sludge is recommended as a low cost and available adsorbent to remove lead and cadmium from aqueous solutions

Survey efficiency of electrocoagulation on nitrate removal from aqueous solution

Water supply for consumption is one of the crucial objectives of water supply systems. Using of excessive fertilizer is a main source of nitrate content in water. The high amounts of nitrate in water have a determinable effect on the environment which must be removed due to drinking and industrial water standards. The purpose of this study is nitrate removal from aqueous solution by Electrocoagulation process. The applied pilot was comprised of a reservoir, electrode and power supply. In this study pH, electrical potential difference, nitrate initial concentration, total dissolved solid, kind of electrode, electrode connection methods and number of electrode were studied. Moreover, obtained optimum conditions were tested on Kerman water. The results showed that the electrocoagulation process can reach nitrate to less than standard limit. pH, electrical potential difference, total dissolved solids and number of electrodes have direct effect and initial concentration of nitrate has reverse effect on nitrate removal. This study also showed that under optimum condition, nitrate removal from Kerman water distribution system was 89.7%. According to the results, Electrocoagulation process is suggested as an effective technique in nitrate removal

Efficiency of calcium and magnesium removal by nanofiltration membrane from synthetic water under different operating conditions

There are various techniques for reduction or removal of hardness of water each with its own special advantages and disadvantages. Nanofiltration, process due to its simplicity and efficiently, has gained a great attention and is used for removal of various ions and organic matters. The aim of this study was to investigate the evaluation of efficiency of calcium and magnesium removal by a nanofiltration membrane from synthetic water under different operating conditions. This study was performed in laboratory scale using a commercial NF membrane similar to pilot scale. NF experiments were conducted using a calcium initial concentrations [280, 300, 320, 340 and 360 mg/L] and magnesium initial concentrations [60, 80, 100, 120 and 140 mg/L] with flow rate of 0.4 L/min [Qi] and 0.8 L/min [Q[2]]. To investigate the removal of calcium and magnesium as a function of co-existing anions and cations for NF membrane, sodium, potassium, calcium and magnesium ions [as cation] and chloride, nitrate and sulfate ions [as anion] were chosen. The results revealed that with the increase in initial calcium and magnesium concentration, the removal efficiency decreased, with increasing initial calcium concentration from 280 mg/L to 360 mg/L, the removal efficiency decreased from 69.08% to 61.25%, respectively and magnesium removal efficiency declined from 70.05% to 62.25% with increasing concentration from 60 mg/L to 140 mg/L, respectively. In addition, while flow rate varied from 0.4 L/min to 0.8 L/min, calcium and magnesium removal efficiency descended to approximately 5%. Most effectiveness due to anions and cations with calcium and magnesium were related to sulfate and divalent cations and chloride and sodium lowest effectiveness related to choride anion and sodium cation respectively. According to the results, nanofiltration process was applied as efficient and proper method for hardness [calcium and magnesium] removal from water

Color removal from water by coagulation/caustic soda and lime

Due to aesthetic aspects, use of colored water even approved hygienically, is not acceptable worldwide. Consumers prefer to use colorless water. Color in water is usually associated with aromatic compounds produced from decay of natural herbal substances. Undesirable taste and odor and disinfection by products are of the reasons of color existence in water. The present study was performed using jar apparatus, lime and NaOH as softener agent and for increasing the pH of the process. Alum and ferric chloride coagulants were used to increase the size of flocs in various pH and color removal from water. It was tried to simulate the conditions of water treatment plants. Coagulant and lime doses, initial color and pH were studied. After the process, the residual color, as well as pH and electrical conductivity of water were measured. The results showed a significant increase in color removal with increasing pH. The highest percentage of color removal was 75% using 40mg/L of alum and ferric. The best efficiency of color removal was 86.68% and 94% by 12[g/L] lime for methylene blue and eriochrome black T, respectively. However, during the procedure, the electrical conductivity of water increased