جستجوی مقالات مرتبط با کلیدواژه "water pollutants" در نشریات گروه "پزشکی"

Groundwater contamination has major effects on human health, industrial activity, agriculture, and the environment. The present study determined the concentration of lead, cadmium, arsenic, chromium, and nickel metals in the groundwater around the landfill in Juybar City and compared them with the drinking water standards.

In this descriptive-analytical study, 12 samples were sampled from four wells for three consecutive months. The concentration of heavy elements was measured using the graphite furnace atomic absorption technique (GFAA) based on standard water and wastewater methods. Also, the hardness, temperature, pH, and total dissolved solids (TDS) parameters were measured with portable devices.

Investigations showed that the average concentration of nickel, lead, chromium, and cadmium in well water was 0.0425, 0.0071, 0.0268, and 0.0117 mg/l, respectively. The average concentration of arsenic was not observed in any sample. The average temperature, hardness, pH, and TDS were measured in the range of 20-21°C, 108.66-136.33 mg/L, 7.3-7.36, and 566.25-712.33 mg/L. Also, the correlation coefficient showed a positive correlation between the metals nickel, chromium, lead, and cadmium and the parameters of temperature, hardness, pH, and TDS, as well as with each other at a confidence level of 0.01.

The amount of arsenic, lead, chromium, pH, and hardness are acceptable in the investigated wells for drinking purposes, but the amount of cadmium, nickel, and TDS is higher than the standard.

Organic matters enter to drinking water from a variety of sources, but one of the major sources of these compounds in aqueous solution can be decomposed plant and microbial residues. Chlorination is the most common method for water disinfection, the free chlorine in the water reacts with natural organic compounds and form disinfection byproducts. One of the dangerous byproducts is Trihalomethanes (THMs). These compounds are suspected to be carcinogenic for humans. In this study, 96 samples were taken from 4 points (Mianb Steghlal dam, output Minab water treatment plant, input and output of water treatment plant in Bandar Abbas) within 6 months. Parameters such as TOC, pH, temperature and chlorine residual were measured and used for prediction of THM formation by a methematical model. Results showed that Bandar Abbas drinking water has high TOC and THM formation potential is high. Minimum and maximum of THM was measured 14.78 and 84.86µg/l, respectively. Positive correlation was seen between concentrations of organic carbon and pH with THM formation. Increasing pH and TOC concentration in water, leads to increase of THM formation potential. Bandar Abbas drinking water has high potential to form THM, therefore, it is necessary to consider measures in this field.

The chemical quality of water used for dialysis fluid is a vital factor in the overall care received by dialysis patients. Therefore، water used for this purpose should be treated with advanced methods before use for dialysis. The objective of this study was to assess the efficiency of reverse osmosis systems to improve water quality used for dialysis fluid. In this descriptive study، 40 water samples were collected from inlet and outlet of reverse osmosis systems of 5 hemodialysis services of Isfahan hospitals، Iran، during April to August 2011. The samples were analyzed for physicochemical parameters including residual chlorine، chloramines، pH، hardness، Al، F، Cu، Mn، Cd، Cr، Pb، Ni concentration according to the standard methods for examining water and waste water. The results of this study showed that the reverse osmosis systems significantly reduce the amount of residual chlorine، chloramines، hardness، Na، K، F، NO3، SO4 and Mn، but it could not significantly reduce the amount of Cu، Zn، Cd، Cr، Pb and Al. However، the results also showed that the amount of NO3، hardness، Pb، Cd، Cr and Al in outlet samples of reverse osmosis systems was higher than the value given by association for the advancement of medical instrumentation (AAMI). Reverse osmosis systems could improve the quality of water used for hemodialysis but they do not reduce the level of some contaminant to the recommended values for dialysis fluid. This condition may be unsafe for hemodialysis patients. Therefore، a rigorous control of chemical contaminants is necessary in order to ensure that hemodialysis therapy is in a good quality.

Background and Çadmium is one of the toxic elements which contaminate water resources through industrial, domestic, agricultural effluents and un hygienic burdening of industrial and urban waste materials. Studies shows that surface and subsurface waters in some areas near to the pollutant sources are contaminated with cadmium 0.1 to 1.0 mg/l. No study has been done about omiting the low concentrations of cadmium (poresent in the contaminated resources) with the help of activated carbon, determination of isotherms and the influencing factors on it. The aim of this study was to determine cadmium absorption isotherm on activated granular carbon GÂÇ, and also determine the effect of temperature and water pH on absorption isotherms. Ând finally determine the rate of efficacy of using activated carbon column in omition of cadmium from water. Çertain weights of activated carbon (0.05-0.07 gram) were added seperately to 250 ml of water with certain concentration of cadmium present in flask and pH was adjested, the flasks were kept in refrigerated incubater equiped with shaker, temperature was edjusted. Ïn order to determine the time equilibrium of abserption, the flasks were shaked with duration of 30 minutes to 6 hours in incubator. Ât each time interval the concentration remained cadmium in solution after fillration of the samples were measured according to the standard by atomic absorption mwthod. With the help of data concerning experiments on determination of isotherms, synthetic of cadmium absorption on sctivated carbon, the effect of activated carbon on the speed of absorption, effect of initial cadmium concetration on coefficient of absorption. Âs well as the effect of temperature changes and pH on isotherms was determined. The rate of cadmium absorption on activated carbon column at work conditions, was comared with the expected rate on isotherm. Break through curves related to cadmium containing water for concontration of D.26 mg/L. for at the of ËBÇT for 30 minuts and for the Çoncentration of 0.59 mg/Li for at two contact time of 30 and 60 minuts were plotted. The rate of cadmium absorption on activted carbon increased with increasing in pH and temperature. Though by increasing initial concentration of cadmium the rate of its absorption on Ünit Weight of autivated carbon(9) increased. But removing efficiency Çertain amount of activated Çaobon declined. Çadmium absorption on activated Çarbon Fllew the first order of kinetic. By increasing the rate of cutivated Çarbon, absorption of Çadmium increased. For Çoncentration of of Çadmium, the break through offer passing water was 55 folds more on bed volume and for Çocentration of 0.59 mg/Lifor after Passing was 40 fold of volume accured The rate of Çadmium uptake on Çolumn of Gac was more than the expected rate of isotherm. Çonclusion: Though Çomplate removal of 0.26 mg/Lifor and 0.59 mg/Lifer of Çadmium of water through activated Çarbon column is possible. But the break through in the plot related to the performance of the Çolumn is partially happens soon.