ABSTRACT
Introduction: Arsenic contamination of surface and groundwater has been categorizd among high profile environmental problems around the world. The matter is of most concern where unsafe water is used for drinking. Sahand region reservoir in northwest of Iran supplies water for drinking, industrial and agricultural purposes through irrigation of 11000 hectares of lands
Materials and Methods: The hydrochemistry status of Sahand dam basin and arsenic plume distribution in water recourse was evaluated by analyzing 308 water samples from surface and ground water according to the standard methods. In addition, geological features information of basin were obtained based on recent site studies and field investigations
Results: Elevated concentrations of arsenic [range = 0-1440 ppb, mean = 171.68 ppb] were detected in water basin and dam. According to the delineating evidences, regional geological background and volcanic activities can be considered as the main sources of the natural genesis of arsenic in the study area
Conclusion: Notable amounts of arsenic sulfide were recorded in seams, gaps, fractures of limestone, marl, sandstone and an overlying ferruginous conglomerate. Concentrations of arsenic varied seasonally highlighting the maximum concentration observed in autumn and early winter [December]. Seasonal fluctuations can be probably attributed to changes in geochemical conditions in sediments at the bottom of reservoir
Subject(s)
Water , Groundwater , Hydrology , Volcanic EruptionsABSTRACT
Background: Nitrate is an acute and well-known hazardous contaminant, and its contamination of water sources has been a growing concern worldwide in recent years. This study evaluated the feasibility of nitrate removal from water using the traditional coagulants alum and ferric chloride with lower concentrations than those used in the conventional coagulation process
Methods: In this research, two coagulants, alum and ferric chloride, were compared for their efficiency in removing nitrate in a conventional water treatment system. The removal process was done in a batch system [jar test] to examine the effects of coagulant dosages and determine the conditions required to achieve optimum results
Results: The results revealed that ferric chloride at an initial dose rate of 4 mg/L reduced nitrate concentration from 70 mg/L to less than the World Health Organization [WHO] guideline value [50 mg/L N-NO[3]]. However, the removal efficiency of alum was not salient to significant nitrate reduction
Conclusion: In conclusion, ferric chloride was more effective than alumin removing NO[3], even in common dosage range, and can be considered a cost-effective and worthy treatment option to remediate nitrate-polluted water. Furthermore, the removal of nitrate by coagulation can be simple and more economical than other treatment alternatives