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Tăng nồng độ của asen (As) cùng với sắt (Fe) thường xảy ra trong vùng nước mặt đất trong vùng đồng bằng lũ lụt Tây Bengal (Ấn Độ) và Bangladesh. Trong thực tế có thể được loại bỏ khi Fe được thêm vào như là chất kết tủa sau khi quá trình oxy hóa (III) As (V) và hấp phụ As (V) vào hydroxit Fe. Đơn vị loại bỏ sắt ở Bangladesh (Iru) đã được cài đặt để loại bỏ một cách tự nhiên xảy ra Fe cung cấp Fe-nước cho người dân. Do đó điều tra đã được tiến. | Natural Arsenic in Groundwater Occurrence Remediation and Management -Bundschuh Bhattacharya and Chandrasekharam eds 2005 Taylor Francis Group London ISBN 04 1536 700 X Optimisation of iron removal units to include arsenic removal A.K. Sharma J.C. Tjell H. Mosbffik Environment Resources Technical University of Denmark DTU Lyngby Denmark ABSTRACT Elevated concentrations of arsenic As along with iron Fe often occur in the ground waters in flood plains of West Bengal India and Bangladesh. In practice As can be removed when Fe is added as coagulant after oxidation of As III to As V and adsorbing As V onto Fe hydroxides. In Bangladesh iron removal units IRU were installed to remove naturally occurring Fe to supply Fe-free water to villagers. Hence investigations were carried out to examine the efficiency of IRU for As removal and to study whether similar As removals can be obtained by simple sedimentation in buckets compared to the IRU. The results show that IRUs have removal rates for As comparable to simple sedimentation. It was observed that Fe As molar ratios above 80 were necessary to achieve residual As concentrations below 50 g L. Based on the extensive data available on As and naturally occurring Fe concentrations in wells removal of As may be attained at a quarter of the tube wells exceeding an As concentration of 50 g L. The results further showed that due to improper construction of the IRUs untreated water was mixed with treated water and hence resulted in poorer Fe and As removals. It is concluded that removal of As by naturally occurring Fe in IRUs in the areas with elevated Fe concentrations is functioning and can be employed as an As removal method but further research is needed to improve the construction of the IRUs with a possibility of introducing a simple As III oxidation unit and to improve the Fe removal capacity of the IRU and thereby increase the As removal efficiency. 1 INTRODUCTION Presence of iron Fe in the ground waters of Bangladesh is .
