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There is a global need to develop low-cost technologies to remove arsenic from water for individual household water supply. In this study, a purified and enriched waste material (treated magnetite waste, TMW) from the Trai Cau's iron ore mine in the Thai Nguyen Province in Vietnam was examined for its capacity to remove arsenic. The treatment system was packed with TMW that consisted of 75% of ferrous-ferric oxide (Fe(3)O(4)) and had a large surface area of 89.7 m(2)/g. The experiments were conducted at a filtration rate of 0.05 m/h to treat groundwater with an arsenic concentration of 380 microg/L and iron, manganese and phosphate concentrations of 2.07 mg/L, 0.093 mg/L and 1.6 mg/L respectively. The batch experimental results show that this new material was able to absorb up to 0.74 mg arsenic/g. The results also indicated that the treatment system removed more than 90% arsenic giving an effluent with an arsenic concentration of less than 30 microg/L while achieving a removal efficiency of about 80% for Mn(2 + ) and PO(4) (3-). This could be a promising and cost-effective new material for capturing arsenic as well as other metals from groundwater.

In this study, different processes such as flocculation with ferric chloride (FeCl3) and deep bed filtration (sand filtration and dual media filtration) as a pre-treatment were used for seawater desalination. The performance of these pre-treatments was determined in terms of silt density index (SDI) and modified fouling index by using microfilter (MF-MFI), ultrafilter (UF-MFI), and nanofilter (NF-MFI) membrane. MFI and SDI indicated that deep bed filtration with in-line flocculation was better pre-treatment than flocculation alone as colloidal particles are removed after this pretreatment. UF-MFI and NF-MFI indicated that these pretreatment cannot remove dissolved organic matter as the fouling reduction was smaller. Detailed molecular weight distribution (MWD) of seawater organic matter was examined after different pretreatments. MWD of the initial seawater mainly ranged from 1510 Da to 130 Da. Deep bed filtration with in-line flocculation removed relatively large molecular weight of organic matter (1510-1180 Da), while the small molecular weights (less than 530 Da) were not removed. [ABSTRACT FROM AUTHOR]