Safe disposal of solid wastes generated during arsenic removal in drinking water

Abstract

Wastes generated during the treatment of water containing arsenic were mixed with Portland cement in 3 : 1 volume ratio, respectively, to produce mortars that were then used to manufacture monolithic bricks. Two different wastes, containing 1.0 × 103 and 2.0 × 103 mg As per kg of dried waste, were generated in experiments of aqueous trivalent arsenic ([As(III)] = 50 mg L–1) removal in columns filled with a mixture of zero-valent iron and sand (1%, w/w of ZVI). The mechanical tests indicated that the waste-containing bricks showed a decrease in the compression tests, while no significant differences were found in the flexural tests. Studies on arsenic leaching indicated that, in normal conditions, the amount of released arsenic is not significant, as extreme conditions are required to exceed the maximum allowable limit for non-hazardous waste. Even though the quality of the resulting mortar is lower, it is still well suited to make bricks for use in the construction of foundations or for final disposal in landfills.