Effects of Using Arsenic-Iron Sludge in Brick Making

Leaching of arsenic from brick manufactured from arsenic and iron sludge has been investigated in this study. TCLP result shows that leached metal concentrations are far below the regulated TCLP limits and the quantities of metal leached from sludge are less than those from dried sludge. The results of Atterberg limits tests of moulded sludge-clay mixtures indicated that both plastic index and dry shrinkage decrease with an increasing amount of sludge in the mixture. Results of tests indicated that the sludge proportion and firing temperature were the two key factors determining the quality of brick. Increasing the firing temperature and decreasing the amount of sludge in the brick resulted in a decrease of water absorption. The appropriate percentage of sludge content for producing quality bricks was in the range of 15 to 25% by weight with a 15 to 18% optimum moisture content prepared in the moulded mixture and firing at 1000C for 6 hours. This study showed that arsenic and iron sludge could be used as brick material.