Heavy metal toxicity of bottom ashes from combustion of sludge-coal water slurry in fluidized beds

This paper studies form distribution and leaching-out toxicity of eight kinds of heavy metal (Cd, Pb, Zn, Mn, Fe, Cu, Ni, Cr) in the bottom ashes, which are from co-combustion sludge-coal in different proportions (0%, 10%, 20%, 30%, 40%) in the circulating fluidized bed (CFB) devices. The results show that the burning process can conduct well and achieves the effects of treating waste and reuse of waste with the temperature of 1200 degrees Celsius and a suitable sludge/coal ratio. When the sludge/coal ratio reaches 30%, biological active part accounts for less. The leaching toxicity experiment reveals the amount of heavy metal leached out from bottom ashes is the smallest. So, the ratio of sludge/coal co-combustion had better be around 30%. © 2013 WIT Press.