Heavy metal removal from wastewater in fluidized bed reactor

An innovative process for removing heavy metals including Cu, Ni and Zn Fro m industrial wastewater has been developed. The new technology was based on inducing the nucleated precipitation of heavy metals on the sand surface i n a fluidized bed reactor. The results showed that pH had a great effect on heavy metal removal efficiency and the optimum pH was about 9.0 to 9.1. At this pH value, heavy metal removal efficiency could be achieved above 92 a nd 95% when influent heavy metal concentrations were 10 and 20 mg/l, respec tively. When pH was greater than 8.7, above 92.4% of the precipitation was composed of metal hydroxide. Hydraulic retention time (HRT) had almost no e ffect on heavy metal removal efficiency when HRT was greater than 7.1 min. Scanning electron microscope (SEM) analysis indicated that carbonate inject ion with a drip-wise manner was more conducive than that with a slug dosing manner for precipitation to be coated on the sand surface. (C) 1999 Elsevi er Science Ltd. All rights reserved.