Heavy metal removal from wastewater in fluidized bed reactor
An innovative process for removing heavy metals including Cu, Ni and Zn from industrial wastewater has been developed. The new technology was based on inducing the nucleated precipitation of heavy metals on the sand surface in 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 and 95% when influent heavy metal concentrations were 10 and 20 mg/l, respectively. 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 effect on heavy metal removal efficiency when HRT was greater than 7.1 min. Scanning electron microscope (SEM) analysis indicated that carbonate injection with a drip-wise manner was more conducive than that with a slug dosing manner for precipitation to be coated on the sand surface.
Based on the finding of this study, the following conclusions can be drawn:
1.
This technology which was based on inducing nucleated precipitation of heavy metals on sand surface in a fluidized bed is viable for removing heavy metals from industrial wastewater.
2.
pH played a significant role in the process of heavy metal removal. The optimum pH value was 9.0–9.1 for the simultaneous removal of Cu, Ni and Zn. At this pH value, heavy metal removal efficiency could be achieved as high as 92 and 95% when influent metal concentrations were 10 and 20 mg/l, respectively. There was no need for sludge dewatering since the removed metals became a part of the dry chemical pebbles.
3.
When pH was greater than 8.7, above 92.4% of the precipitation was composed of hydroxide.
4.
SEM analysis shows that the drip-wise dosing of carbonate could induce the “nucleated precipitation” to a higher extent than the slug dosing condition. The metal coating was more efficient when carbonate was applied to the reactor at a gradual pace.
Heavy metal removal from wastewater in fluidized bed reactor
An innovative process for removing heavy metals including Cu, Ni and Zn from industrial wastewater has been developed. The new technology was based on inducing the nucleated precipitation of heavy metals on the sand surface in 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 and 95% when influent heavy metal concentrations were 10 and 20 mg/l, respectively. 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 effect on heavy metal removal efficiency when HRT was greater than 7.1 min. Scanning electron microscope (SEM) analysis indicated that carbonate injection with a drip-wise manner was more conducive than that with a slug dosing manner for precipitation to be coated on the sand surface.
Based on the finding of this study, the following conclusions can be drawn:
1.
This technology which was based on inducing nucleated precipitation of heavy metals on sand surface in a fluidized bed is viable for removing heavy metals from industrial wastewater.
2.
pH played a significant role in the process of heavy metal removal. The optimum pH value was 9.0–9.1 for the simultaneous removal of Cu, Ni and Zn. At this pH value, heavy metal removal efficiency could be achieved as high as 92 and 95% when influent metal concentrations were 10 and 20 mg/l, respectively. There was no need for sludge dewatering since the removed metals became a part of the dry chemical pebbles.
3.
When pH was greater than 8.7, above 92.4% of the precipitation was composed of hydroxide.
4.
SEM analysis shows that the drip-wise dosing of carbonate could induce the “nucleated precipitation” to a higher extent than the slug dosing condition. The metal coating was more efficient when carbonate was applied to the reactor at a gradual pace.
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