Heavy metals that are dissolved in wastewater effluents are problematic for municipal treatment facilities, because of the added toxicity towards the biological population working at decomposing organic matter.
Heavy metals generally originate from industrial manufacturing processes, and can widely vary in nature and levels; the list of heavy metals is long:
Al, Sb, Ag, As, Be, B, Cd, Cr, Cu, Sn, Fe, Mn, Ni, Pb, Se, Th, Zn, Zr
The removal or reduction methods for heavy metals found in wastewater streams are:
Coagulation and flocculation process, including a liquid-solid separation system.
Controlled precipitation, using ph and/or specialized polymer chemistry that will target specific metals.
- Ion exchange resins, designed for specific metals.