A method of removing one or more heavy metals from municipal wastewater by
use of a membrane separation process is disclosed. Specifically, the
following steps are taken to remove heavy metals from municipal
wastewater: (a) collecting a municipal wastewater containing heavy metals
in a receptacle suitable to hold said municipal wastewater; (b) adjusting
the pH of said system to achieve hydroxide precipitation of said heavy
metal in said municipal wastewater; (c) adding an effective amount of a
water soluble ethylene dichloride-ammonia polymer having a molecular
weight of from about 500 to about 10,000 daltons that contain from about
5 to about 50 mole percent of dithiocarbamate salt groups to react with
said heavy metals in said municipal wastewater system; (d) optionally
clarifying the treated wastewater from step c; (e) passing said treated
municipal wastewater through a submerged membrane, wherein said submerged
membrane is an ultrafiltration membrane or a microfiltration membrane;
and (f) optionally back-flushing said membrane to remove solids from the
membrane surface.