What are the heavy metals in the waste water and how can we treat it?

*The most commonly encountered toxic heavy metals in wastewater: Arsenic, Lead, Mercury, Cadmium

* Less common: Chromium, Copper, Nickel, Zinc

§  The sources of these heavy metals are: * Industrial, for example;board manufacturing, metal finishing and plating, semiconductor manufacturing, textile dyes

*Street runoffs

* Landfills

§  Ways of minimizing the concentrations of heavy metals :

Pretreatment of industrial effluents,Agreements for industrial effluents with fixed limits for heavy metals, Control samples from effluents.

 Removal of heavy metals:  Ion exchange, Adsorption Flotation and also Membrane filtration, Electrochemical methods. 

Common Heavy metals in wastewater: Lead, Cadmium, Nickel, Iron, Zinc, Arsenic, Mercury

This effluent is basically from electroplating industries. Best and cheapest treatment method is by primary chemical treatment. 

1. Mostly pH is acidic. Add10% lime solution. Adjust pH to7.

2. Add Poly Electrolyte (1ppm).

3. Metals get precipitated over a period of30 mins.

4. Seperate out the clear supernatant and remaining is the chemical sludge containing heavy metals at the bottom.