Treatment of the Processing Wastewaters Containing Heavy Metals with the Method Based on Flotation

The aim of the studies carried out at full technological scale was to indicate optimal systems of the two-stage precipitation and coagulation (PIX 113 - SAX 18, PAX XL1 - SAX 18, ALCAT 102 - lime milk and SAX 18 - PAX 16) in the process of eliminating heavy metals from wastewaters made in the processing plant producing sub-systems for domestic appliances. Precipitated pollutions were thickened by flocculation and separated by hydrogen peroxide enhanced pressure flotation. The experimental installation of maximal flow capacity: 10.0 m³/d consisted of: the storage-equalization tank, the processing pipe reactor, the pressure flotation station, and the reagent preparation and dosing station. Optimal doses of reagents and a flocculent as well as pressure and saturation time were defined for which maximal reductions in the load of heavy metals were achieved. The usefulness of hydrogen peroxide as a means of enhancing flotation was tested. The use of two-stage precipitation permitted the reduction in heavy metals (Cd, Cu, Cr, Ni, Sn, Zn), eg by applying ALCAT 102 - lime milk at the level exceeding 80%.