engleski

Treatment of electroplating wastewaters using industrial/domestic by-products

Electroplating wastewaters have significantly contributed to the pollution of agricultural soil and water in Croatia. A total of 104 registered electroplating facilities existed in the year 2002. In most cases, EWW having a pH below 2 and metal levels few hundred to thousand times higher than the allowed values have been discharged directly into the surrounding agricultural soil and local streams. The aim of this work was to present a new, simple cost-effective system for the treatment of waste waters from electroplating and other surface processes highly enriched in heavy metals (Cr (VI), Zn, Ni, Fe) using other waste materials such as waste Fe(II)-sulfate and wood fly ash. The former was employed as a reducing agent and the latter was a neutralizing agent as well as a coagulant. Removal efficiency for analyzed elements ranged from 97.500% for copper to 99.973% for zinc. Satisfying results can be achieved already at the pH 8. The method is suitable for the purposes of wastewater treatment and disposal in compliance with environmental laws. Furthermore, it is technically simple, cost-efficient and requires less space compared to the classical methodology. According to the composition of its water extractable fraction remaining waste ash could be safely deposited on domestic waste repositories.

Chromate ; Electroplating waste water ; Ferrous-sulfate ; Heavy metals ; Wood fly ash

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