Reduction of Chromium in Waste Water From Hard Chrome Plating Processes: A Review

Waste water from hard chrome is considered to be highly toxic due to the presence of chromium ions in hexavalent form and this hexavalent state of chromium is more toxic to animals and humans due to its ability to produce reactive oxygen species in cells. Such heavy metals are considered as carcinogenic to living organisms and hence either reduction of ions to trivalent chromium or removal of ions has to be done before ejecting the waste water into the environment. Many processes for reduction, neutralisation and removal of hexavalent chromium have been investigated and reviewed extensively. In the present review, studies and research carried out for the removal of chromium from waste water of hard chrome plating effluent are summarised. The study was carried out on the aspects such as percentage removal, efficiency and optimum operating conditions in chrome removal and reduction processes.