EFFECT OF HYDRAULIC RESIDENCE TIME ON Cr(VI) REMOVAL USING CONSTRUCTED WETLANDS

EXTENDED ABSTRACT The removal of chromium from water and wastewater has caused increased research interest in recent years. Chromium exists in the environment mainly in one of two valence states: a) trivalent Cr(III), and b) hexavalent Cr(VI) form. Cr(VI) enters the environment primarily through industrial processes including the production of steel and metal alloys, chrome plating, dyes and pigments, as well as leather and wood preservation. Cr(VI) compounds are highly soluble at neutral pH. Constructed wetlands (CWs) are presently considered the most promising technology of wastewater treatment due to their low cost, simple operation and maintenance, and favourable aesthetic appearance. Several studies have shown the overall effectiveness of CWs in treating not only municipal wastewater but heavy metals as well. CWs achieve high pollutant reduction rates because the planted vegetation can adapt to the existing operating conditions.