Evaluation of aquatic toxicities of chromium and chromium-containing effluents in reference to chromium electroplating industries

This study evaluated aquatic toxicities of chromium and chromium-containing laboratory samples representative of effluents from chromium electroplating industries, and compared the aquatic environmental risks of hexavalent and trivalent chromium electroplating operations. Trivalent chromium electroplating has emerged as an acceptable alternative to hazardous hexavalent chromium electroplating. This process substitution has reduced the human health impact in the workplace and minimized the production of hazardous sludge regulated under the Resource Conservation and Recovery Act (RCRA). The thrust behind this research was to investigate whether trivalent chromium electroplating operations have lower adverse impacts on standardized toxicity test organisms. Ceriodaphnia dubia and Pimephales promelas were used to investigate toxicities of trivalent chromium (Cr (III)), hexavalent chromium (Cr (VI)), and industrial effluents. In agreement with previous studies, Cr (III) was found to be less toxic than Cr (VI). Despite having several organic and inorganic constituents in the effluents obtained from trivalent chromium plating baths, they exhibited less adverse effects to C. dubia than effluents obtained from hexavalent chromium electroplating baths. Thus, transition from hexavalent to trivalent chromium electroplating processes may be justified. However, because of the presence of organic constituents such as formate, oxalate, and triethylene glycol in effluents, trivalent chromium electroplating operations may face additional regulatory requirements for removal of total organic carbon.