Year Established: 2014 Start Date: 2014-03-01 End Date: 2015-02-28
Total Federal Funds: $25,000 Total Non-Federal Funds: $6,083
Principal Investigators: Haizhou Liu
Abstract: Chromium(VI), known as hexavalent chromium, is a highly toxic and soluble compound that has been widely observed in groundwater across California. A new drinking water standard specific to chromium(VI) was recently proposed by the California Department of Public Health. The proposed low drinking water standard for chromium(VI) is estimated to post great challenges to Californian water systems to upgrade treatment to meet the regulation. The primary objective of this research project is to advance the mechanistic understanding of chromium(VI) conversion and formation pathways from water resources to treated drinking water, specifically by residual disinfectants and corrosion scales in water distribution system. The project will evaluate chromium(VI) transformation mechanisms over a broad range of typical groundwater chemistry conditions in batch reactors in PIs laboratory. Analytical methods will track changes in both total chromium and chromium(VI) to the very low levels that are being considered for regulations. The investigation will use advanced spectroscopic and electrochemical tools to identify the dominant reaction mechanisms that impact the occurrence of chromium(VI) in drinking water. Mass spectroscopic and UV spectroscopic measurements coupled with particle separation will provide insights into the oxidation state and molecular-scale coordination of chromium associated with various chemical processes in drinking water condition. In situ electrochemical detection of chromium transient species can be diagnostic of specific reaction mechanisms. A mathematical kinetics model for chromium(VI) formation via oxidation of Cr(III) oxidation by disinfectants will integrate the mechanistic insights and data from the laboratory-scale experiments to enable predictions of its occurrence over a broad range of water conditions. The research will enable the optimal design of treatment strategies and accurate prediction of treatment performance for chromium(VI) removal.