ASSESSMENT AND TREATMENT OF Cr⁶⁺ POLLUTION IN THE HAIBEI CHEMICAL PLANT IN QINGHAI PROVINCE

The Haibei Chemical Plant has stopped production for 15 years, but the Cr⁶⁺ pollution of the site is still serious. Investigation shows that the original pollutant source is the production waste and the remaining liquid waste, which leached into the soil with rainfall and polluted the soil and the groundwater. The quality of soil and groundwater is evaluated with groundwater quality standard and pollution index method. The result reveals that an area of 0.75 km² has been seriously polluted. The average Cr⁶⁺ content in the unsaturated zone is detected to be 67.67×10^-6, which exceeds the standard of Grade V water. By analyzing the hydrogeological conditions and the assessment data, it is suggested that soil replacement and pumping method should be adopted to clean up the Cr pollutant from soil and groundwater in the area.