Treatment of waste water containing chromium (VI)

In the production of chromium and in the process of transportation of chromiumcontaining materials, contamination of natural waters and soils with chromium compounds inevitably occurs. In this paper, the sorption of chromium (VI) ions with carbon sorbents is studied as a method for treating waste and natural water contaminated with chromiumcontaining compounds. Sorption method of extraction and concentration of elements is one of the most effective and simple technological method of chromium extraction. For extraction of chromium (VI), carbon sorbents obtained from recycling of wheat grains waste (RWGW) (wheat husk or bran) modified with ammonium nitrate were used. RWGW (recycling of wheat grains waste) + NH4NO3 (3%), RWGW (recycling of wheat grains waste) + NH4NO3 (5%), RWGW (recycling of wheat grains waste) + NH4NO3 (7%) were used. Chromium sorption was investigated depending on various factors. It has been established that the most effective sorbent is RWGW (recycling of wheat grains waste) + NH4NO3 (3%), with which it is possible to extract chromium by 98% from solutions at pH=1 in 30 min. This sorbent has been tested for industrial wastewater treatment containing up to 36 mg/L of chromium (VI) ions. The metal recovery rate was 95.2%. The obtained results indicate the prospects of application of RWGW (recycling of wheat grains waste) + NH4NO3 (3%) for wastewater treatment from chromium (VI).