The treatment of low concentration arsenic water by microwave modified spent grains

The discharge of wastewater containing heavy metals is one of the major security risks for drinking water. The heavy-metal polluted waste water treatment has long been a focus for environmental protection researchers. The new Standard for Drinking Water Quality (GB5749-2006) reduces arsenic concentration from 0.05 mg/L to 0.01 mg/L. This paper studies the treatment of low concentration arsenic (Ⅲ) water, arsenic being a representative anion in industrial wastewater by applying spent grains modified by microwave as biosorbent. The optimal modified conditions of spent grains were low-fire microwave for 7 min. Arsenic removal rate reaches 99.4 % in the waste water (pH=9, modified spent grains 10 g/L, initial arsenic concentration 0.5 mg/L, biosorption reaction 30 min). The arsenic adsorption kinetics of microwave modified spent grains conforms to quasi-second kinetics equation.