A newly water-sparged aerocyclone (WSA) reactor was employed for treatment of Cr(Ⅵ)-containing wastewater by direct reduction using sulfur dioxide（SO2）

and a satisfactory result obtained. The results show that a removal efficiency above 99.9% of Cr(Ⅵ) is achieved after 6 min of cycling treatment by gas of SO2 concentration 3582 mg·m-3 for the wastewater containing Cr(Ⅵ) 1134 mg·L-1. Alkaline of wastewater is beneficial to absorb SO2

go up SO2 utility

and enhance the efficiency of Cr(Ⅵ) reduction. Initial concentrations of SO2 and Cr(Ⅵ) have significant influence on the efficiency of Cr(Ⅵ) removal

whereas the effect of wastewater jet velocity is less. The efficiency of Cr(Ⅵ) removal increase with increasing SO2 concentration and decrease with increasing initial Cr(Ⅵ) concentration. Comparing with the SO2 reduction process conducted in traditional gas-liquid reactors like packed towers

this reduction process in WSA has some obvious advantages

such as no need for adjusting pH of wastewater to 2—3 before SO2 reduction

easy operation and no Cr(OH)3 deposition in reactor. So

this investigation could be a basis for developing new reduction process using SO2 for treating Cr(Ⅵ)-containing wastewater.