Structural optimization of the porous section in a water-sparged aerocyclone reactor to enhance the air-stripping efficiency of ammonia

Abstract

The water-sparged aerocyclone (WSA) reactor is a new air-stripping system with high efficiency for ammonia removal from wastewater. To improve its mass transfer performance and establish design principles, the porous section, including the arrangement mode, distribution and diameter of the spray holes of the WSA, was optimized based on the mass transfer coefficient for the air-stripping of ammonia from water. As a new concept, the critical distance between two adjacent spray holes, lC, and its calculation formula were presented. The results showed that the spray holes should be arranged in a square mode, and the optimum distance between adjacent spray holes was approximately 1.28 lC. The proper axial length of the porous section accounted for approximately 78% of the depth of the central inner tube in the WSA. A larger spray hole diameter is beneficial for mass transfer, and KLa∝dh0.13. However, as a design guide, the spray hole diameter should be less than 0.133 times the annular width of the WSA, i.e., dh < 0.133lA, from a technological and economic viewpoint. These results could be used as a guide for the design of a WSA with good mass transfer performance.