Application of Novel Helical Liquid-Bridge Descending Flow in the Wastewater Treatment Process

Carrier packing is an important place for biofilm growth and reproduction, and the activity and quantity of the biofilm attached to it, as well as the hydrodynamic conditions, determine the effect of wastewater treatment. However, the applied packings still have difficulties, such as biofilm clogging, inadequate self-distribution performance, and uneven removal of pollutants in wastewater. The helical liquid-bridge flow has the advantages of superior self-distribution performance, small pressure drop, and fast renewal frequency. Based on this flow form, this study developed a helical liquid-bridge descending flow structured packing for enhanced biofilm wastewater treatment process. The experimental results showed that at a suitable liquid flow rate of 100 mL/min and a pitch of 2.0 mm, the film hanging time of the helical packing could be shortened to 5 days. With the increase of pitch and oxygen contents, a removal rate of more than 90% for both ammonia nitrogen and COD could be achieved, which effectively improved the efficiency of wastewater treatment. This study provides new directions for the structural design and development of biological packings, and the newly developed packing shows significant potential for optimizing the biofilm wastewater treatment process.