Positive Effects of Zeolite Powder on Aerobic Granulation: Nitrogen and Phosphorus Removal and Insights into the Interaction Mechanism

Aerobic granular sludge is considered to be one of the most promising biological wastewater treatment technologies of the 21st century. However, the long granulation time and poor treatment effect on N and P have severely limited its popularization and large-scale application. In this study, we systematically examined the strengthening effects of zeolite powder on granulation and N and P removal, and their interaction mechanism. The addition of zeolite powder shortened the sludge granulation time to 18 days and improved the average N and P removal rates by 4.48% and 2.22%, respectively. This is the result of the combined action of physical, chemical, and biological factors. The multi-pore and nutrient-rich environment of zeolite powder are beneficial to the maintenance of microbial activity and granule stability. Moreover, its adsorption to N and P enriches their respective removal strains, thereby improving their removal effect.