Investigation of Bioaugmentation and Other Process Changes and Their Effects on Ammonia Removal at a Municipal Wastewater Treatment Facility

Abstract

The primary objective of this research was to determine the process changes responsible for the improvement of ammonia removal in a municipal WWTF, in addition to determining the success of a pilot bioaugmentation project. Bioaugmentation began in August 2020, a splitter box was installed to control flow entering the rotating biological contactors (RBCs) in November 2020, and the primary clarifier pH was increased in February 2021. The ammonia treatment issues of the WWTF occurred in only one of the two RBC treatment trains and results were confounding regarding the process change responsible for improved treatment, however, the splitter box was most likely responsible. Four major ammonia oxidizing and nitrite oxidizing bacteria were present in the RBC biofilm samples, including Nitrosomonas, Nitrosospira, Nitrospira, and Candidatus Nitrotoga. Overall, it appeared bioaugmentation had no effect on the WWTF and operational changes were responsible for ammonia treatment improvement.