Performance of rotating cage biological contactors based on the partial nitrification of immobilized bioactive fillers

Abstract

The rotating cage biological contactors (RCBC) is based on the partial nitrification immobilization of bioactive fillers, incorporating the advantages of traditional the rotating biological contactor (RBC). The RCBC is more energy-efficient, with higher ammonia oxidation rate (AOR) and nitrite accumulation rate (NAR) levels compared to the RBC Under the conditions of different rotational speeds and immersion rates of an RCBC, the volumetric oxygen transfer coefficient (KLa) was measured. The experimental results show that these two factors significantly affected the KLa of the reactor, which ranged from 1.08 to 42.02 h−1. Regarding long-term ammonia oxidation performance, the RCBC can successfully start partial nitrification in only 5 days. After stable operation, the AOR was 23.34 ± 0.55 mg (L·h)−1, with an NAR of 93.42 ± 0.84 %. This indicates a good adaptability to variations in influent ammonia nitrogen (NH4+-N) in the range of 95.92–403.14 mg·L−1 and good resistance to free nitrous acids (FNA). In addition, high-throughput sequencing analysis showed that the operation mode of the RCBC could effectively inhibit the growth of nitrite-oxidizing bacteria (NOB) in immobilized bioactive fillers, and the internal oxygen-limited environment provided favorable conditions for reducing the relative abundance and activity of NOB. In this study, a partial nitrification device was established by immobilized bioactive fillers in the form of an RCBC for the first time, providing a partial nitrification technology without aeration.