Anaerobic ammonia oxidation to nitrogen gas using nitrite as the electron acceptor (anammox process) is considered a cost-effective solution for nitrogen removal after an anaerobic pretreatment process. In this study, we conducted a laboratory-scale experiment to develop a single-stage partial nitritation-anammox process in a sponge-based trickling filter (STF) reactor, inoculated with anammox sludge, simulating the treatment of anaerobically pretreated concentrated domestic sewage without mechanical oxygen control. The influent ammonia concentration was 100 mg-N•L −1 . The K L a of the STF reactor was higher than those observed for conventional activated sludge processes. The STF reactor performed at 89.8 ± 8.2% and 42.7 ± 16.9% ammonia and TN removal efficiency, respectively, with a nitrogen loading rate of 0.55 ± 0.20 kg-N•m −3 •day −1 calculated based on sponge volume. Microbial community analysis of the STF-retained sludge indicated that both autotrophic and heterotrophic nitrogen removal occurred in the reactor.

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