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Down-flow hanging sponge (DHS) reactor that is sponge-based trickling filter was considered to be an alternative aerobic treatment system for low strength sewage treatment under tropical conditions. This study aims to determine the process performance of the DHS reactor combined with a pre-treatment sedimentation tank (SED) system installed at the municipality sewage treatment plant in Khon Kaen, Thailand over, 1,600 days. The DHS reactor was operated with three operational periods: low (0.2 kgBODm3 per day), high (0.5–1.3 kgBODm3 per day), and super rates (1.7–2.2. kgBODm3 per day). The results showed effective reductions in biochemical oxygen demand (BOD) and suspended solids by more than 74% and 78%, respectively, during the entire experimental period. Moreover, the final effluent met the Thailand discharge standard with an external short hydraulic retention time of 0.2 h. In addition, the combined system facilitates simultaneous nitrification and denitrification and effectively removed up to 43% of total nitrogen. The self-degradation of the organic compounds occurs owing to the retained sludge in the DHS reactor; this leads to undisputed clogging in sponge media. Therefore, the combined SED-DHS system could be an appropriate sewage treatment system for tropical conditions.

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 pre-treatment 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 KLa 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.