Long term Evaluation of the Effect of Salinity on Organic Removal and Ammonium Oxidation in a down-flow Hanging Sponge Reactor

INTRODUCTION Down-flow hanging sponge (DHS) reactors employ polyurethane sponge media to retain biomass. Wastewater is trickled from the top of the reactor and purified by microorganisms within and on the surface of the sponge media as influent flows vertically downward through the reactor. Since the sponge media of DHS reactors are exposed to the atmosphere, oxygen dissolves continually into the wastewater. Consequently, there is no need for external aeration. Furthermore, since a large amount of activated sludge accumulates on the inside and outside of the sponge media, an ecosystem with an extremely long food chain develops and the production of excess sludge is restricted (Uemura and Harada, 2010).