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 t...

This article describes an effective procedure for reducing the water content of excess sludge production from a wastewater treatment plant by increasing its concentration and, as a consequence, minimizing the volume of sludge to be managed. It consists of a pre-dewatering sludge process, which is used as a preliminary step or alternative to the thickening. It is made up of two discontinuous seq...

The purpose of this study is to determine how the rheological characterization of centrifuged thickened waste excess activated sludge (EAS). Wastewater treatment plants (WWTP) contain a number of transport operations of suspensions with special flow characteristics. Flow characteristics, in particular viscosity related effects, vary from very water-like to strongly non-Newtonian. This study use...

Additional enzymes pretreatment technology can promote the hydrolysis of excess activated sludge, while increasing gas production. Single enzyme pretreatment of sludge, alkaline protease has a better effect of hydrolysis. The optimum working conditions for alkaline protease: pH value of 8.0, the solid-liquid ratio of 1:4, the enzyme concentration of 2%, the working temperature of 55°C, reaction...