For the oxygenation demands in the biological treatment of wastewater, we offer the Passavant® Mammutrotor® surface brush aerator, the byword for excellency in horizontal shaft aerators. In combination with accessories such as guide baffles and modern technologies as IE4-class motors and automatic controller solutions (i.e. Aqualogic^® / Enerlogic^®), energy consumption can be reduced to state-of-the-art levels combined with low investment costs, long service life and very low maintenance requirements. Alternatively, Passavant^® Mammutrotors^® can be obtained as floating versions for waste stabilization ponds and smaller WWTPs.