NAS - New Activated Sludge system
NAS® (New Activated Sludge) represents a unique active sludge system in which anammox bacteria constitute a part of the biomass. These micro-organisms ensure a very effective removal of the nitrogen during aerobic purification. An aerobic purification step is often necessary to enable the removal of the remaining COD fraction and nutrients and to facilitate effluent re-use. The NAS® system can be configured with a variety of sludge/water separation systems, e.g. post-settling tanks, flotation or membrane separation. In case an active sludge system or membrane bio reactor (MBR) is configured within a NAS® system a number of additional advantages are obtained, e.g. a significant improved effluent water quality and the option to reduce the dimension of the aerobic purification system.