Process Components BIOFIT®.N
The efficient treatment of nitrogen-containing wastewaters requires both treatment steps nitrification and denitrification.
While the nitrification process requires a lot of oxygen, the denitrification process can only take place in anoxic conditions; to be precise, without dissolved oxygen, concurrently present nitrate, and a carbon source. For this reason, BIOFIT®.N organises these processes separately in two concentric ring tanks. This arrangement leads to a uniform ring-plug flow in the nitrification section, which ensures uniform operation behaviour at optimum efficiency.
The first stage of denitrification, i.e. the reduction of nitrate to elementary nitrogen, takes place in the non-aerated cylindrical inner ring of the activated sludge tank. A large amount of the nitrified wastewater is recirculated into the inner denitrification zone and a submerged mixer ensures its movement. The carbon amount in the inflowing wastewater provides the energy for the nitrate respiration. The wastewater then flows from the inner tank into the aerated outer ring, where the ammonia nitrogen oxidises to nitrate and the remaining carbon is removed.
Due to the cascades in the denitrification and nitrification process a sludge is formed that can be easily separated from the wastewater via sedimentation in the post-treatment. Especially if the reactors are very high, a degassing stage will be placed before the post-treatment to avoid gas release and resulting flotation effects. The excess sludge is fed to the sludge treatment.