Sludge disposal is not the only major expense for sewage treatment plants; nitrogen elimination also consumes a great deal of energy. Typically, nitrogen removal is accomplished through the combination of nitrification and denitrification, involving high aeration. In order to reduce costs a less air intensive process is required. The deammonification process is ideal. In the nitrification process, about 80 percent of the ammonium is first oxidised up to the level of nitrite. In the second step, the remaining ammonium is oxidised into nitrogen with nitrite by anaerobic oxidising bacteria. The slow-growing Anammox bacteria are particularly well-suited to this process. The deammonification process only uses about 40 percent of the oxygen needed for conventional nitrification processes. A carbon source is not required.
There are many municipal wastewater treatment plants currently working with the DEMON® system. It is based on a development at the University of Innsbruck; Demon GmbH developed it further and patented it. The DEMON® system is used for the removal of nitrogen in the sludge water of a sewage plant. Demon GmbH has demonstrated its use in sludge water and in the biology of the sewage treatment plant on an industrial scale. This is patented as EssDE®. However this is far less common than the DEMON® System.
ELIQUO STULZ works closely with it’s Dutch sister company ELIQUO WATER & ENERGY BV, and both companies have already implemented systems for nitrogen removal from sludge water in sewage treatment plants.