COST EFFICIENT SLUDGE LIQUOR TREATMENT / Kostnadseffektiv behandling av rejektvatten
For sludge liqours the normal way is to lead the different reject water streams back to the inlet of the treatment plant thus producing high and irregular internal loads that can be difficult to control and which cause problems for the normal treatment. A solution to the problem is to introduce a separate treatment. Sludge liquors, discharge from land-fills and some industrial waters are highly concentrated in nitrogen and the known treat- ment methods for example ion exchange, ammonia stripping, membranes and biological nimfication/denitrification are expensive. Two new methods have been tested in pilot-scale during 18 months and compared with conventional nitrification/denitrification. The methods tested are nitritation/denitntation and aerobic de- ammonification.
The operational costs for a biological nitrogen-removal process is highly dependent on the realation COD/N. Normally external carbon must be dosed because the COD available for denitrification in the sludge liquor is not enough. Another cost is the high oxygen demand for the nitrification process. This paper presents results from pilot scale trials with alternative biological treatment of nitrogen-rich waste water. The methods tested have a lower carbon and oxygen demand than conventional nitrification/denitrification.