Method and system for continuous simultaneous removal of nitrogen and suspended solids from wastewater

摘要

PROBLEM TO BE SOLVED: To provide a method for efficiently removing nitrogen in the secondary treated water of sewage or the like. SOLUTION: This method comprises adding a hydrogen donor such as methanol to feed wastewater, transferring the wastewater contg. the hydrogen donor to a moving bed type upflow filter 1 having a filter medium backwash function and further, recycling and adding a part of backwash wastewater discharged from the filter 1 to the feed wastewater, to biologically decompose nitrogen components in the feed wastewater and to filter and remove suspended solid in the feed wastewater. In the method, since the filtration operation and the filter medium backwash operation can continuously be performed in parallel, the clogging of a filter bed 6 due to the generation of biofilm can be inhibited from being caused and long-term continuous filtration operation can be performed. Also, since the backwash wastewater which abundantly contains organisms grown in the filter bed 6 and has a low oxidation-reduction potential, is returned to the feed wastewater, nitrogen removal from the feed wastewater proceeds even for the period of time before the feed wastewater reaches the filter bed 6 and further, the amount of organisms in the filter bed 6 is increased to effectively enhance the nitrogen removal rate.