NITRIFIKATION I BIOBÄDD OCH DENITRIFIKATION I EN HÖGBELASTAD AKTIVSLAMANLÄGGNING – DRIFTERFARENHETER FRÅN RYAVERKET / Post nitrification in a trickling filter and predenitrifaction in a non-nitrifying activated sludge system – operational experience from the Rya WWTP
The Rya Wastewater Treatment Plant, serving the Göteborg Region on the West Coast ofSweden has been ex- ended for nitrogen removal. The process includes post nitrification in trickling filters and predenitrification in non-nitrifying activated sludge system. In this paper some experience from the first year of full-scaleoperation will be related. The staied effluent standard of 15 g N/m3 can be met using this process. Some nitrificarion takes place in the activated sludge system despite the low aerobic SRT. This could be due to nitrifiers washed from the trickling filters to the activared sludge sysiem. The nitrifying trickling filters were subject to a predator attack chirenomide larvae, with resulting deterioration ofthe nitrification rate. The deterioration stopped when the trickling filters were flooded.