Keywords: nitrogen, phosphorus, municipal wastewater, municipal solid waste, substance flow analysis, time series, Finland
Flows of nitrogen and phosphorus in municipal waste: a substance flow analysis in Finland
Nitrogen (N) and phosphorus (P) are two nutrients contributing to several environmental problems, particularly eutrophication of surface waters. Leakages of these nutrients occur through human activity. In this study, the flows of N and P in the Finnish municipal waste system in 1952–1999 were determined and analysed using substance flow analysis (SFA). Nutrient flows in both wastewaters and solid waste peaked in 1990, after which they declined until 1994 but thereafter increased again although remaining lower than in 1990. At the end of the 1990s the wastewater and solid waste from municipalities and rural households contained ca. 7.0 kg N person-1 a-1 and 1.1 kg P person-1 a-1. Untreated wastewater contained three times more N and four times more P than solid waste. The amounts of N and P involved in recycling increased over the study period being 10% for N and 50% for P at the end of the 1990s.