Municipal wastewater

This report summarizes the most important findings regarding the status of the municipal wastewater sector in Norway, and covers topics like expenditures and investments, fees, compliance with treatment permits, discharges of nitrogen, phosphorus, heavy metals, a few organic pollutants, treatment efficiencies, number of wastewater treatment plants, capacity, number of people connected, heavy metal content in sewage sludge and disposal of sewage sludge.

In 2018 there were 2 717 wastewater facilities in Norway with a capacity of more than 50 population equivalents (pe) according to the municipalities reports to the Norwegian Environment Agency. They treated wastewater from 87 per cent of Norway’s population. The share of the population connected to advanced treatment plants (chemical and/or biological treatment) were 63 per cent, while 22 per cent had mechanical or other treatment and 2 per cent of the population had direct discharges (untreated wastewater). The remaining population was connected to the around 330 000 small wastewater facilities (less than 50 pe and thus including small individual facilities), which normally constitute a sludge separator, possibly with some additional filtration device in the end.

In total, the discharge from the municipal wastewater sector in 2018 is estimated to around 1 500 tonnes of phosphorus and 19 400 tonnes of nitrogen including also small wastewater facilities less than 50 pe and estimated leakage.

Because of the North Sea Declaration treatment of wastewater with discharges into the water basins leading to Skagerrak and the North Sea – the location of the most sensitive areas, has given highest priority since the 1990s. These areas are bound by stricter discharge regulations compared to the rest of the country (Western-, Mid- and Northern Norway). This is also reflected in the statistics of large waste¬water facilities ( 50 pe) with noticeably lower phosphorus discharges per capita connected to treatment plants in the North Sea counties (0.05 kilogram) compared to the rest of the country (0.46 kilogram). The average treatment efficiency – removal of polluting agents by treatment plants – for phosphorus in the North Sea counties (92 per cent) is also higher compared to the rest of the country (36 per cent). The same picture applies to nitrogen, although the differences are less noticeable. It is particularly the counties of Oslo and Akershus which show low discharges per capita of nitrogen (1,75 kilogram) combined with high treatment efficiency (64 per cent).

Compliance with treatment permits constitutes an important part of wastewater management, and the statistics show that out of 4.6 million people connected to moderate or large wastewater facilities (50 pe or larger) in 2018, around 61 per cent belong to a facility which comply with their treatment permits, 32 per cent where the facility do not comply and 7 per cent where there is unknown compliance (due to missing data about treatment requirements).

For 2018, the total amount of sewage sludge used for different purposes has been estimated to around 111 700 tonnes, measured in dry weight. Approximately 82 per cent of this amount was used in agriculture, in parks and other green spaces or delivered to soil producers.

Municipal wastewater fees set by the municipal authorities are in accordance with full cost regulations. The fee level generally varies due to differences in type of settlement patterns and geographical characteristics. The connection fee is a one-time payment by the user at the time of connecting to the existing wastewater pipeline-system. In 2019, the connection fee was on average NOK 15 000 (VAT excluded). The annual fee was on average NOK 4 100 per year in 2019 (VAT excluded).

In 2018, the municipalities’ annual costs totaled NOK 8,4 billion. The costs in the municipal wastewater sector are capital costs and operating expenditures.