Ryaverket in Gothenburg
The Gryaab sewage and biogas plant
Built in 1972, Ryaverket treats and purifies waste water from the entire Gothenburg region. The plant, operated by Gryaab, has steadily expanded and now handles an average rate of 4,000 litres of wastewater per second. The inflow includes industrial water and corresponds to the usage of 832,000 people.
Innovative construction
Ryaverket cannot expand on adjacent land and has found innovative solutions so it can grow. Nitrification in bio beds instead of conventional basins is one way the plant saves on space.
From sludge to mud
Ryaverket generates some 55,000 tonnes of sludge each year. The bulk of it is composted and used as landfill. Some is stored for six months to allow harmful bacteria to disappear and can then be used as fertilizer on farmland.
From sludge to biogas
Treating sewage sludge creates biogas, which is an excellent energy source. Ryaverket produces about 60 GWh of biogas for later conversion into green fuel and receives fat and organic waste from restaurants, schools and food producers across the region to boost biogas production volume. The plant sells its raw biogas to power utility Göteborg Energi, which refines and sells it to consumers as vehicle fuel.
Heating from water
Before finally being released into the Göta Älv river, the purified water from the plant passes through a heat exchanger that extracts the heat, which is used by Ryaverket and provides 7% of Gothenburg's district heating.