Municipality
Danish water-treatment plants annually treat about 630 millions cubic metres waste water. This comes from toilets, households and from the industry. The existing sewage systems do not allow for the separation of household waste water from that coming from the industry, so everything is mixed. It should, however, be noted that many of the larger industrial plant have their own local water treatment plants.
The treatment of waste water produces approximately 1.2 million of tons of wet sludge, corresponding to approximately 160.000 tons of dry sludge per year. The content of the dry sludge that is spread over the fields differs from municipality to municipality. Approximately half of the sludge is used by the farming industry while the rest is burnt off, dumped or used for other purposes than as a fertilizer.
Sludge
