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Treating wastewater locally


Wastewater treatment could be made more efficient by decentralising it, according to Danish company Grundfos. A small-scale, mobile wastewater treatment plant developed by Grundfos is being installed and tested in small municipalities to demonstrate the flexibility that decentralised wastewater management can bring.

Decentralisation would mean that wastewater could be treated close to where it is produced, and returned to the natural environment there, rather than being transported to a central treatment works for processing. The decentralised approach would generate environmental benefits because infrastructure to transport the wastewater would not be needed, with associated energy savings and greenhouse gas emission reductions. The treated wastewater could be reused locally rather than pumped back into an energy-intensive large-scale water distribution network.

In addition, the Grundfos mini treatment plant – known as the BioBooster – is based on “ultra filtration” technology that uses multiple membranes that are so fine that even bacteria cannot pass through them. The quality of the resulting treated water is well above the standards set out in the European Union's Bathing Water Directive (2006/7/EC) and can therefore be discharged into rivers, or used for purposes such as irrigation.

Grundfos says that the BioBooster can encourage water reuse, thus reducing the pressure on fresh water sources. Less than 1% of water on earth is usable, and “water pollution and scarcity pose a real threat for us and future generations,” the company says. The BioBooster could be valuable to developing countries with large agricultural sectors and irrigation water needs, especially countries suffering water shortages, such as the countries of North Africa and the Middle East. The BioBooster is also scaleable, with an adjustable capacity equivalent to the wastewater produced by 500 to 5000 people. Users can start with a small-scale facility and add capacity as their needs increase.

The BioBooster has been tested in a variety of locations. The Danish island community of Samsø installed a BioBooster when one of its water treatment plants reached the end of its life. The BioBooster was an alternative to pumping water 20 kilometres to another treatment plant on the island. Grundfos said that for Samsø, the BioBooster proved to be both more sustainable and 30% cheaper than pumping the wastewater to a centralised treatment site.

A BioBooster was also installed at Denmark's largest organic dairy, Thise Mejeri, near Roslev in northern Denmark. The dairy now treats all its own wastewater. The cleaned water, which retains minerals and nutrients, is used for irrigation, while the sewage sludge separated from it is used for the production of biogas. Thise Majeri is now “on the cusp of zero discharge,” Grundfos says.