Wastewater treatment

Responsable: Jules van Lier

Waste water treatment is needed to full-fill the Water Framework Directive. However, more and more attention is paid to the fact that waste water is also a potential resource of city water and/or industrial water. Crucial is treatment at specification at acceptable costs with the aim of resource recovery at various levels, such as energy, fertilizing agents such as phosphates and of course water. In the Netherlands specific programmes are developed to increase the energy production at waste water treatment plants by for example the production of green gas (from sludge) that can be injected in the existing natural gas distribution system. This could even applied to black water in a decentralized system where the black (faeces), yellow (urine), grey (bathing and kitchen) and white (rain) streams are (partly) separated. The yellow stream can e.g. be used for the production of fertilizer. Phosphate recovery is becoming an important issue since this compound is getting scarce and prices are rising dramatically. Finally, the water of the effluent of a waste water treatment plant is a resource for industry and agriculture. In the Netherlands, 80% of the fresh water use is industrial and when domestic waste water effluent is used for industrial application less pressure is laid on the precious water sources.