In the Puur Waterfabriek (‘Pure Water Factory’) in Nieuw-Amsterdam near Emmen, the effluent from the sewage treatment plant is processed to become ‘pure water’. Although the Pure Water Factory is not an example of green-blue urban planning, it could be incorporated into green-blue developments. ‘Pure water’ refers to water that contains almost nothing besides H2O, not even the minerals found in drinking water. The water from this factory is used for extracting petroleum in Drenthe Province, where the extraction process requires very clean water. As its raw material, the factory uses the effluent from the adjacent sewage treatment plant. This water is treated using a series of phases, including a biologically active carbon filter, membrane filtration and electrodeionisation. The plant can produce up to 10,000 m3 of pure water per day, representing 25% of the total volume of wastewater generated in Emmen. At present, the water is only used for extracting petroleum, though other possible uses are being studied. An interesting detail is that the plant is relatively compact and labour-extensive. As a consequence, the cost of the water is only twice as high as the cost of producing drinking water. As a side effect, the pollutants still present in the effluent from the treatment plant are eliminated from the water and are not released into the surface water. Another advantage is that the production of pure water does not require groundwater. This type of technological development shows that closed water cycles are not a utopian concept: urban water cycles can be closed for only slightly higher costs.
The methods used were selected to ensure that virtually no chemicals are required for the process. [Puur Waterfabriek]
The Pure Water Factory is a partnership between the drinking water company and the local water board. [interview with Gerrit Veenendaal, 2011]
In Singapore, membrane filtration is used for treating all wastewater until it is of drinking water quality, after which it is recycled (see the Singapore example in Chapter 10).