Towards a water-wise world Annual report 2014

Kerusha Lutchmiah doctorate 

Recovering water from wastewater using forward osmosis

2 July 2014Research
Kerusha Lutchmiah

Kerusha Lutchmiah

Wastewater is an interesting source of water, energy and other components. Over the last few years, KWR has been conducting the Sewer Mining project. Part of this project involves the development of a technical concept to extract high-quality water from wastewater, water which would be a suitable and – over time – lower-cost alternative for industrial process water. This would reduce the pressure on drinking water sources. Kerusha Lutchmiah’s research focused primarily on the forward osmosis part of the Sewer Mining concept, and receives a doctorate from TU Delft.

The Sewer Mining concept entails the extraction of water using forward osmosis (FO), an innovative membrane process which makes use of the natural process of osmosis. The osmotic solution is the driving force in FO processes, and in this regard they differ from the better known pressure-driven membrane processes, such as reverse osmosis (RO) and nanofiltration. The concept implements FO in a closed system, so as to recycle the osmotic solution and to recover the high-quality water. This separation occurs in a recovery process (e.g., RO), which is the energy-consuming step in closed FO applications. Wastewater, on the other hand, contains organics, which, through anaerobic digestion, can be converted into renewable energy (biogas). The biogas can then be used in the recovery process, thus reducing the total energy consumption of the process. In addition, the concentrated nutrients from the digested sludge can be recovered and recycled, for example, as a fertiliser.
KWR is currently drawing on this acquired knowledge for new application-oriented projects. Forward osmosis has a great potential, and its application can lead to a more economical and sustainable treatment of wastewater. This fits in with the development of a circular economy and in the way wastewater is perceived: not as waste, but as a useful source of water, energy and other components, such as nutrients.

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Scientific publications
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Forward osmosis for application in wastewater treatment: A review

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