Sustainability and membrane processing of wastewater for reuse

Sustainability has various meanings in the context of water reclamation and reuse. In one sense it acknowledges that to sustain our water supplies we must develop technologies that can efficiently reclaim wastewater to augment natural supplies. Membrane technology is playing a vital role in this application. However a largely unasked question is how well do the membrane technologies we use and the way we operate them stand up to scrutiny based on ‘sustainable development’ criteria? Finally at the technical and operational level we have the age-old problem of fouling and its impact on ‘sustainable’ long-term operation. This paper addresses the three levels of sustainability in the context of membrane technology and water reclamation.

Membrane technology is playing an increasing role in sustaining water supplies by freeing up compromised sources such as wastewater. When the technology is evaluated in terms of the criteria for sustainable development it gets a favourable ranking. The major limitation is membrane fouling and that influences the selection of conditions for long-term sustainable operation. For the commonly used constant flux operation fouling phenomena tend to be self accelerating so that TMP transients occur. Strategies to control this involve intermittent filtration, adequate two phase flow and module design to encourage homogenous filtration.