The challenges of scaling-up water recycling

More extensive use of managed recycling of water offers one of the most promising opportunities for coping with ever-growing pressures on water resources, but there are significant challenges in scaling up this approach, cautions Professor Hallvard Ødegaard of NTNU – Norwegian University of Science and Technology.

According to Ødegaard, water recycling is so important because present water systems will just not suffice in the future, meaning analysis of the benefits and challenges of recycling water is essential to planning, building and operating future water systems. Indeed, he is to chair a technical session on recycling today, but he says that he feels this topic is so important that he will also raise these issues during the IWA Distinguished Fellows panel discussion that he will lead during the closing plenary session on Thursday.

The benefits of water recycling are that less water is taken from external water sources, discharges and pollution are reduced, different quality waters can be produced for different purposes, and the urban water environment can be improved, explains Ødegaard. However, there are also many challenges. The safety of the recycled water is key, he says, including reducing the risk of cross-connections between pipes of different water quality. A practical challenge as far as more extensive recycling is concerned is the time it takes to implement new systems and change current systems, given that they are built to last 50-100 years and that utilities are generally conservative as far as change is concerned.

‘We need examples of these new systems, in order to see how they work in practice and get a better understanding of the benefits and challenges,’ says Ødegaard. ‘There are many (mostly smaller) projects around the world now and it may be they will show that we need decentralised or semi-centralised systems in order for water recycling systems to become successful.’

The four presentations to be made during the session Ødegaard will chair highlight some of the important themes around recycling: the impact on groundwater quality, recycled water pipe systems, ceramic microfiltration and on-site greywater recycling.

Professor Ødegaard chairs ‘Benefits and problems of water recycling’, the third of today’s technical sessions on water reuse, in room 5B.