Urine safe hands

Treating urine separately from other waste water could save money on processing sewerage, allow more raw materials to be reclaimed, use less energy and make sewers less smelly.

Delft University of Technology researcher Jac Wilsenach explored the subject for his PhD, and believes that applying this research could lead to revolutionary changes in waste water management.

Urine accounts for less than one per cent of waste water, but it contains 50-80 per cent of the nutrients in it, putting a strain on sewer water purification installations. Preventing urine from mixing with other waste water in the first place, as has occurred in sewers for over a century, would be far more efficient.

There is growing support for collecting and purifying urine separately. By separating urine, phosphate and nitrogen can be more effectively removed, and phosphate can be reclaimed as a raw material for use in fertilisers and detergents. Urine accounts for at least 50 per cent of the phosphate and 80 per cent of the nitrogen in waste water.

In Sweden and other countries, experiments have been conducted involving separate urine collections. Backed by a STOWA grant, Wilsenach researched the possibilities and consequences of following this principle in the Netherlands.

He concluded that if 50 per cent of the urine were separately purified, it would save 25 per cent of the energy needed for the entire purification system. Moreover, the stench of the sewer would be lessened, environmental pressure on the surface water would be reduced, and sewer pipes would be better protected against rot.

A requirement for separating urine is an appropriate toilet, on which men also sit to urinate, or a dry urinal. The urine can be collected in tanks and periodically transported to a purification installation. Wilsenach also explored the possibility of processing the urine in decentralised facilities in his research.