N E D E R L A N D S I N S T I T U U T V O O R E C O L O G I E ( N I O O - K N A W )N E T H E R L A N D S I N S T I T U T E O F E C O L O G Y ( N I O O - K N A W )

Poop is GoldWant to know more? Ask Dr. Tania Fernandes: T.Fernandes@nioo.knaw.nl

Sewage and wastewater treatment systems in the Netherlands serve their purpose, but leave large amounts of useful substances to go to waste. Researchers at the Netherlands Institute of Ecology (NIOO-KNAW) are working on a new treatment method that uses bacteria and microalgae and reclaims these valuable substances. It goes to show that learning from nature pays – and it’s interesting too! So join us and learn all about the gold we call ‘poop’.

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Who?Wastewater treatment in our sustainable NIOO-building is already a major improvement over conventional systems. Special vacuum toilets require 5 to 10 times less water to flush. The ‘black water’ from these toilets is much more concentrated than raw sewage. That’s actually a good thing, as the high concentration of fecal matter – something we usually try to get as far away from us as possible – contains carbon and nutrients that other organisms need. So for NIOO, the ideal treatment system is very much a local one.

What?

Groundwater is used to flush the toilets, and the black water flow is processed immediately. First it is led into an anaerobic reactor filled with bacteria that can grow in the black water and produce methane. The gas is used to heat up the anaerobic reactor to 35°C, accelerating the growth of the bacteria. What is left goes into a microalgae reactor.

How?

At NIOO, we consider microalgae to be more than just tiny green plants. Certain members of the Chlorella-family will grow on the wastewater that comes out of the anaerobic reactor, which has a unique composition. These algae can absorb useful substances, such as phosphate and nitrogen, from our feces. All they ask in return is light and CO² (and any CO² not released into the atmosphere helps to reduce the greenhouse effect).

P

P+ =N

N

2CO

Wat

er s

aved

Groundwater

Vacuum pump

Energy source

Biogas Elements

Vacuum toilet

We use vacuum toilets that only need one litre of water per �ush. Not only does that save water, it also makes the wastewater more concentrated, which means it’s easier to recover valuable substances.

Anaerobic reactorThe anaerobic bacteria produce biogas and kill pathogens.

Groundwaterinstead of drinking water

Gro

undw

ater

Black water is made up of urine, feces, �ush water

and toilet paper

Temperature is kept at 35°C

Solar panels supply extra energy whenever necessary

is produced by bacteria. It is burned to heat the anaerobic reactor

35°C /95°F

Groundwater

Microalgae bioreactorMicroalgae assimilate nutrients from the processed black water and store them in their cells.

CO2 and light are added to ensure optimal growth of the microalgae.

Recovering resources

are recovered by the microalgae and recycled, e.g. as fertilizer or as raw material for other products.

Helophyte filter & pondMarsh with reeds and sand layers

with di�erent grain sizes. This �lter provides �nal puri�cation.

The water is �rst discharged into a pond. It then slowly percolates

through the soil into the ground-water aquifer.

Additional benefit

Pharmaceutical residues in the water

People in the Netherlands pop a lot of pills. From birth control pills and painkillers to more specific kinds of medication. Residues from these medicines end up in our surface water when we go to the toilet. There, they can affect plants and animals. NIOO is exploring ways in which its experimental water treatment system may filter out these residues, stopping them from being released in nature. We have already been able to confirm that our microalgae treatment is very effective at removing some of them.

How do we research this?At NIOO, we’re convinced that our bacteria- and microalgae-based system produces water clean enough to be released back into the soil. That is why we are testing different kinds of microalgae and different versions of our treatment system. What is the best way for the microalgae to grow on our black water? And does that give us back all valuable nutrients? In addition to answering such questions, NIOO is trying to upscale the system and minimalize its energy consumption. A new, larger version has already been installed in the NIOO grounds.

And why?NIOO does original research into fundamental questions, while aiming to learn from nature. What we learn we aim to apply in society. Phosphate, for instance, is essential for making fertilizer and we are running out of it. It can be found in our urine and feces, but our current sewage systems do not recover it. Developing a new treatment system will help us close the cycle! Phosphate from our food that is not assimilated by the human body can be recovered and recycled as fertilizer, or as a resource for something else. Meanwhile, the flush water becomes groundwater once more, and can be used to flush our vacuum toilets again. A major bottleneck for upscaling the system in the Netherlands is the lack of sunlight. But once a solution has been found, our treatment system will truly turn our poop into a goldmine.

P

P+ =N

N

2CO

Wat

er s

aved

Groundwater

Vacuum pump

Energy source

Biogas Elements

Vacuum toilet

We use vacuum toilets that only need one litre of water per �ush. Not only does that save water, it also makes the wastewater more concentrated, which means it’s easier to recover valuable substances.

Anaerobic reactorThe anaerobic bacteria produce biogas and kill pathogens.

Groundwaterinstead of drinking water

Gro

undw

ater

Black water is made up of urine, feces, �ush water

and toilet paper

Temperature is kept at 35°C

Solar panels supply extra energy whenever necessary

is produced by bacteria. It is burned to heat the anaerobic reactor

35°C /95°F

Groundwater

Microalgae bioreactorMicroalgae assimilate nutrients from the processed black water and store them in their cells.

CO2 and light are added to ensure optimal growth of the microalgae.

Recovering resources

are recovered by the microalgae and recycled, e.g. as fertilizer or as raw material for other products.

Helophyte filter & pondMarsh with reeds and sand layers

with di�erent grain sizes. This �lter provides �nal puri�cation.

The water is �rst discharged into a pond. It then slowly percolates

through the soil into the ground-water aquifer.