Aquafarm: treating wastewater and harvesting valuable organisms
Smarter handling of waste and wastewater is one of the greatest challenges of our time. Wageningen University & Research is working within the AquaFarm project on a major breakthrough: treating wastewater in a cyclical way while producing valuable organisms.
Given enough time, nature tends to clean itself in ways that can teach us a lot about how to handle wastewater. The AquaFarm project is inspired by natural mechanisms while aiming to treat wastewater in a manner that is much faster, more focused and takes up much less space. Plants and animals do the heavy lifting. This is not a new concept in itself: algae are already used on a small scale to recover phosphorus from waste sludge. The novelty of Aquafarm is that the purifying organisms produced can also be used as a source of high-grade products such as proteins, cellulose and food.
The secret is in cascading, explains Professor Piet Verdonschot of Wageningen University & Research. “We set up a series of linked containers, each containing one organism grown under ideal conditions, and run the wastewater through them. Coupling the compartments to each other allows the organisms to work together and bring out each other’s strengths. Moreover, we can harvest the organisms regularly to produce valuable substances very efficiently. This includes protein and cellulose, which can be used for a wide range of quality products.”
According to Verdonschot, the process begins with small organisms such as the bacteria familiar from classical water treatment processes. These are followed by small worms, mussels, fish and higher plant species. “We ensure that we deploy organisms with the right added value in the correct sequence.”
Wastewater: no longer waste
Wageningen University & Research is working on this project with Radboud University Nijmegen. The flora segment of the research takes place in Nijmegen and the fauna segment in Wageningen. The non-academic partners are the water boards Rivierenland, Hollands Noorderkwartier and Stichtse Rijnlanden. “Wastewater has in practice not been seen as waste for quite some time,” Verdonschot observes. “The idea that we must eventually deal with wastewater in a completely cyclical way has been accepted for some time. Aquafarm is simply translating that concept into practical applications.”
Decentralised wastewater treatment
These applications need not be limited to the wastewater that finds its way to the central water treatment plants of the water boards, emphasises Verdonschot. “You can also deploy the Aquafarm concept in a decentralised way, for instance at district level or for a company that produces heavy metals. You can then make the process far more precise, for example by only using organisms that are very good at recovering copper and zinc.”
Clean water in circular cities
The cities of the future should have a circular way to treat waste and have plenty of clean water which has been treated in a sustainable way. They should also have less waste sludge, lower energy consumption and a smaller CO2 footprint. Verdonschot: “The proof of concept has showed that this works. Now we want to move faster and make real steps toward a practical application. We can’t manage that within a year. It takes time to make the right selection of organisms in the cascade. For this, we test many organisms, which must pass a growth phase during the test. In addition, the available budget determines how many tests we can perform at the same time. But in ten years we will be much further ahead with the development.’