Nature-Based Solutions to Purify Wastewater: How Aquatic Invertebrates and Plants Can Help
Key Highlights :
Aquatic creatures may help purify our wastewater. A team of researchers has investigated how invertebrates, such as worms, non-biting midge larvae and mussels that live on the bottom of streams and ditches, may benefit wastewater treatment plants. These creatures can degrade sludge, reduce greenhouse gas emissions, and remove excess nutrients from the water together with floating plant species.
The purification of wastewater is a challenging process for wastewater treatment plants due to the production of excess sludge. This sludge is largely made up of organic material that aquatic invertebrates can feed on. Tom van der Meer, a researcher at Wageningen Environmental Research, studied how these creatures can break down this excess sludge as part of his Ph.D. research in the Aquafarm project.
Van der Meer and his team found that non-biting midge larvae degraded sludge up to five times faster than sludge in which they were absent. Not only that, their burrowing added sufficient oxygen to the sludge, preventing the formation of the powerful greenhouse gas methane.
The Water Framework Directive stipulates that the levels of nutrients such as nitrogen and phosphorus in surface water must be reduced by 2027 in all EU member states. This is to prevent the negative impact on sensitive animal and plant species, as well as to avoid the growth of cyanobacteria. However, many such substances remain in the wastewater even after purification, which means they are discharged in rivers and creeks.
Van der Meer and his team found that a combination of algae and mussels can remove almost all of these nutrients from the water. They also tested floating plants such as duckweed ferns, with excellent results. Based on these findings, two Dutch water authorities will develop a pilot treatment facility capable of purifying some 75 cubic meters of wastewater per day.
This nature-based solution to purify wastewater may be more cost-efficient as well as contributing to improving water quality in Dutch nature. With this method, wastewater treatment plants may be able to meet the Water Framework Directive and improve the quality of water in the EU.
In conclusion, aquatic invertebrates and plants can be used to effectively purify wastewater, reducing greenhouse gas emissions and removing excess nutrients from the water. This nature-based solution could be the future of wastewater treatment plants in the EU.
