The construction of the the first functional biofilter in Belgium was finished by mid-July at the facilities of Aquafin in Aartselaar. In November 2019 was finished its spatial integration by the construction of concrete elements around the filter. The biofilter occupies a surface area of 9 m2 and it is made of filter sand, topped off with iron coated sand and tree flakes to reduce evaporation.
On the demo site, rainwater from the roof of a service building with a surface of 220 m2 is collected in a black rainwater harvesting tank with a volume of 4 m3. A peristaltic pump with a flow of 0.5 m3/h is used to transfer the rainwater to a biofilter. The rainwater is distributed over the surface of the biofilter by perforated tubes and an overflow pipe in the biofilter prevents flooding in case of filter blockage.
After biofiltration, the water is collected by a PVC pipe at the bottom of the filter medium in a drainage well (Ø 800, h:1,5m) and discharged into the sewer with a pump. The water level in the biofilter is controlled by the outlet of the drainage pipe.
The DEMO in Aartselaar has been built in order to perform extensive research on the treatment efficiency of the system. Because of strict legislation on deep infiltration in Flanders, particularly in relation to the water quality, the demonstrator project at Aquafin was built with the following objectives:
• To test treatment performance of the Biofilter, particularly in relation to the infiltration requirements for Flanders.
• To generate empirical evidence to support the further optimisation of the Bluebloqs technology and system configuration.
• To assess and improve the acceptability of the innovation by water managers and end-users in Flanders.
The aim of the demo is to investigate the removal efficiency of the biofilter towards different pollutants in rainwater, without taking into account the local storage of the water in an aquifer. The biofilter is enclosed with high-quality seating elements, which simultaneously have an important function in enclosing the biofilter with a stable and watertight construction.
The demo in Aartselaar proofs the Bluebloqs biofilter is performing well on the adsorption of heavy metals. Additionally, the new aeration step that is tested in this demo has proven to be very effective.
The first year the focus of the testing was on heavy metals. This year we will focus more on bacterial disinfection and the effect on suspended solids, nitrate, phosphate, COD, BOD.