Research on the system efficiency. 1st prototype in Belgium.
The first demo that was implemented in 2019 is the Bluebloqs biofilter at the Research Campus of Aquafin in Aartselaar. The system at Aquafin comprises a small-scale configuration of the Bluebloqs technology for treatment of storm water run-off. The system has no installations for deep infiltration and re-use to allow for extensive analysis of the water treatment performance of the Bluebloqs biofilter, by feeding the influent to the biofilter with various compositions of pollutants typically found in storm water run-off.
At the research and water treatment facilities of Aquafin in Aartselaar, a 9m2 Bluebloqs biofilter 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:
Around the design, implementation and monitoring of the system in Aartselaar, the demo in Aarteslaar has a crucial role in facilitating the discussion on existing legislation and public opinions regarding deep infiltration. By testing the efficiency and reliability of the Bluebloqs biofilter, the demo can assess and showcase the potential of the technology for the Flanders region.
Figure 1. Design of the system in Aarteselaar generated by Aquafin.
The design of the Bluebloqs system in Aarstelaar is generated by Aquafin, TU Delft and Field Factors and is presented in Figure 1. On the demo site, rainwater from the roof of a service building with a surface of 220m2 is collected in a black rainwater harvesting tank with a volume of 4m3. A peristaltic pump with a flow of 0.5m3/h is used to transfer the rainwater to a biofilter. The rainwater is distributed over the surface of the biofilter by perforated tubes. An overflow pipe in the biofilter prevents flooding in case of filter blockage.
The biofilter has a surface area of 9m2 (3x3), a depth of 1.1m and a slope of 45° (a total volume of 4m3). A minimum biofilter surface area of 9m2 is necessary to guarantee stability and placement of drainage pipes. The biofilter consists of filter sand, topped off with iron coated sand and tree flakes to reduce evaporation.
After biofiltration, the water is collected by a PVC pipe (Ø 110) 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 length of this pipe can be adjusted to investigate the effect of the height of the submerged zone on the efficiency of the biofilter.
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 (Figure 2).
Figure 2. Photo of demo in Aartselaar after completion of the construction works.
Since one of the main objectives of the demo in Aartselaar, in addition to the technical performance of the system is to facilitate interaction with key stakeholders, various interactions with important stakeholders have been initiated, as well as internal working sessions between Aquafin and doctorate students from the TU Delft. In December 2019, a stakeholder workshop was held to present the first results from the extensive monitoring of the system performance, to showcase the potential of the Bluebloqs technology and to discuss the need for and feasibility of such a decentralized circular water system in Flanders. An important debate in this regards was the legislation on the deep infiltration and the outlook on potential changes to this legislation in order to be able to locally provide in the increasing demand for fresh water in long-lasting dry periods.