‘Leaudegem’ is not rocket science, but pure nature

Decentralised water treatment in Ledegem

This summer broke one record after another. With a total of barely 23 millimetres of precipitation, July and August became the driest months since records began in 1833. According to figures from the RMI. Not only Flanders, but the whole of Europe groaned under the heat. In the West Flemish town of Ledegem, they opted for a smart and simple approach to the problem of water shortage.

Dry riverbeds, blocked inland waterways, trucks that had to supply entire regions of France with drinking water, crops scorched all over the fields: 47% of Europe's territory was subject to a drought warning, in 17% the alert threshold was exceeded. Even the biggest climate sceptic must have understood last summer how inextricably linked the fate of the human species is to water. During that same long hot summer, the sanitation project ‘Leaudegem’ was completed in the West Flemish town of Ledegem.

Zoning and implementation plans (VMM)  

In Flanders, all sanitation projects are defined within the zoning and implementation plans of the Flemish Environment Agency (VMM). The discharge conditions are set out in VLAREM Title II and vary according to the zone in which the discharge of domestic wastewater can be accommodated: the central area, the collectively optimised outer area, the collectively optimised outer area, the individually optimised outer area. 

Annually, a zoning plan can be updated to the actual condition. Here, executed (sewerage) projects are taken into account. Everything is then recorded in a Water Implementation Programme (WUP). The ‘Area-wide Implementation Plan’ (GUP) builds on the zoning plan and regulates the implementation and timing of the sanitation projects still to be carried out and their mutual coordination. Priorities and corresponding timing are set. 

Untenable situation

In the case of Sint-Pietersstraat - where discharges into a bay canal via a sewer pipe had been causing odour nuisance for years - this meant that the problem could not be addressed until, say, 12 to 15 years from now. Connecting wastewater to the transport system also involves a very heavy investment burden. This is borne by both the municipalities and Flanders. Indeed, Flanders pays 75 per cent of the sewage project carried out back to the local authorities.

This situation occurs in many places in Flanders: the collectively optimised outlying area still comprises more than 340,000 homes. The challenge that arises is the wastewater transport system from outlying areas to sewage treatment plants (WWTPs). The basic idea among governments was that they would be the last to provide sewerage to the outlying areas, but this is hardly happening and, in any case, far too slowly. There are still 8,500 to 10,000 kilometres of sewers to be built. An unsustainable situation.

Water treatment based on plant systems

Ledegem sticks its neck out and goes for the decentralised solution, backed by a subsidy project. Within the European Blue Deal, the Flemish Ministry of the Environment developed a framework to support demonstrative projects. So innovative, alternative, but at the same time qualitative solutions were sought for wastewater facilities (without sewers) in the outlying area. 

One is local water treatment based on plant systems (helophyte filter). When a restaurant in Kuurne succeeded in using such a helophyte filter to recycle waste water from the kitchen and flush water from the toilets into drinking water, it made the television news. Mobile water purification plants were used to purify wastewater at Flemish and Dutch music festivals. 

Ledegem becomes Leaudegem

And then there is the Leaudegem project, with HelloWater as the lead technical partner. It is all not rocket science, but pure nature. First, all wastewater is collected in a pre-sedimentation tank (step 1). Then the wastewater is injected/pumped into a helophyte filter (step 2). The interplay of plants and bacterial life in the substrate (step 3) already ensures removal rates between 96% and 100% for organic loading, suspended matter and ammonium (BENOR approval efficiency).

Then, an innovative post-purification system called FOSCUBE ensures thorough phosphate removal (step 4). 

A possible disadvantage of plant-based purification is the surface area required. In Ledegem, the helophyte filter was placed directly on the bay canal, so no farmland or other useful land had to be taken. The surface is covered with flowering plants, which even boost biodiversity. The plant itself consists of prefabricated elements that can be easily removed or added. This makes the set-up flexible and scalable as houses are added. CBS Beton from Wielsbeke was approached for those prefab elements.

Cooperation with CBS Concrete

CBS Concrete is the specialist in precast concrete elements for the agriculture and infrastructure market. CBS Concrete products are used in general contracting works, industrial projects, in agriculture and horticulture, silos and agricultural buildings, biogas plants, public procurement and private projects. 

Marc Vandeputte, marketing and communication manager CBS Beton: “Our retaining walls are used to effortlessly bridge height differences at slip roads, gentle slopes, emergency lanes and car parks. Our L-shaped retaining walls (CLF10GS range) are used as modern infrastructure solutions in earthworks, road construction, landscaping and hydraulic engineering. The walls have a smooth finish and meet the highest quality standards for concrete.”

“CBS Concrete is also the first Belgian manufacturer to have a BENOR certificate, which ensures that the retaining walls meet all Belgian and European quality expectations in the sector. For this innovative water treatment system, we supplied 400 kilometres of CLF10GS L retaining walls.”

Wouter Igodt: “The collaboration with CBS Beton came about with an eye on sustainability. Cement has a well-known carbon footprint, which we were keen to see reduced in our water treatment plants. For this, we turned to Resourcefull. They offer a cement alternative based on the use of by-products from the metallurgical and mining sectors. CBS Concrete and Resourcefull joined forces earlier, in an Interreg project: Upcycling Concrete. So that collaboration, including delivery and installation, went super smoothly.”

“Leaudegem, under the slogan: ‘You go faster alone, you go further together’, went for a co-creative collaboration. As a result, the modular-sustainable wastewater treatment plants produced a result we are all proud of.”