Electricity produced by the force .com of the Vesdre River! debie www. The plant at the Vesdre Complex includes a hydro-electric power station. This power station enables Société wallone des eaux to produce green electricity. As part of project VEGI, the Eupen plant has been equipped with four new turbines. Altogether the turbines produce 5 million kWh (kilowatt hours) per year, equivalent to the annual consumption of 1,500 households. This electricity is mainly used by SWDE for supplying its own facilities, thus making large energy savings by using electricity that is completely non- polluting, since it produces no CO2 emissions. This also ensures that the purification plant’s pumps are continually supplied with electricity. Why add a nanofiltration stage to the water purification process? Société wallone des eaux is committed to › formation of a biofilm, a natural occurrence molecules that result from the injection of Eupen purification plant supplying high-quality water. This is why it in water networks. This biofilm might lime and carbonic acid that is used to make was essential to improve the operation of come loose unexpectedly according to fenland water non-corrosive to metal water (La Vesdre Complex) the Vesdre treatment plant in Eupen and the variations in flow or the level of organic pipes. the Gileppe plant in Stembert, in order to matter in the water. The consequence of this effectively remove naturally occurring and is cloudy and discoloured water, but it is not It is also necessary, therefore, to inject sodium humic organic matter (components that harmful to health. hypochlorite after the nanofiltration stage and are naturally present in the region’s soil and to replace the injection of lime and carbonic Modernised facilities to meet the new European regulations water). In order to find the best solution all existing acid with calcite filter treatment. techniques have been tested at a pilot unit. It The start of project VEGI make improvements to meet the increasingly Insufficient removal of these types of organic was found that the most effective means was Nanofiltration is a technique that has already (Vesdre-Gileppe): exacting standards relating to water quality. substances leads to the following problems: to supplement the water treatment process been implemented by SWDE at the Gaurain- The plant treats 45,000m3 of water for drink- with a filtration process using nanofiltration Ramecroix plant in Tournai, where 8,000m3 The water that comes from the Vesdre and ing every day. › formation of THMs (trihalomethanes), which membranes. of water per day is purified using this Gileppe dams supplies a large number of multiply along water pipes and fail to meet technique. towns in the regions of Eupen, Verviers and Work began in 2006 and nanofiltration, the European legislation reducing the permit- These membranes, which can be compared le Pays de Herve, as well as almost the entire stage that has been newly added to the wa- ted level of THMs in water from 150 to 100 to nylon stockings, are full of pores a millionth Liège area, via a pipeline liniking Eupen and ter treatment process, has been operational micrograms/litre. THMs are chlorinated by- of a millimetre in size which do not let organic Grâce Hollogne. since March 2009. products that appear when organic matter matter through. in the final stages of biodegradation (“humic In order to meet future European quality The total cost of implementing the whole matter”) reacts with the chlorine needed to They are, however, sensitive to chlorine and standards for water, in particular water de- project VEGI is more than €42 million and is treat the water. they do not stop the calcium bicarbonate riving from surface waters, which are more being paid for by Société wallone des eaux. sensitive to pollutants, Société wallone des eaux (SWDE) has started major modernisa- The nanofiltration capacity of the two plants tion work at its Stembert (Gileppe) and Eupen is now around 110,000m³ per day, one of (Vesdre) purification plants. the largest in Europe, behind that of Mery- sur-Oise near Neuilly-sur-Marne, in the Paris The plant at the Vesdre Complex has made region. Our clients water from the Eupen dam safe to drink since 1951. Since then it has been necessary to Water is distributed from the treatment plants in Limbourg, Chaudfontaine, Flémalle, Fléron, Eupen and Stembert to towns in Liège province, Grâce-Hollogne, Saint-Nicolas and Esneux). which may be served by Societe wallone des eaux (Verviers, Aubel, Soumagne, Baelen, Dal- In total, more than 400,000 inhabitants use hem, Eupen, Thimister-Clermont, Plombières, water from the two treatment plants in the Ver- Financial help from the EIB: Raeren, Welkenraedt, Herve, Jalhay, Lontzen, viers region every day,for drinking, washing and Spa, Amay, Engis, Dison, Neupré, Olne, Pepin- cooking. On 8 December 2006 at Société wallone des eaux’s headquarters This translated specifically into the modernisation works carried out at ster) or the water is sold on to other water dis- in Verviers, Philippe Maystadt, President of the European Investment the Vesdre Complex in Eupen and the Gileppe Complex in Stembert, as tributors (the towns of Liège, Seraing, Theux, Bank, in the presence of the Supervisory Minister, signed a loan agree- well as other works that have been carried out to increase the capacity ment for the sum of €125 million. The aim of this financial agreement and effectiveness of water production. was to enable SWDE to accomplish its €265 million investment pro- gramme for the 2006-2008 period. Some essential investments to improve the quality of our service and of the water from your tap. Supported by paper friendly on environmentally Printed the European Investment Bank www.swde.be Surface waters Why use calcite filters? Water treated at the Vesdre plant Fenland water is acidic. This is why it comes from the Eupen dam. is essential to replenish the minerals This is surface water in it so that it does not corrode the (rather than ground water), pipes. This happens in two stages: which only represents 20% first of all the water is acidified by of all water resources in Wallonia. q. injecting carbonic acid (CO2) Most countries in the world, It is then filtered through a 2m layer however, of limestone. In passing through this use mainly surface waters. bed the water picks up calcium and Every year, 16 million m3 of water becomes a little harder. This means is taken from the Eupen dam. that it is no longer corrosive enough to damage the water pipes; instead, a slight deposit is left behind on the pipes that gives them additional protection! Purification plant: how it works During the next stage the water passes through 23 sand filters 7, Before returning to the reservoirs, which have a total capacity of composed of a 1m layer of graded sand, positioned above a filtra- 50,000m3 , the water goes through 5 calcite filtersw . These filters Water coagulation and flocculation tion floor which is full of minute holes. Due to the filtration qualities are washed in the same way as the sand filters, except the water of the sand, aluminium, iron and manganese particles are retained used for washing is not re-used. The first stage is where water passes through a series of treatments to in the sand layer. clarify the water. The first compartment in this process is the coagulator 1. During the purification process the water is very lightly chlorinated A coagulant is injected 2, which destabilises the suspended particles. When these filters become clogged, they are washed. First the sand three times to guarantee its bacteriological quality during storage is decompacted by pumping air under the filtration floor8 . Next, fil- and transportation. To do this, sodium hypochlorite is injected Then the water passes into one or more vats 3 where a flocculent 4 is tered water is forced through the floor in order to wash the filter layer. into the water before it is passed through the sand and calcite filters. added, which leads the suspended particles to clump together, to form This water is then drained into the dirty water reservoir 9. Finally, the purified water is distributed to Société wallone des eaux’s sludge. clients. The water is separated from the sludge in a decantation system 5. Nanofiltration, chlorination and storage of purified water When the maximum level of sludge is reached, the excess sludge is drained into ponds 6 where it will undergo natural thickening before be- Eighty per cent of the water then goes through a nanofiltration ing treated and removed by a specialist firm. stage (the remaining 20% goes directly to the next stage). It is then pumped through one of the five nanofiltration lines 0, through membranes with nanometre-scale pores. This stage ensures that all particles smaller than this size are retained, such as organic matter or calcium..