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WASTE WATER TREATMENT IN WALLONIE. 3,400,000 inhabitants. Guillaume PIROTTE. January, 12th. Contents. First part: General information on waste water treatment in Belgium. Second part: Description of a future waste water treatment plant in Sclessin. General information.
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WASTE WATER TREATMENT IN WALLONIE 3,400,000 inhabitants Guillaume PIROTTE January, 12th
Contents First part: General information on waste water treatment in Belgium Second part: Description of a future waste water treatment plant in Sclessin General information Description of a WWTP
First part: General information History Purification in Belgium Individual waste water treatment History Purification in Belgium General information Description of a WWTP Individual waste water treatment
History • Until 1999: Until 1700, no pipes, no treatments After French revolution of 1789, new laws -> First sewer 1971: First national law 1999: Creation of a Public Company for Water Control History Purification in Belgium Individual waste water treatment General information Description of a WWTP Sewer in Liège
Between 1999 and 2004: Wallon government adopted an investment program -> 898 M€ (~25 billion CZ) between 2000 and 2004 July 2000: Belgium was sanctionned by European Court of Justice • Nowadays: A lot of construction sites have been opened History Purification in Belgium Individual waste water treatment General information Description of a WWTP Location of waste water treatment plants in Wallonie
Purification in Belgium • Context: Everyday, 120 l per capita Only one third is treated… Very far from European goals • Treatment: Classical way Individual approach History Purification in Belgium Individual waste water treatment General information Description of a WWTP
Legal situation, three zones: With a network of sewers -> Customers have to connect Without a network of sewers but it is planned to build it -> Local authority has to decide No network of sewers is planned to be built -> Customers have to construct an individual waste water system before December 2009 History Purification in Belgium Individual waste water treatment General information Description of a WWTP
Individual waste water treatment • The classical system: Pretreatment: Septic tank Treatment: Aerobic bacteria Final evacuation: To a pipe or directly to the soil • The lagoon’s system: Septic tank Waste water flows different basins with special aquatic plants Afterwards, water can filtrate to the ground History Purification in Belgium Individual waste water treatment General information Description of a WWTP
Dry toilets: Make compost with faeces instead of evacuating them by water -> Quite unusual and ask a lot of efforts • Economic standpoint: Classical system: 3,000 to 5,000 € (84,000 to 140,000 CZ) Lagoon system: 5,000 to 8,000 € (140,000 to 225,000 CZ) Dry toilets: 1,000 to 1,500 € (28,000 to 42,000 CZ) History Purification in Belgium Individual waste water treatment General information Description of a WWTP
Second part: Description of a WWTP Context Technical features Water treatment Sludge treatment Context Technical features General information Description of a WWTP Water treatment Sludge treatment
Context • Place: Sclessin • Construction: From Mey 2006 to January 2009 • Cost: 51.5 M€ (1.4 billion CZ) Context Technical features Water treatment Sludge treatment General information Description of a WWTP Sclessin
Technical features • Maximum inlet: Nominal loading: 200,000 EI Day-to-day volume: 40,712 m³/d Maximum flow: 6.463 m³/s Day-to-day BOD loading: 10,800 kgO2/d Day-to-day COD loading: 22,610 kgO2/d Day-to-day azote loading: 2,084 kg/d Context Technical features Water treatment Sludge treatment Day-to-day phosphore loading: 402 kg/d General information Description of a WWTP
Outlet demand: Maximum BOD: 25 mgO2/l Maximum COD: 125 mgO2/l Maximum waterborne particles: 35 mg/l Maximum sedimentation matter concentration: 0,5 ml/l Maximum fat and oil concentration: 3 mg/l Maximum azote concentration: 10 mg/l Maximum phosphore concentration: 1 mg/l Context Technical features Water treatment Sludge treatment Maximum detergent concentration: 3 mg/l General information Description of a WWTP
Water treatment • Mechanical treatment: Pump station with three bar screens (40 mm gap) Six other bar screens (10 mm gap) Inlet flow measure Six longitudinal basins which remove sand, oil and fats Three circular covered settlers -> Solid matters decay in an anaerobic way -> Primary sludge Context Technical features Water treatment Sludge treatment General information Description of a WWTP Bar screens Venturi system Longitudinal basin
Biological treatment: Three big rectangular aerated and mixed basins -> Flocs are formed Three secondary clarifiers -> Clean water is separated Context Technical features Water treatment Sludge treatment Secondary clarifier Activation tanks General information Description of a WWTP
Sludge treatment Sludge is purged Sludge is obtained thicker Sludge is dewatered -> Reducing transport cost -> Dry enough for final storage Context Technical features Water treatment Sludge treatment General information Description of a WWTP
Conclusion • Total capacity: Evolved from 1,800,000 in 2000 to 2,600,000 EI in 2004 660,000 EI are planned to be added in the future • People do just begin to understand…
THANk YOU FOR YOUR ATTENTION Guillaume PIROTTE January, 12th