Innovative techniques to reduce sludge production and disposal by 203x8y1

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									Innovative techniques to reduce sludge
production and disposal

     Marjoleine Weemaes
     Greet De Gueldre
     Aquafin NV




                                         1
Sludge production Aquafin

   2002: 284.200 tons / 85.015 tds
   mean spec. sludge prod.: 68 g ds/PE.d, 1.66 g ds/g BOD removed
   prognosis 2010: 310.000 tons / 90.000 tds
   costs (2002):  25. 000.000 €
        disposal
        transport
        chemicals
        environmental taxes
        dewatering by a third party
        (sand and grid)




                                                                     2
Reduction sludge production: innovative techniques




                               Optimalisation digestion
                               • Process parameters
                               • Pretreatment


Sludge mineralisation
• Degrémont Biolysis




                         Increasing
                         dewaterability

                         • Deshydroplus

                                                          3
Optimalisation dewaterability: DHp
        Sludge structure: 40% Extracellular Polymeric Substances
         (EPS)
             gelly 3D-structure, retains sludge water
             destruction EPS  increased dewaterability


        Treatment:
             Thermal hydrolysis
             Thermochemical (acid or caustic thermal hydrolysis)
             Oxidative (Fenton)
             DHp-treatment: addition DHp reagens
                 no temperature-, pressure-, pH-correction needed




        Lab scale performance DHp-treatment:
             increase of 12,7 ± 1 % DS in dewatered sludge


        Upscale to pilot & full scale




                                                                     4
Aërobic mineralisation: Biolysis E (Degrémont)




                 Hydrolysis



      Hydrolysis: hydrolysis/desintintegration of settled sludge by
       ‘aggressive’ conditions
                   release of biodegradable intracellular material
                      metabolised in aeration basin (cryptic growth)


              chemical hydrolysis (acid, base, …)
              mechanical desintegration
              thermal hydrolysis - thermophilic hydrolysis (biological)
              ozone / chlorination


                                                                           5
    Aërobic mineralisation: Biolysis E (Degrémont)
   Bacillus stearothermophilus (55-70°C)  sludge hydrolysis
   Shinko Pantec S-TE process®: partial or complete reduction of excess
    sludge

   Europe: commercialised by Degrémont: Biolysis E, Verberie, 3000 PE




                                                                           6
Aërobic mineralisation: Biolysis E




                                      7
Aërobic mineralisation: Biolysis E: Pilot Verberie
(3000 PE)




                                                      8
    Aërobic mineralisation: Biolysis E (Degrémont)
   Bacillus stearothermophilus (55-70°C)  sludge hydrolysis
   Shinko Pantec S-TE process®: partial or complete reduction of excess
    sludge

   Europe: commercialised by Degrémont: Biolysis E, Verberie, 3000 IE

   Results:
         45-80% reduction sludge production (depending on amount of treated sludge)
         slight increase effluent SS, COD, P
         improvement SVI
         compatible with N-DN
         suitable for treatment plants of 20.000-400.000 PE


                       Pilot tests in Houthalen (100 l/h)


                                                                                       9
Sludge digestion: view of Aquafin

                Sludge reduction
               Energy production                 High capital costs
        Increased dewaterability                 Load sludge waters
           Hygienisation (odours)                Removal primary settling tanks
       Green Current Certificates

                      Switchover to sludge digestion


      Renovations (3 realised, 3 planned)
      Introduction thickening tables : existing digestion capacity  70%
      Construction of additional buffering capacity for external sludges
      Profitable use of biogas:
          gasengines

          energy production for sludge dryers




                                                                                  10
 Sludge digestion: realizations of the passed 10 years


          1994                       2003                       2006
8 digesters operational     11 digesters operational   17 digesters operational
        30.570 m3                 37.495 m3                  58.934 m3
        11.000 tds                30.220 tds                 53.000 tds



        Biogas production (2003)
            8 gasengines: 1.017.272 m biogas  1.831.089 kWh
                                      3

            heat energy for sludge dryers: 2.261.531 m ~ 52.015 GJ
                                                       3

            green current certificates




         New developments: research pretreatment techniques




                                                                                  11
Sludge digestion: Green Current Certificates (GCC)


      Electricity suppliers  3% ‘green’ energy

             penalty:     100 €/MWh in 2003

                           125 €/MWh in 2004

      Generation of green current  1 GCC/MWh

      Expected market value: 125 €/GCC in 2004




                                                     12
Reduction of sludge production and disposal

         Interfering in
              sludge production (activated sludge treatment)
              sludge stabilisation (digestion)
              sludge dewatering

         Actual projects
              development new techniques: improvement of sludge
               dewaterability: DHp
              evaluation innovative ‘marketable’ techniques: reduction of
               sludge production: Biolysis E (Degrémont)
              optimalisation known technologies: expansion and optimalisation
               of digestion technology, evaluation of new developments




                                                                                 13

								
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