Biodegradation and gas formation in landfills by naa14009

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									                    Institute of Biochemical Engineering
                    TU Braunschweig




Biodegradation and gas formation in landfills


                     Research group:
      Nicole Fischer, Irena Knappik, Thomas Reichel,
             Detlev Rasch, Andreas Haarstrick
                                                                    Landfill gas
There will always be uncertainties:
  Data acquisition, data access                                     Formation
  (spatial distribution, time dependence)
  Process knowledge                                              Biodegradation
                                                                   Bioactivity

                                                                      Impact
Detailed (complex) models
versus simple 1.order solutions:
                                                 Interaction with          Waste composition
  Use of methane gas (long-term prediction)      waste material
                                                                           Heterogeneities
  Risk assessment, monitoring, CDM
                                                 Reaction conditions
  Bioreactor landfills                                                     Stoichiometry
                                                 Transport

Questions:
  How much do we know about biodegradation processes?
  Number of input parameter for mechanistic model; data uncertainties?
  How important are intermediate by-products?
  How important is the waste characteristic (composition, particle properties, …)?
  Can we scale-up to landfill size?


                                   Introductory note
                                                                                                             Rgrowth
                                        Solid organic waste                                                  Rhydrolysis
                                 (carbohydrates , fats/lipids , proteins )
                                 (                    /
                                                                                                             Rdeath
Extracellular                                                                          Extracellular
enzymes
                                           HYDROLYSIS                                  enzymes               Racids
                            Easily hydrolyzable          Slowly hydrolyzable                                 Rgases

                                Low-molecular soluble organic
                        compounds (e.g. glucose,fatty acids, amino acids)
                                                                                                             Oxidized
                                                                                                             electron
     Biomass                                                                           Biomass
                                           Inactivation ,                                                    acceptors
      growth                                                                            growth
                                              death
ACIDOGENESIS                                                                     ACETOGENESIS
                                                                                                              Respiratory
                                                                                                             Respiratory
Organic acids                                                                                                   chain
                                          Biomass                ACETO -          Acetic
(e.g., butyric acid ,                                                                            CO 2, H 2
                                           growth                GENESIS          acid
propionic acid ,
lactate )
NH 3      H2 , CO 2                                                          Biomass
                                                                              growth           Biomass       Reduced
                                                                                                growth       species
                                                       METHANOGENESIS
                                 CH 4 , CO 2
                                                       METHANOGENESIS



                           Pathways of anaerobic degradation
                       dS c    λ ⋅ µ max                               
Degradation                 =−           ( X s + X im ) ⋅  S c ⋅ S e 
                                                          K +S K +S                                                 ( 6)
                                                                                                          diluted organic substrate
                        dt      YX / S                     Sc  c Se  e 




                       dS e       λ ⋅ µ max                              
                            =−f ⋅           ( X s + X im ) ⋅  S c ⋅ Se 
                                                             K +S K +S                                              (7)
                                                                                                                 electron acceptor
                        dt         YX / S                     Sc  c Se e 



Growth                 dX s                      Sc      Se 
                                                K +S K +S 
                            = λ ⋅ µ max ⋅ X s ⋅       ⋅                                                            (8)
                                                                                                              suspended biomass
                        dt                       Sc c   Se  e 




                       dX im                       Sc      Se 
                                                  K +S K +S 
                             = λ ⋅ µ max ⋅ X im ⋅       ⋅                                                         (9)
                                                                                                                immobile biomass
                        dt                         Sc c   Se  e 



Inhibition            dX s , (im )                                      Sc         Se 
              a)                                                   K +S +S /K K +S 
                                      = λ ⋅ µ max ⋅ X s , ( im ) ⋅         2
                                                                                ⋅                             substrate inhibition
                                                                                                                 (10)
                           dt                                       Sc c   c I   Se   e 




                     dX s , ( im )                                 Sc     KI ,P     Se 
              b)                     = λ ⋅ µ max ⋅ X s , ( im ) ⋅       ⋅       ⋅                              (11)
                                                                                                                 product inhibition
                         dt                                       K +S K +P K +S 
                                                                   Sc c   I ,P    Se   e 


Endogeneous
                     dX im
                     dX ss,,((im ))                                S c Sc S e                 S    
metabolism    c ))
              a                     = λ ⋅s ,µim ) ⋅  λ ⋅s ,µ max⋅ 
                                      X ( max  X ( im ) ⋅
                                                    ⋅                           ⋅          ⋅− b  e            (14) )   cell decay
                       dt
                       dt                                          K Sc + S c +K Se /+K e K  + S 
                                                                                  Sc SI         
                                                                                                                  (12
                                                                    Sc       c                Se   e 



                     dS cs , ( im ) λ ⋅ µ max                                          S
                            = − = λ ⋅ µ maxX sX− , (X im⋅)⋅  S c c ⋅ ⋅ K I e ⋅ − me 
                                              ( ⋅ s im )   S
                     dX                                                      S
              d)                                            K Sc + S c KK Se S S e K + S 
              b)                                                                                              (15) ) maintenance
                                                                                                                  (13
                      dtdt           YX / S                K Sc + S c    I + c
                                                                               +      Se  e 



              Degradation and growth kinetics
Sulphate reduction                           Influence of Sulphate

SO42- + 4 H2 ↔ H2S + 2 H2O + 2 OH-          ∆G‘R = -154 kJ/mol
SO42- + CH3COOH ↔ H2S + 2 HCO3-             ∆G‘R = -43 kJ/mol
                                                                     Thermodynamic
Methane formation                                                    aspects
CO2 + 4 H2 ↔ CH4 + 2 H2O                    ∆G‘R = -136 kJ/mol
CH3COOH ↔ CH4 + CO2                         ∆G‘R = -29 kJ/mol


Acetogenesis                                        Interspecies hydrogen transfer

6 CH2O + 2 H2O ↔ 2 CH3COOH + 4 H2 + 2 CO2            ∆G‘R =   +116 kJ/mol
                                                                           - 20 kJ/mol
CH3CH2OH + H2O ↔ CH3COOH + 2 H2                      ∆G‘R =      +10 kJ/mol
                                                                          - 126 kJ/mol
CH3CH2COOH + 2 H2O ↔ CH3COOH + 3 H2 + CO2            ∆G‘R =      +76 kJ/mol
                                                                          - 60 kJ/mol
CH3CH2CH2COOH + 2 H2O ↔ CH3COOH + 4 H2 + CO2         ∆G‘R = +104 kJ/mol
                                                                           - 32 kJ/mol


Methanogenesis
CO2 + 4 H2 ↔ CH4 + 2 H2O                             ∆G‘R = -136 kJ/mol


                 Impact of Sulphate and Hydrogen
                               Waste characterization and stoichiometry


Waste         Group of            Specific mass            Percentage of elements of        Specific mass proportion of
character     waste               proportion               organic dry mass                 elements of organic dry mass
              material             (kg/kgwaste)               (%)     (after EHRIG, 1980)     (nTM,i νi,j ) / 100   (kg/kgdry waste)

               i                   ni,wet         ni,dry    ν i,C   νi,H    ν i,O    νi,N    C           H            O         N
              Kitchen waste,
Readily       garden waste,         83,6          82,2     41,7     5,7    27,5     2,8     34,28       4,68         22,6       2,3
degradable    textiles
              Paper, wood,
                                     1,1           0,9     45,4     6,1    42,1     0,3     0,41       0,055         0,38     0,003
              textiles
Slowly
degradable    Plastics,
              paper                 15,1          14,8     60,0     8,6    19,3     1,0     8,88        1,27         2,86      0,15

              Metals, glas,
inert         tyres, hard                          2,1
              plastics


                                                                     Sum, kg/kgwaste        43,57       6,005       25,84     2,453

                                 Specific mol proportion of element, mol/kgwaste            36,30       60,00       16,15      1,75

                                                                    Element formula         C36          H60        O16         N2




             Element analysis from waste characterization
Initial organic waste content (% w/w):
    readily, slowly degradable, inert



                                             Element formula CcHhOoNn of organic matter
   Hydrolysis constant
                                   60
     kh,readily, kh,slowly         58                           H
                                   56
                                   54
                                   52
                                   50                                          C24-36H 40-60O10-16N1-2   H40-60
                                   48
                                   46
                                   44
                                   42
                                   40
                             mol number
                             Molzahl (Mol)



                                   38            C
  From waste characterization:     36
                                   34
  C24-36H40-60O10-16N1-2           32
                                   30                                                                    C24-36
                                   28
                                   26
                                   24
  From chemical analysis of 24 samples:
                                   22
                                                                                O
                                   20
  (hard plastic and textile pieces greater than 12 mm
                                   18                   were sorted out)
                                   16
                                   14
  Upper values:                    12 C33H53O22N                                                         O10-16
                                   10
  Lower values:                     8 C20H31O15N                                                   N
  Averaged element formula: 6 C27H43O19N
                                    4
                                    2                                                                    N1-2
                                    0
                                               1               2                 3                 4
                                                                    element
                                                                    Elemente


Element analysis of samples from different landfill locations
      Change of waste particle properties after 3 month of degradation



                16
                14
                12
  load [mg/g]




                10
                 8
                 6
                 4
                 2
                 0
                     0         1000       2000        3000       4000        5000
                                 concentration at equilibrium [mg/L]
                         Hexanol after degradation   Ethanol after degradation
                         Hexanol                     Ethanol




Interaction and change of waste particle properties
Data-based models (black box):
… formally describe the process behaviour without
  attempting to define the physical or biological basis ...
          ► Polynom models, regression modells
                                                              Knowlegde fusion

Rule-based models:
… use knowledge about the process extracted from               Hybrid modelling
  experience of process experts …
          ► Linguistically in terms of: if … then … rules      … combines all
          ► Fuzzy expressions                                    advantages
                                                                 of using data
                                                                 and
First-principle models:
                                                                 a priori knowledge
… use mathematical models based on purely physical             …
  mechanisms …
          ► Mass balance
          ► Monod




                            Hybrid modelling
     Comparison
     Comparison
      between
      between
       model
       model
        and
        and
       reality
       reality




Hybrid modelling
                             4                                                                          4


  gas formation rate [L/d]




                                                                             gas formation rate [L/d]
                                                methane (exp)                                                               carbon dioxide (exp)
                             3                                                                          3
                                                methane (sim)                                                               carbon dioxide (sim)

                                                methane (Sim+ANN)                                                           CO2 (Sim+ANN)
                             2                                                                          2


                             1                                                                          1


                             0                                                                          0
                                 0   20   40      60          80       100                                  0   20    40      60        80         100
                                           time [d]                                                                    time [d]


                             4
gas formation rate [L/d]




                                                 total gas(exp)
                             3                                                                          Anaerobic solid waste reactor
                                                 total gas (sim)
                                                                                                        Recirculated and saturated
                             2                   total gas (Sim+ANN)
                                                                                                        TC = 7,8 kgC (10 a old waste)

                             1


                             0
                                 0   20   40      60          80       100
                                           time [d]

                                                  Hybrid modelling
                 15
                          Experiment                 Prediction
                                                                                       Model accuracy related to
                 12                                                                    available experimental data
                                                                      CH4
   Gas [L/kgC]




                 9


                 6
                                                                      CO2
                 3

                             Validation                                            Anaerobic solid waste reactor (TUB)
                 0
                                                                                   Recirculated and saturated
                      0        200         400       600       800      1000
                                             Time [d]
                                                                                   TC = 16,8 kgC (10 a old waste)


               500          Experiment                   Prediction

               400                                                    CH4
Gas [L/kgC ]




               300                                                    CO2

               200

               100                   Validation
                                                                                   Consolidated Anaerobic Reactor (UoS)
                 0
                      0        400         800       1200     1600          2000
                                                                                   Recirculated and saturated
                                                                                   TC = 11.5 kgC (fresh waste)
                                              Time [d]


                                                            Hybrid modelling
                    landfill scale, macroscale (1 – 100 m)

                                                                        mesoscale (1 – 10 cm)

Different conceptual approaches for modelling growth, substrate degradation, and
Different conceptual approaches for modelling growth, substrate degradation, and
biologically reacting solute transport in the microscale and sub-microscale area:
biologically reacting solute transport in the microscale and sub-microscale area:

• Macroscopic approach
• Macroscopic approach                                    gas              solid
  (assumes no biomass configuration and absence of diffusional resistance)
  (assumes no biomass configuration and absence of diffusional resistance)

• Discrete microcolony approach
• Discrete microcolony approach
  (cells grow in small microcolonies attached to waste particle surfaces)
  (cells grow in small microcolonies attached to waste particle surfaces)
             sub-microscale (10 – 100 m)
• Biolfilm approach
• Biolfilm approach
  (continuous layers that cover the waste particle surfaces)
  (continuous layers that cover the waste particle surfaces)
     biofilm
• Two component cell approach
• Two component cell approach    biofilm    solid
  (growth is limited by sorption processes which are more pronounced at low organic load and
   (growth is limited by sorption processes which are more pronounced at low organic load and
                                                                         liquid
  desorption is much slower than microbial degradation)
   desorption is much slower than microbial degradation)



                                 liquid       microscale (1 – 10 mm)


                               Consideration of scale
Final notes

-   Consideration of biochemical / microbiological processes are needed
-   This is especially true for controlling landfill bioreactors
-   Identification of processes that prevail on different scales
-   Model uncertainties may be handled by hybrid modell approaches
  Mechanistic model + artificial neural network (ANN)


                                                                                           (MM)
Environmental variables


                                                                 DOC
 (direct measurements)


                                                 75 % for training
                                                                 Ac
 ∆rCO2 = rCO2, sim – rCO2, exp
        TC
                                Mechanistic model
                                      25 % for validation
                                   of known
                                                          rCH4
                                                                  rCO2                ∫       Output:
                pH             Monod-type kinetics % for training                              state
                                                75
 ∆rCH4 = r CH4, sim – rCH4, exp
                    T                                       Compensation                     variables
            W                         25 % for validation
                                          ∆rexp,mod 2 rCH 4 = rCH 4 + ∆rCH 4 ,val
                                                                                      ∫
                                             CH 4 ,CO
                                                        *
                              Ac
   T
  pH                                 DOC               rCO2 = rCO2 + ∆rCO2 ,val
                                                        *

                      ANNCH4 [6,3,1]      tr            ∆rCO2, tr , ∆rCH4, tr              (HM)
  TC
   W                                                  ∆rCH4,val
                                                                                     Mass
                                ANN
                      ANNCO2 [6,3,1] CH4 [6,3,1],
DOC                                      val            ∆rCO2, , ∆rCH4, val         balances
                                                                                        compensation
  Ac                             ANN [6,3,1]          ∆rCO2,val val
                                       CO2



                                     Kinetics




                                   Hybrid modelling
                   Influence of Sulfate and Dihydrogen Sulfide - Experimental Data


                                     8                                                                                                        0,7
maximum specific methane formation
maximum specific methane formation




                                                                                         T: 55 °C                                                                                                T: 55 °C




                                                                                                       specific methane formation rate rate
                                     7                                                                                                        0,6
                                                                                         T: 35 °C                                                                                                T: 35 °C
                                     6
        [g / /kg-/ organic waste]




                                                                                                                                              0,5




                                                                                                               [g[g kg- organic waste]
                                                                                                                  / / d / kg-oW]
         [g d kg-oW]




                                     5
                                                                                                                                              0,4




                                                                                                        specific methane
                                     4
                                                                                                                                              0,3
                                     3                                                                                                                                     ∧ 531 mg/L-H S
                                                                                                                                                                           =           2
                                                                                                                                              0,2
                                     2                                                                                                                  ∧ 195 mg/L-H S            ∧
                                                                                                                                                        =           2
                                                                                                                                                                                  = 567 mg/L-H 2 S
                                     1                                                                                                        0,1                                           ∧ 865 mg/L-H S
                                                                                                                                                                                            =           2


                                     0                                                                                                        0,0
                                         0   500       1000      1500      2000      2500       3000                                                0        500    1000      1500     2000     2500    3000
          a)                                       initial sulfate conentration [mg/L]                            b)                                           initial sulfate concentration [mg/L]




                                                            Effect of sulfate and temperature on the:
                                                            a) the maximum specific methane formation
                                                            b) formation specific methane formation rate
        Biological                                               Time dependent
       processes,                               &
                                                S                change of organic
 local reaction network                                          material and emissions


                                                                 Quantity of organic
                                      S1 , S 2 , S3 , ..., S n   material, substrates, …


         Model
                                     &
                                     Q = f ( X , S ,...)         Heat
                                                                 production
     dS
        = M ⋅ r + q(S )
              & &
     dt
                                     η = f ( X , S ,...)
                                     &                           Change of fluid
                                                                 properties (leachate)


                                                                 Structural change
                                        Φ = f (X )
                                        &                        of waste matrix
    Reaction conditions                                          (porosity)

r = f ( S , pH , T , w,...)
&
                                  Vwaste = f ( ρ waste )
                                   &                             Influence on
                                                                 mechanical behaviour



                              Reaction network
                                                                     pH factor
                                                               Temperature
                                                               water content factor
                                                                Moist factor
                             Kinetics:                 1 1.0
                                                      1.0              m ax,1     m ax,2     b
                             • Monod                 0.8 0.8
                                                      0.8
                                                     0.6 0.6




                                              fH2O
                                                fTemp
                                             fH2O
                                                      0.6
                             • Multi-substrate (Mankad / Bungay)




                                                fpH
                                                     0.4 0.4
                                                      0.4
                             • Hydrolysis            0.2 0.2
                                                      0.2
                                               0.00.0
                     Stoichiometric            0
                              • Inhibition                4
                                                  0 2 0 20 20 40 6 40608   6010
                                                                            80              12
                                                                                           100
                                                                                           80
                       coefficient
                                ν                       moist content (m/m -
                                                        water content (m/m-%)%)
                                                                   pH
                                Growth, non-growth coupledTemperature (°C)
                       matrix•(νij)                             (Pirt)
                                                                                Mass transfer
    dS/dt = r ⋅ M ⋅ fTemp⋅ fpH ⋅ fH2O ⋅ Bf + q
                                                           Bio-availability factor
                                                                 (0 ... 1)
 Change of         Temp. factor     pH factor Water content factor
concentration        (0 ... 1)       (0 ... 1)      (0 ... 1)




                Consideration of environmental factors

								
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