Global Waste Management Symposium 2016 Abstract
Model Calibration for Biological Process Modeling of Landfill Leachate
Treatment System
Sara Arabi1, Mehran Andalib1, Christopher Bye2, Andrew Lugowski3
1
Environmental Operating Solutions, Inc. (EOSi), Bourne, MA 02532, [email protected]
2
EnviroSim Associates Ltd., Hamilton, ON, Canada
3
GHD, Waterloo, ON, Canada
1.0 Introduction: Although BioWin® is widely used for municipal and industrial wastewater treatment simulation,
the library of studies demonstrating the experiences of model calibration for a leachate treatment system is relatively
inconspicuous. In order to use simulation packages such as BioWin® for landfill leachate process design, default
parameters in BioWin® needs to be altered to provide valuable information on the performance and process design
of leachate treatment systems. Respirometry and bench scale studies may be required in order to obtain the site
specific stoichiometric and kinetic parameters for model calibration.
2.0 Objectives: Modeling and optimization of a biological leachate treatment process faces two major challenges.
The first one is related to the leachate quality data due to site specific characteristics of landfill leachate and also the
temporal nature of the landfill leachate generation process which significantly impacts the quality. The second
challenge is the calibration of the process models. The goal of this paper is to increase our knowledge and
understanding of the process modeling for landfill leachate using BioWin® simulation package using model
calibration.
3.0 Data Analysis: In this paper, a database was prepared based on leachate characteristics information from 19
landfills in North America to cover young (1-10 years) and medium- strength (10-15 years) leachate in both cold and
warm climates. Soluble and total fractions of organics and nutrients and inorganics are analyzed to obtain the leachate
fractionation characteristics as an input to BioWin® (Table 1). Key stoichiometric and kinetic parameters
information from four landfills are also recorded for sensitivity analysis. Statistical analysis for the data presented in
Table 1, resulted in the fractionation presented in Table 2. Table 3 summarizes the stoichiometric and kinetic
parameters for the landfill leachates used for the modeling effort presented in Section 4.0.
4.0 Model Development and Calibration
Relatively high organics concentration, high non-biodegradable organics and nitrogen fraction, low suspended solids,
and inhibitory impact of leachate on kinetics of biological processes makes it necessary to use a calibrated model for
treatment evaluation or design purposes. Landfill leachate database is considered to verify the predictability of the
BioWin® model with site specific reliable influent characteristics. Changes to the default parameters were made to
minimize the differences between the model predicted and actual leachate characteristics. Table 4 shows an example
of the model input using default characteristics for influent TSS. Leachate generally contains low TSS and using the
default parameters, the model over predicts the influent TSS which subsequently impact the modeled TSS or VSS in
the biological system (an important design consideration). Calibrated model values which results in matching all the
model calculated parameters and actual measurements are presented in Table 5. In case the leachate is inhibitory to
hetrotrophic biomass or nitrifiers, site specific growth parameter biomass-specific nitrification rate should be
considered in the design of a leachate treatment system. The process of model development and calibration for
influent fractions and growth and decay parameters are presented.
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Global Waste Management Symposium 2016 Abstract
Table 1: Summary of Landfill Leachate Characteristics (19 Landfills)
Concentration (mg/L)
Parameter
Ammonia
Biological Oxygen Demand (BOD)
Soluble BOD (SBOD)
Chemical Oxygen Demand
Soluble Chemical Oxygen Demand (SCOD)
Total Kjeldhal Nitrogen (TKN)
Total Phosphorous
Total Suspended Solids (TSS)
Volatile Suspended Solids (VSS)
Range
200 – 1,200
100 – 2,000
50 – 1,600
1,000 – 4,500
900 - 4,000
250 – 1,500
1 - 10
50 - 200
25 - 100
Average
700
1,000
800
3500
3,100
900
3
100
50
Table 2: General Leachate Fractionation
Value
Parameter
SBOD/BOD
SCOD/COD
Ammonia/TKN
0.5 - 0.8
0.9 – 0.7
0.8
Non-biodegradable Influent COD/Total influent COD
0.2 – 0.6
Table 3 – Kinetic and Stiochiometric Parameters used for Modeling
Parameter
Maximum Specific Growth rate , heterotrophs , µ max
Monod half saturation coefficient , KS
Biomass Yield (heterotrophic), YH
Decay Rate bH
Slowly biodegradable substrate XS
Hydrolysis rate constant, Kh
Maximum Specific Growth rate – Ammonia Oxidizers
Unit
d-1
mg COD/L
g COD/g COD
d-1
mg COD/L
d-1
d-1
Default
3.2
5
0.66
0.62
2.1
0.9
Value
2.7 ± 0.71
185 ± 25
0.48 ± 0.03
0.67 ± 0.03
90
0.95 ± 0.05
0.75
Table 4 – Comparison of the Actual vs. Modeled parameters using Default Fractionation
Parameter
COD
TSS
VSS
Actual (mg/L)
3,500
200
100
Modeled using default Fractionation (mg/L)
3,500
1,330
1,100
Table 5 – Calibrated Model Parameters Compared with Default Parameters
Parameter
Fbs- Readily biodegradable
Fus Un- biodegradable soluble
Fup Unbiodegradable particulate
Fzbh Non-poly P heterotrophs
Fxs Slowly biodegradable fraction of COD
Fxsp Non colloidal slowly biodegradable
Fna - Ammonia
Unit
g COD/g tot COD
g COD/g tot COD
g COD/g tot COD
g COD/g COD
g COD/ g tot COD
g COD/g of slowly degradable
g NH3-N/ g TKN
Default
0.160
0.05
0.13
0.02
0.640
0.75
0.66
Value
0.136
0.721
0.018
0.017
0.108
0.008
0.8
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