AEROBIC AND ANEROBIC METABOLISM OF GLUCOSE AND CELLULOSE

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AEROBIC AND ANEROBIC METABOLISM OF GLUCOSE AND
CELLULOSE

• John M Owens PhD
• Biological Engineering Seminar

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Objective

• To determine the extent and rate of aerobic and
  anaerobic methanogenic decomposition of organic
  matter

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Aerobic and Anaerobic Metabolism of Glucose

• Aerobic, Biochemical Oxygen Demand (BOD)
• C6H12O6 O2 ? 6CO2 6H2O
• Anerobic, Biocmemical Methane Potential (BMP)
• C6H12O6 ? 6CH4 6 CO2

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Examples of Aerobic Metabolism

• humans and other animals
• respiration in plants
• aerobic bacteria in rivers, lakes, soil

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Principles of BOD Test

• Mix broad spectrum inoculum (activated sludge)
  and substrate (or waste)
• Aerobic environment
• Absorb CO2 with base
• Measure oxygen uptake (reduction in oxygen
  concentration or pressure)

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BOD Equation

• BODt BODult (1 e-kt)
• Where
• BODult is the ulitmate BOD or the BOD at
  infinite time, t.
• BODt is the BOD at time, t
• K is the first order rate constant.

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BOD Plots
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Principal Reactions Of Balanced Biomethanogenesis
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Natural Sources Of Atmospheric Methane
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Anthropogenic Sources Of Atmospheric Methane
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Rationale

• Determine organic matter (volatile solids VS
  reduction)
• Determine methane production potential
• Natural environments
• Industrial environments (waste treatment, energy
  from biomass)
• Conversion efficiencies and kinetics

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Approach

• Excess broad spectrum inoculum of known
  performance
• Anaerobic conditions
• Non-limiting nutrients
• Mid-range temperature (35oC)
• Non-inhibitory substrate levels
• Buffered against pH changes

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BMP Inoculum Digester
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Performance of BMP Inoculum Digester

• loading rate, 1.6 g VS/L/d
• retention time, 20 d
• biogas methane content, 57
• methane yield, 0.33 L/g VS
• methane production rate, 0.53 L/L/d
• pH, 7.3
• volatile acids, 155 mg/L

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Setup Steps

• Boil dilution DI water cool to room temp. while
  outgassing with N2 continue to outgas during
  setup
• Add 20 by volume inoculum
• Add nutrients, sodium sulfide, and bicarbonate
• Add substrate and inoculated medium to BMP
  bottles while outgassing medium and bottleso
• Stopper bottles and incubate at 35oC

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BMP Apparatus
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BMPS of Typical Feedstocks
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Variability of Sorghum
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NASA BMP Data (3)
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Biochemical Methane Potential Data, 30 days
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Measurements

• Total solids (105oC)and volatile solids (500oC)
  of substrate
• pH of medium
• Gas production and methane content (daily for
  first week then less frequently until gas
  production is negligible)
• pH and volatile solids of each bottle at
  completion

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Data Presentation

• Table of raw data
• Spread calculation of accumulative methane yield
  (L/g VS added)
• Plots of accumulative methane yield versus time
  for control, glucose, and cellulose
• Linearized plots for glucose and cellulose and
  rate constants

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Typical Samples
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Sample Weights
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Barometric Pressure on Gas Sampling Dates
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Raw Data for One Bottle
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Sample Calculation of Methane Production
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Sample Final Calculation of Methane Yield
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Plot of Data
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Linearization of Data
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Assignment

• When 10/21/02
• Room 148 (5-7 p.m.)
• Contact person, Patrick Haley
• View setup apparatus
• Measure gas production and composition in bottles
• Write report

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Report

• Title
• Authors
• Objective
• Rationale
• Methods
• Results
• Discussion
• Answers to Questions