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Laboratory Scale Anaerobic Digesters- Theory and Operation. By: Zachary Bryan Scott Department of Civil and Environmental Engineering University of California, Irvine. Motivation. Wastewater Treatment : Aerobic Biological Treatment of Wastewater Cleans wastewaters
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Laboratory Scale Anaerobic Digesters-Theory and Operation By: Zachary Bryan Scott Department of Civil and Environmental EngineeringUniversity of California, Irvine
Motivation • Wastewater Treatment: • Aerobic Biological Treatment of Wastewater • Cleans wastewaters • Generates Biomass (0.4g VSS/ g COD) • Anaerobic Biological Treatment • Cleans wastewaters – Many Types • Reduces biomass (0.05 g VSS/ g COD) • Can produce net energy • Considerheating, transport, 4 ft3 CH4 / lb VS as manure
Potential Uses of Process Models: • Reactor Assessment/Optimization • Design • Process Modification
Do Current Process Models Make Predictions of Sufficient Accuracy? Current Industrial Use of Models is very limited Pilot testing still dominant = higher costs = more time Modify Reactor Conditions: pH, T, Feed Type, Feed interval, Mixing Intensity, Nutrients
Anaerobic Process: Modified figure, Gujer and Zhender, 1979
Methane Production Rates-Flowcell Acetate Consumption Rates-GC Three Critical Measurements: Aceticlastic Methanogen Ribosomal DNA Copy # - qPCR
6 Batch Reactors Highly Degraded Manure-Media (MSL) Fed Acetic Acid Acrylic, Rod Mixed Glass, Shaker-Mixed
How are Organisms Identified and Quantified in mixed culture? • Each taxonomic group has ribosomal DNA (rDNA) that is unique to its group • This information is available in public databases. ex: NCBI • rDNA is extracted from samples • quantitative Polymerase Chain Reaction assays quantify the DNA • Technique requires prior knowledge of organism’s genome • Probes and primers complement and bind to target DNA
Methods – Organism Quantification • Collect Sample • Extract and Purify DNA • Quantify the DNA of important anaerobes
Releasing DNA • The key to good analysis is the total release of DNA from the cell. • Use glass beads to beat cells in order to break the cell wall and membrane. DNA Needs to be released by beating with glass beads Olson, UCI, CEE 263, 2008
Flowcell – Basic Principles First Cell Measures Total Gas, Second Cell Measures Methane Glass scrubber with 2 M NaOH to remove CO2. , Bromocresol Green Indicator, color transition, clear to green at pH 12
Two Resistors in Series R1: 12k Ω , R2:Cd_S(1-50)k Ω Single Flowcell Diagram R1 R2 - + FLOW-CELL Volts Gas in Gas Out 15 mC LED & 200 Ω R - 5 V +
Plumping and Circuit Diagram, 6 ReactorsPhysical connections to Match Software Organization PC USB Device R1 R2 R3 R4 R5 R6 1 2 3 4 5 6 7 8