Characterization and modeling the dynamic response of butyrate, acetate, and hydrogen utilization in anaerobic fluidized-bed reactors

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6017698

Labib, F

Two continuous flow anaerobic fluidized-bed reactors were utilized to study the characteristics of an acetate-fed and a butyrate-fed microbial culture at steady state and under transient loadings. A mathematical model of the butyrate-fed reactor was developed and calibrated using the experimental results obtained from this reactor. The model could simulate the reactor response to various transient loadings of butyrate, acetate, and hydrogen and was used to predict its response to loadings with potential to cause process failure. At steady state, the specific COD removal rate in the butyrate-fed reactor was about 7 to 9 gCOD/gVS-d and COD removal was greater than 95%. About 95% of the COD removed was converted to methane. The estimated solids retention time (SRT) in the butyrate-fed reactor was under 10 days. At steady state, methanogenesis from acetate was almost saturated (about 80% of the maximum capacity), the butyrate oxidizing capacity was about three times its utilization rate at steady state, and the methanogenic capacity of the H{sub 2}-utilizers was more than ten times its rate at steady state. Formate was used by this culture, and during its metabolism P{sub CO} increased by over 150 fold, and P{sub H2} increased by 10 fold. The methanogenic culture in the acetate-fed reactor was unable to utilize H{sub 2} or formate, and increases in P{sub H2} inhibited methanogenesis from acetate. Application of the butyrate reactor model to various reactor over-loads showed that the pH drop associated with the VFA accumulation to be a major factor in process failure. The model showed higher SRTs could significantly reduce the VFA accumulation and enhance stability of the process. Acetate overloadings, but not H{sub 2} overloadings, predicted potential washout of acetogens and process failure.

• Research Organization: Washington Univ., Seattle, WA (USA)
• OSTI ID: 6017698
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090900* -- Biomass Fuels-- Processing-- (1990-)
ACETATES
ALKANES
ANAEROBIC DIGESTION
BACTERIA
BIOCONVERSION
BIOREACTORS
BIOSYNTHESIS
BUTYRIC ACID
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CHEMICAL OXYGEN DEMAND
CONTINUOUS CULTURE
DATA ACQUISITION
DIGESTION
ELEMENTS
FAILURES
FLUIDIZED BEDS
FORMATES
FUNCTIONS
HYDROCARBONS
HYDROGEN
INHIBITION
LOADING RATE
MANAGEMENT
MATHEMATICAL MODELS
METHANE
METHANOGENIC BACTERIA
MICROORGANISMS
MONOCARBOXYLIC ACIDS
NONMETALS
ON-LINE MEASUREMENT SYSTEMS
ON-LINE SYSTEMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PH VALUE
PROCESSING
PRODUCTIVITY
RESPONSE FUNCTIONS
STEADY-STATE CONDITIONS
SYNTHESIS
TIME DEPENDENCE
TRANSIENTS
WASTE MANAGEMENT
WASTE PROCESSING