Anaerobic acidogenesis of a complex wastewater: I. The influence of operational parameters on reactor performance

The influence of operational, parameters, such as hydraulic retention time, organic loading rate, influent substrate concentration, pH, and temperature, on the performance of the first phase of anaerobic digestion has been investigated. A complex substrate based on beef extract was used, and six series of experimental runs were conducted, each one showing the effect of one operational variable. The predominant fermentation products were always acetic and propionic acid, independent of the values of the operational parameters. For initial COD concentrations and hydraulic retention times above the critical values identified as 3 g/L and 6 h, respectively, the degree of acidification achieved was between 30 and 60%. The degree of acidification was found to increase with the hydraulic retention time and decrease with the influent substrate concentration and organic loading rate, while the opposite held true for the rate of product formation. Furthermore, it has been demonstrated that acidification is primarily determined by the hydraulic retention time and the rate of product formation by the influent substrate concentration. The concentration of the acetic acid produced was found to depend on the operational parameters. However, the concentration of propionic acid produced depended only on the substrate availability with a consistent proportion of 8% initial COD converted to it. The optimum pH and temperature were 7 and 40°C, respectively. The percentage of acetic acid as a proportion of the total volatile fatty acids produced was found to increase with increasing pH and temperature, while the percentage of propionic acid seemed to decrease accordingly. Finally the effect of the temperature on the rate of acidification followed an Arrhenius type equation with an activation energy equal to 4739 cal/mol.

[1]  K. Wuhrmann,et al.  Kinetic parameters and relative turnovers of some important catabolic reactions in digesting sludge , 1978, Applied and environmental microbiology.

[2]  M. Suidan,et al.  Performance of expanded-bed methanogenic reactor , 1985 .

[3]  R. J. Zoetemeyer,et al.  Influence of temperature on the anaerobic acidification of glucose in a mixed culture forming part of a two-stage digestion process , 1982 .

[4]  Anton M. Breure,et al.  INFLUENCE OF PHASE SEPARATION ON THE ANAEROBIC DIGESTION OF GLUCOSE-~-II , 1982 .

[5]  R. J. Zoetemeyer,et al.  Main characteristics and stoichiometric aspects of acidogenesis of soluble carbohydrate containing wastewaters , 1984 .

[6]  Chiu-Yue Lin,et al.  Methanogenic digestion using mixed substrate of acetic, propionic and butyric acids , 1986 .

[7]  P M Sutton,et al.  Single Phase and Two Phase Anaerobic Stabilization in Fluidized Bed Reactors , 1983 .

[8]  J N Lester,et al.  An evaluation of single- and separated-phase anaerobic industrial wastewater treatment in fluidized bed reactors. , 1984, Biotechnology and bioengineering.

[9]  R. J. Zoetemeyer,et al.  Anaerobic digestion of glucose with separated acid production and methane formation , 1979 .

[10]  R. J. Zoetemeyer,et al.  pH influence on acidogenic dissimilation of glucose in an anaerobic digestor , 1982 .

[11]  M. Dohányos,et al.  Production and Utilization of Volatile Fatty Acids in Various Types of Anaerobic Reactors , 1985 .

[12]  Anton M. Breure,et al.  Influence of phase separation on the anaerobic digestion of glucose—I maximum COD-turnover rate during continuous operation , 1980 .

[13]  N. Draper,et al.  Applied Regression Analysis , 1966 .

[14]  G. Goma,et al.  Characterization of anaerobic microbial culture with high acidogenic activity , 1981 .

[15]  G. Lettinga,et al.  Separation of the propionate degradation to improve the efficiency of thermophilic anaerobic treatment of acidified wastewaters. , 1986 .