A Multistage Fermentation System for
Fundamental Anaerobic Digestion Research
FRANK D. SCHAUMBURG, Senior Research Engineer
British Columbia Research Council
Vancouver, British Columbia
EDWIN J. KIRSCH, Associate Professor
Civil Engineering Department
Purdue University
Lafayette, Indiana
INTRODUCTION
Fundamental research on the anaerobic digestion process has been intensively
conducted during the past several years. The voluminous literature is a testimony
to the magnitude of research effort directed towards this biological waste treatment process. Of major concern has been an exhaustive description of the physical, chemical and engineering aspects of the process environment and how these
influence sludge digestion. Pohland (1) in his thorough survey on the anaerobic
treatment of sludge cites numerous research reports which emphasized such parameters as temperature, pH, volatile acid concentration, alkalinity, "salt toxicity, " loading weight, etc. Heukelekian, et al (2) has pointed out that much of
the information which has been amassed from years of research is somewhat superficial. He emphasizes the need for pioneering efforts to investigate rudiments of
biological importance, such as the succession and interaction of micro-organisms.
Unfortunately, efforts to study the community of anaerobes has been thwarted by
the lack of suitable laboratory apparatus and technique. Buswell etal(3), referring to the biphasic digestion process, pointed out this deficiency when he
wrote, "The bacterial flora, although composed of a variety of organisms, has
not yielded to any simple procedure for analysis. If the acid formers and methane
formers could be identified and counted, the control of digestion would be rather
simple.   Unfortunately, this is not yet the case."
Motivated by the obvious need for a clearer understanding of the microbial
community important in the anaerobic digestion process, this study was undertaken
to develop a laboratory system in which various species of microbes could be observed as individual pure cultures while sharing a common environment.
A literature search indicated that only limited effort has been extended to
study mixed microbial communities in a liquid environment. In 1955 Nurmikko
(4,5) reported the development of a simple dialysis cell, compartmented by semipermeable membranes, to observe associative and symbiotic interrelationships
among selected species of aerobically-grown microorganisms. The technique employed by Nurmikko, although not readily adaptable to anaerobic methodology,
offered a promising avenue for further exploitation. Gallup and Gerhardt(6) in
1963 reported the development of a dialysis-fermenter system to supply nutrients
to and remove metabolic waste products from aerobically-grown bacterial cultures. Their expressed objective, however, centered on the concentration of
growing bacterial cultures.
Initial efforts in this study were aimed at modifying the dialysis-fermenter
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