Print this pageEcological Engineering in Anaerobic Digestion and Naturally Occurring Shallow Biogenic Gas Sources
More than three thousand years ago, mankind started using one of the first applications of biotechnology. The intentional transfer of naturally-occurring microbial communities from the gut of ruminants and monogastric animals, such as man himself, initiated the anaerobic digestion technology. Its application to the treatment of man-made and man-generated wastes with the production of energy, i.e. methane, is a valuable technology in today’s energy-hungry world. Ecological engineering merges traditional engineering with microbial ecology to control and maximize the biological biogas output from a variety of organic feedstock or residuals. 200+ anaerobic bacterial species coexist and cooperate in ecological interactions to metabolize complex organic feedstock. These include animal manure human wastes, municipal solid wastes, organic agricultural and manufacturing wastes / wastewater. The product is biogas comprised of 50% to 80% methane plus 20% to 50% carbon dioxide and traces of other gases. Ecological engineering uses common techniques of civic, chemical, and biochemical engineering to understand and control ecological parameters. Parameters include microbial population levels and dynamics; biofilm production and maintenance; physical parameters, such as pH, Eh, alkalinity; and chemical factors, including concentrations and proportions of nutrients such as volatile fatty acids; and inhibitors, such as ammonia and hydrogen sulfide. Ecological engineering has been successfully applied to anaerobic bio-reactors and landfill cells to increase biogas output. Biofilm formation and maintenance is important, and this community structure can be monitored and stimulated in digesters, landfill cells, and shallow coal beds. These biogas sources include shallow coal beds that are cost prohibited to mine due to the coal’s poor heating quality, or the location of deposits underneath environmentally sensitive environments These ecological engineering techniques can be used to maximize and maintain other naturally-occurring shallow biogenic (bio)gas sources. Faced with unique challenges within these systems, a number of techniques have and can be modified from digester technologies and applied to these biogas sources.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009