The world population is steadily growing, and so is the amount of waste produced by human activity. For example, an estimated 236 million tons of municipal solid waste are produced annually in the U.S., 50% of which is biomass. At the same time, energy sources are rapidly depleting. Converting organic waste to renewable biofuel by anaerobic digestion hence represents one appealing option to mitigate this problem.
Biogas is a natural by-product of the decomposition of organic matter in an oxygen-free environment and comprises primarily methane and carbon dioxide. This naturally occurring process has been known for more than a century. More recently, it has been gaining importance as more efficient anaerobic digestion technologies have been developed to treat and recover energy (in the form of biogas) from municipal, agricultural and industrial organic wastes.
The anaerobic digestion process happens slowly in nature, and there is a great need to speed it up in a human-controlled environment in order to harness it for developing sustainable biofuel. Researchers at UC Davis have recently developed a high-rate anaerobic digestion system, the Anaerobic Phased Solids Digester (APS-Digester), that can quickly convert solid food and green waste into hydrogen and methane gas on a large scale. The microbial community involved is very complex, and so far little is known about the specific microorganisms involved, their relative abundance, biology, metabolic capability, and responses to environmental conditions and specific substrates. This is because members of this consortium are often engaged in metabolic symbiosis, which makes them hard to culture in isolation and hampers almost every aspect of conventional studies of these organisms. Therefore there is an ideal opportunity to use culture-independent, high-throughput DNA sequencing technology to study the microbial diversity and explore the largely untapped metabolic reservoir of this microbial community, correlating engineering design with microbiology to improve the process.
Principal Investigator: Martin Wu (Univ. of California, Davis)