Microbiological processes for waste conversion tobioenergy products: Approaches and directions

摘要

Waste disposal is one of the most pressing concerns facing modern society. It is becoming increasingly apparentthat the majority of organic waste from various residential, agricultural, and industrial sources can be converted by microorganismsinto biofuels. These fuels provide valuable renewable energy sources that could significantly lower greenhouse gasemissions such as the passive release of methane from landfill sites. There are four types of biofuels that are produced bymicrobial action: (i) algal lipids, (ii) alcohols, (iii) methane, and (iv) hydrogen. In contrast to the others, methane productionis the product of relatively robust microbial communities. Furthermore, methane can be produced from the residues of otherbiofuel production systems. The other biofuels are generally produced in single-organism systems, but there is increasing interestin employing syntrophic interaction between microorganisms for their manufacture. This is particularly true for thecellulosic production of ethanol and hydrogen, where cellulose must first be degraded into glucose. Algal lipids made withwaste CO2 from the burning of fuel, and wastewater and wastewater sludge as nutrients, is the only biofuel efficiently producedby algae; however, algae grown on waste material also shows promise as feedstock for the production of other biofuels.The processing of biomass through two or more of these production systems would optimize waste conversion intobiofuels.