Converting wastewater treatment facilities into biorefineries: biodiesel from wastewater microorganisms

Abstract

In a world with growing energy demands, increasing dependence on fossil fuels has become the norm, but given the finite supply of these fuels, this is no longer a sustainable approach. Biodiesel is one alternative renewable fuel source with great promise. Unlike other forms of renewable energy, biodiesel is directly usable in existing forms of technology, such as the diesel engine, and does not require significant retrofitting. Biodiesel is composed of fatty acid esters, like fatty acid methyl ester (FAME), which are made via the transesterification reaction, wherein fatty acids are esterified with alcohol in the presence of a catalyst. Traditionally biodiesel has been produced from vegetable oils, however, recently many alternative feedstocks, such as used cooking oil, have been gaining significant attention. One interesting alternative feedstock with very limited research is wastewater sludge, a major by product of the wastewater treatment process. Rich in fatty acids that are ripe for transesterification, wastewater sludge offers significant potential as a biodiesel feedstock.