Biodiesel and potential use of algae for wastewater cleanup

In “Biodiesel: Cultivating Alternative Fuels,” Charles Schmidt provides a fairly comprehensive overview of the basic effects of producing biodiesel.  He first examines the recent history of biofuels in America, starting with the early 1990’s when the realization that biofuels could be an economically advantageous solution to petroleum based fuels occurred.  From there, Schmidt moves on to a description of basic diesel engine operations, and finally to the advantages and disadvantages of different sources of biofuels.  Most of these advantages and disadvantages have been discussed in class recently, such as the area required for corn based ethanol and the displacement of cropland for fuel-land.  However, two arguments were new or discussed differently.

One of these new arguments against biodiesel was that it tends to gel up easier and at higher temperatures than petroleum based diesel.  Summer grade petroleum diesel does this too, albeit to a lesser degree, in the winter.  Most fuel companies in colder climates switch to a different grade of diesel fuel in the winter that is less prone to this problem.  The problem can be reduced in petroleum based summer diesel fuels by adding a small amount of gasoline to the tank.  However, Schmidt did not mention this as a possible solution with biodiesel.  Therefore, it would seem this still remains a problem for biodiesel.

The second topic, discussed only briefly in class, is that using nutrients from wastewater plants to fertilize algae sources of biodiesel.  Schmidt claims that the most promising source of biodiesel comes from algae (because it can produce up to 8,000 gallons per acre compared to soybeans which can produce around 50 gal. per acre) that is fertilized with wastewater.  This does seem an highly viable route.  However, it is not the best.  In both a 2009 abstract and his 2007 master’s thesis, Ian Woertz studies the use of algae to simultaneously produce lipids for use as biodiesel and clean up wastewater.  Currently, Woertz is continuing bench tests of this treatment form.  These tests seem highly promising.  Common levels of orthophosphate removal are on the scale of 88-92% and removal of nitrogen is around 95-96% in wastewater treatment plants.  This is typically done with single celled organisms.  The results from Woertz’s bench tests indicate that phosphate removal with certain types of algae (that could then be used for fuel) is around 96% and N removal is “>99%” (Woertz, 2009).  The double use of algae seems an even more promising option.

Schmidt, Charles W. 2007. “Biodiesel: cultivating alternative fuels.” Environmental Health Perspectives. 115:2, A86-A91. URL.: < >.

Woertz, I. 2007.  Lipid production of algae grown on dairy wastewater as a possible feedstock for biodiesel. (Master’s Thesis, California Polytechnic University: San Luis Obispo). 1-87.  URL.: < >.

Woertz, I, A Feffer, T Lundquist, and Y Nelson. 2009. “Algae grown on dairy and municipal wastewater for simultaneous nutrient removal and lipid production.” Journal of Environmental Engineering-ASCE. 135:11, p. 1115-1122. URL.: < >.


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