Researchers develop greener approach for producing cheaper biodiesel from microbes, sludge

In Canada, researchers at the Institut National de la Recherche Scientifique developed a new approach to biodiesel production that uses microbes, sewage sludge, and glycerol, a biofuel byproduct and were able to lower the production cost down to $0.72/L with their new innovative new process.

Processing sludge reduces GHG. “It keeps sludge out of landfills, where it releases methane. When it’s used to produce biodiesel, most of the carbon is transformed into lipids by the microorganisms,” said Professor Tyagi. The process also makes it possible to reuse the glycerol without having to purify it.

In the first stage of fermentation, the microorganisms eat the glycerol and the sewage sludge. They accumulate oil in their bodies in the form of lipids. The INRS researchers use a bioflocculant—an organic polymer secreted by organisms—to separate the cells from the mixture and extract the lipids. That eliminates the need for centrifuges or chemical products.

In order to recover the lipids extracted from the cells, Professors Tyagi and Drogui replaced those toxic chemical products with gas. The gas added for separation is also part of the final product.

The process produces biodiesel and glycerol, which could in turn be used to produce more fuel. But plants don’t necessarily use the same production processes, so the glycerol, and its efficiency, may vary. Professors Tyagi and Drogui are looking to figure out how to combine these different byproducts to make the process even more cost effective.