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Novel reverse membrane bioreactor for second generation bioethanol developed

Using wastewater treatment technology for bioethanol production from agricultural waste is now a possibility thanks to a reverse membrane bioreactor, quite unique in its kind. It was developed and described by Amir Mahboubi Soufiani who recently defended his doctoral thesis in Resource Recovery at the University of Borås in Sweden.

Using wastewater treatment technology for bioethanol production from agricultural waste is now a possibility thanks to a reverse membrane bioreactor, quite unique in its kind. It was developed and described by Amir Mahboubi Soufiani who recently defended his doctoral thesis in Resource Recovery at the University of Borås in Sweden (photo courtesy University of Borås).

In his doctoral thesis “Immersed flat-sheet membrane bioreactors for lignocellulosic bioethanol production“, Amir Mahboubi Soufiani describes his PhD project where he focussed on two processes: one to treat wastewater where the product is purified water and the other related to second-generation bioethanol production. The latter is something encouraged by EU directives to increase the proportion of renewable biofuels.

There are many advantages to it; For example, the substrate, i.e. the raw material, comes from a residual product. In my study, it comes from agriculture and cultivation of wheat. It benefits the planet from not using a raw material that could be used for food or animal feed, said Amir Mahboubi Soufiani.

Amir Mahboubi Soufiani used wheat straw, a residual product from harvesting wheat, which with the help of yeast is converted into ethanol.

For every kilo of wheat grain harvested, 1.3–1.4 kilos of wheat straw is left over, which are currently burned or turned into biofuel. In 2019-2020, 2 175 million tonnes of wheat will be harvested worldwide. Imagine how many tonnes of wheat straw that means. But these are raw materials with great potential–not waste, said Amir Mahboubi Soufiani.

Novel reverse membrane bioreactor

Until now, the process of producing second-generation bioethanol has brought with it technical and economic challenges. What Amir Mahboubi Soufiani has done and described in his thesis is to use a process used to treat wastewater in order to produce bioethanol.

By merging two technologies, we have increased productivity and returns while reducing the size, the number of steps, and also the environmental footprint, Amir Mahboubi Soufiani said

In addition, he has developed a completely new technical solution: a new membrane. Membranes act as a colander so that it is possible to keep what is desirable inside the reactor while the rest is filtered out. The new membrane means the process can be tailored so that the product comes out as quickly as possible and in addition is clean and highly concentrated.

With this, Amir Mahboubi Soufiani has addressed several technical challenges faced in the commercial production of lignocellulosic bioethanol and above all has opened up new application horizons for membrane bioreactors other than in wastewater treatment plants (WWTP).

The new membrane bioreactor developed in this work is called a “reverse membrane bioreactor” and the university together with the funder, the Flemish Institute for Technological Research (VITO NV) in Belgium, has now patented.

Without it, the technology could have worked anyway, but it would not have been optimal said Amir Mahboubi Soufiani adding that the technology can be applied in several different areas; the next step is to produce fatty acids instead of bioethanol.

Amir Mahboubi Soufiani says that there is a great interest in the technology both in the ethanol industry but also in relation to the treatment of wastewater. His research continues at the University of Borås.

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