The application of high pressure and steam is a proven method for the mobilisation of valuable components from biomass. Wageningen Food & Biobased Research is contributing to the project "Production of butanol and hydrogen by fermentation techniques using steam treated municipal solid waste (MSWBH)" with its expertise on fermentation and the use of anaerobic bacteria for the production of biobased chemicals.
Wageningen/The Netherlands — MSWBH uses municipal waste in the United Kingdom to produce feedstock for fermentation into butanol and hydrogen, which are important fuels and chemicals. The project contributes to the EU's commitment to ensure that 10 % of all transport fuels are biobased by 2020.
“The United Kingdom has a post-separation system of treating municipal waste, which means that the organic waste is not collected separately,” explains Pieternel Claassen, a senior scientist at Wageningen Food & Biobased Research involved in the project. If organic residues are to be recovered, MSW needs to be fractionated first to remove plastics, metals and other inorganic components. Treating MSW with high pressure and steam produces a carbohydrate-rich stream. This stream is converted at Wageningen Food & Biobased Research into butanol and hydrogen by anaerobic bacteria during a fermentation process.
From Hydrolysis via Fermentation to Butanol and Hydrogen
The Wageningen part of the research focuses on the effects of the pre-treatment on the fermentation. Municipal waste is treated in an autoclave-type equipment at the Biorenewables Development Centre (BDC) in York. This is done to make the waste easier to degrade and for sanitation purposes. The carbohydrates in the pre-treated material are hydrolysed by enzymes, and the resulting sugar stream is sent to our lab. The microorganisms producing butanol and hydrogen are anaerobic bacteria that can use many different sugars.
Claassen explains: “In MSWBH, we study and optimise the use of the sugars and also determine the effect of other components on the growth of the bacteria." The organic fraction coming from MSW contains many different components from all kinds of sources, including plants, food waste and paper. This can affect the fermentation performance. At the end of the project, the developed technology will be scaled up in a pilot facility at the BDC in York. The complete fermentation including processing to pure butanol and hydrogen will be realised in Wageningen.
Advantages of Organic Waste for Butanol and Hydrogen
According to Claassen, the use of organic waste from MSW as a raw material for fuels or chemicals like butanol and hydrogen offers significant benefits over current processes. The most common biofuel today, bioethanol, is mainly produced from food crops such as corn. Apart from the food versus fuel discussion, the main disadvantage of this is financial: the raw materials and their treatment generally make up around 70 % of the costs. The use of MSW as a raw material for biofuels and chemicals can limit feedstock costs and in MSWBH new and cheap pre-treatment procedures are developed, allowing for an economically viable production process, the scientists claim.
The MSWBH project started in April 2016 and has a duration of three years. The data obtained during the research and the pilot phases will provide a basis on which to evaluate the technical and economic feasibility of the new process.