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Development of competitive, next generation biofuels from municipal solid waste

Periodic Reporting for period 2 - BioRen (Development of competitive, next generation biofuels from municipal solid waste)

Reporting period: 2020-05-01 to 2021-04-30

Worldwide the majority of municipal solid waste is either landfilled or incinerated. The EU is taking a leading role in towards valorisation and/or recycling components out of the waste streams. The EU has a policy to diminish this incineration, whereas there are many valuable components present which can be transformed into energy resources (electricity, biofuels, hydrogen, syngas, methane) and preferably recycled into the original pure products and transfored into new materials and products.

This is important for the society and especially the environmental impact lowering the CO2 generation and producing sustainable energy, products and materials. It is a stimuli for the society to lower streams and to perform a selection of various components in waste at the source of production (glass, plastics, biomass, inerts).

The objective of Bioren is the development of a sustainable and techno-economicical production of biofuels for transportation purposed from the Organic fraction of municipal solid waste (OFMSW). This project is targeted on the conversion of mainly cellulosic waste stream (paper, cardboard) into ethanol and isobutanol via enzymatic hydrolysis followed by fermentation. Another high value biofuel is glycerol tertair butylether which is a highly promising fuel additive for both diesel and gasoline enhancing engine performance and reduction of harmful exhaust components. GTBE is produced via catalytic dehydration of isobutanol into isobutene which is reacting with glycerol (derived from the biodiesel production) to form GTBE. The fermantation residue and/or the excess of OFMSW is converted into biocoal via a hydrothermal carbonisation (HTC). Bioren is capable of converting the majority of OFMSW into valuable products in the framework of the Circular Economy.
The first step in the Bioren process is the design of a separation line using a combination of techniques to isolate the organic fraction. On average MSW contains 30-40% of biomass. the organic fraction is separated from the other components regarding the different physical and chemical properties. The sorting line is designed by Drysep in collaboration with the engineering team of Renasci. The sorting line plays a dominant role in the effectiveness of the next steps in the Bioren project.

Labo Vossen in collaboration with VIB and BBEPP developed a rapid pre-treatment involving an acid treatment leading to an optimised accessibility for enzymatic hydrolysis of the cellulose and hemicellulose into a C6/C5 sugar solution. In order to produce cellulose streams of a high quality a system is developped for a preliminary deinking and deashing process which would give use to higher ethanol production.

VIB has the task of development of strains followed by the evaluation of these strains in enzymatic hydrolysis and fermentation. VIB developed 2G ethanol yeast strains capable of efficiently fermenting both pentose and hexose sugars. It was confirmed that the xylose fermentation performance of the engineered strains was improved. VIB has performed various enzymatic hydrolysis in various conditions were reported in order to compare on lab-scale the efficiency on the enzymatic hydrolysis and subsequent fermentation. This in order to reach a productivity of at least 11.5 g/l/h ethanol productivity , a high yield (> 90% of total sugar) and final ethanol titer (>6% v/v). Using the cellulase Cellic CTEC3 at a concentration of 150 ul/g DS iand a saccharification efficiency of 75-90% has been obtained dependent on the nature of the samples and the pre-treatment conditions.
Also the reaction conditions of the saccharification gave a considerable increase in saccharification efficiency and also to reduce the enzymatic dosage to 3,75 FPU/g DS.

Several saccharification and fermentation of clean cardboard and paper/cardboard have been performed on lab-scale and pilot plant scale. A demonstration SSF process (2m3 scale) on paper and cardboard was set up. The saccharification was executed according to a fed-batch strategy. The paper/cardboard was pulped (15%) and treated with 5% Cellic CTEC 3 enzymes and gradually paper/cardboard was added up, after 60 hours an ethanol concentration of 8.5% v/v was obtained.

After the fermentation the remaining solids of the broth were separated off using a decanter centrifuge were sent to Ingelia for the hydrothermal carbonisation for the production of Biocoal. The carbonisation is performed in an inverted flow reactor at 200-225°C at 18 bar. This followed by filtration of the carbon deposits. A bust test was done on a 5kg sample supplied by BBEU. Experiments showed that all treatments are increasing the fixed carbon by at least 50% of its original value in biomass giving a yield of 65-70%.

Procede has produced samples of GTBE for engine testing at Lund university. GTBE is an efficient fuel additive for enhancing engine performance and lowering emissions for gasoline and diesel. GTBE is produced from glycerol by reaction with isobutene. GTBE is a mixture of three components mono GTBE, di-GTBE and tri-GTBE. All components are being tested on performance. These samples have been produced by commercial isobutene. Experiments have started to evaluate isobutene production from isobutanol via catalytic dehydration. In the future, this procedure will be applied on the isobutanol produced by fermentation.

Preliminary results on engine testing on the performance of GTBE and isobutanol as oxygenated additives for diesel. These test revealed that all oxygenated blends (3-5%) resulted in an overall decreased soot emissions, but some blends showed an increase in NOx. The emissions of CO and total hydrocarbon content THC were low.

a literature analysis dealing with LCA and LCC in the field of the environmental impact of biofuels production, distribution and combustion was performed by MEERI. This overview involves both biofuels of 1st and 2nd generation based on literature data and information from Bioren partners.
A unique separation and sorting line is designed by Drysep and Decide and is fully operating at Renasci Ostend. The combination of acid pretreatment of the organic fraction followed by enzymatic hydrolysis at rather low concentrations of hydrolases and fermentation of the procured sugar solutions provided an ethanol solution of 8,5% vol %. This is one of the highest yield in comparison with the results of the literature on cellulosic ethanol and the first using the organic fraction of municipal waste. The economics of this process can be enhanced on the condition that the price of the enzymes are decreased. That can be expected if higher amounts can be used in the product of cellulosic ethanol. In the second part of the project the emphasis will be concentrated on the isobutanol production and the transformation into isobutene. The production of GTBE has been developed but major engine testing is lacking and will be one of the highlights. It is very important to stress that other products in the waste streams are isolated and transformed into biofuels via pyrolysis of plastics while other components are gasified via a thermo-chemical pyrolysis and used as energy sources. In this way the Bioren project is energy neutral.
The socio economic impact is high due to the simultaneous production of energy, biofuel, products and materials. The Bioren and Renasci project creates new opportunities in the society for the integral valorization of waste streams.