Fermentation

 

Bioprocesses

fermentation schematic overview
Introduction:

The biobased production of platform chemicals from organic waste streams is a green alternative for their current petroleum based production. One option to produce such chemicals relies on bioconversions, such as fermentation. Fermentation is a metabolic process in which an organism converts substrates into products, e.g. alcohols or organic acids. For example, yeasts ferment carbohydrates into alcohol while lactic acid bacteria convert carbohydrates into lactic acid.

Potential:

Fermentation has the potential for the production of bio-based chemicals out of organic waste streams. To be able to tap the full potential of organic waste streams, the waste streams first need to be hydrolyzed. In a second step, the actual biocatalysis step is applied to produce the target platform chemical. 

Aim:

The main aim of current research projects is to improve productivities of the fermentation processes, for instance by combining the fermentation process with a separation technology to remove inhibitory effects.

 

Difference to BAU technology/approach:

Current treatment approaches for organic waste streams include biological treatment in the presence or absence of oxygen. In the latter case, the organic substrates are converted into methane, which can be valorized for its energy content. Other biological alternatives under investigation are the production of hydrogen from organic waste streams.

The biobased economy is based on the conversion of biomass feedstocks into building blocks, from which a series of chemicals can be produced. Many of the conversions are based on biological processes and fermentation. As the trend is towards the use of waste streams instead of pure sugars, organic waste treatment through fermentation can be combined with waste valorization towards a broad range of products. The production of energy or heat as from methane/biogas is then situated lower in the ecovalue pyramid than production of fuels and bulk chemicals, biopolymers, etc

 

Input stream requirements:

Any organic waste stream from which substantial amounts of sugars can be released through enzymatic pretreatment can be suitable. Butanol can be produced from a broad series of waste streams, because several of the relevant bacteria are capable of growing both on C5 and C6 sugars. For succinate production, this presents a bigger challenge as the micro-organisms are less versatile in substrate spectrum. We propose to work on paper waste streams, from which sugars can be released through proper pretreatment.


Paper waste

Available quantity:

Organic waste streams and paper waste in particular are widely available.

Drivers for treating this stream:

Large amounts of paper waste are available and the option of converting them into biobased chemicals might be quite attractive as the capacity to recycle them has already been reached locally.

Potential environmental risks related to this waste stream:

No major risks, but upgrading and valorization in a closed loop or biorefinery concept is evidently preferable to disposal.

Economic/technical barriers to collect this stream:

Limited, as paper waste is already collected.

Output stream:

Organic: acids, alcohols, usually in mixtures. In this project we mainly aim at butanol or succinate production.


Butanol

Potential uses of this output stream:

The acids or alcohols can be used as such or can be used as intermediates for a next bioconversion or chemical process to provide fine chemicals or biofuels.

Potential environmental risks/benefits related to this output stream:

In general, the environmental impact of biofuels and biobased chemicals is expected to be less than for their petroleum-based alternatives.

Economic barriers/drivers for market introduction of this output stream:

Butanol is a better fuel than ethanol and the first full-scale demonstrations are there. For succinic acid, several joint ventures with major chemical companies have been realized and the first industrial productions have been achieved. The question is how big the demand will be for the biobased succinic acid.

Technical barriers for market introduction of this output stream:

None

Legislative barriers for market introduction of this output stream:

None

Pilot description:

The system consists of a feed tank containing the waste stream, a fermentor inoculated with the required microbial consortium or pure culture depending on the waste stream and/or the desired product and a separation step for (selective) recovery of the target product.


Butanol fementation process integrated with a pervaporation process

Installation:

The core is a fermentor. To increase productivities, the fermentor can be combined with separation technologies that allow the recovery of the target products (e.g. pervaporation for removal of butanol, electrodialysis for removal of organic acid salts, etc.).

Pilot fermentation installation


 

Capacity:

2-10 L fermentor volume

Scale of the equipment:

Large lab scale

Main technological barriers for market introduction:

Current applications mainly use pure sugar media as starting material for fermentation. Processes occur batchwise and under sterilized conditions. Shifting to continuous operation may improve productivities but presents a risk of contamination. The use of waste streams leads to higher levels of impurities and higher requirements in terms of separation and purification.

Main economic barriers/drivers for market introduction:

Substrate and downstream processing are a major cost factor in fermentation processes. Shifting from pure sugar substrates to organic waste streams saves on substrate costs. However, the higher separation and purification needs due to a complex feed and product mixture lead to increased downstream processing costs.

Research steps:

General need for upscaling and demonstration of robustness.
 

Economic steps:

Technical economical evaluation of the technology is needed compared to base case.
As the technology is not yet applied at a large scale, certain components may still be quite expensive.

Legislative steps:

There is a general interest in waste valorization, biorefinery concepts and production of biobased chemicals already, but legislative incentives always help to introduce new technologies.

Other:

  Expected time to market: 5 years

 ‌

Contact details:

Organisation: VITO

Department: Separation and Conversion Technology

Leading researcher: Heleen De Wever

Phone number: +32 14 33 69 32

E-mail: heleen.dewever@vito.be

 

Documentation:

Presentation: Improving productivities in fermentation processes, VITO, Heleen De Wever, RENEW Technology Foresight Conference 24/04/2013