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Innovative biological processes for the production of chemicals from organic waste

   School of Engineering

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  Dr D Dionisi, Dr A Majumder  Applications accepted all year round  Self-Funded PhD Students Only

About the Project

The aim of this project is to develop innovative, sustainable and environmentally friendly biological processes for the production of important chemicals such as acetic and butyric acids, ethanol and hydrogen. Currently the production processes for chemicals such as organic acids, e.g. acetic and butyric acid, and hydrogen mainly use oil and gas as starting materials. However, the current processes based on fossil fuels have the disdavantages of consuiming non-renewable resources and of using high-temperature high-pressure processes which cause environmental and safety concerns. As far as ethanol production is concerned, most commercial processes for ethanol production use starch-rich substrates such as corn or sugarcane, which are first chemically hydrolised and then converted to ethanol using pure cultures of selected microorganisms. However, the use of corn and sugarcane is a serious limitation of current processes, since these substrates could otherwise be utilised for food.

Potentially, organic acids, hydrogen and ethanol could be produced using sustainable and renewable starting materials such as organic and agricultural wastes, forestry residues, food waste, etc. These substrated could be fermented anaerobically to yield a mixture of organic acids, ethanol and hydrogen. However, the anaerobic fermentation of these substrates is often limited by their lignocellulosic nature. Lignocellulose is a potential source of fermentable sugars, but its use is very limited due to the lack of suitable and cost effective pretreatment and hydrolisis methods.

The aim of this project is to develop new biological processes for the hydrolysis of lignocellulosic materials and the fermentation of the hydrolysis products into the desired chemicals. The aim is to use naturally-occurring mixed cultures of microorganisms, which are naturally able to produce hydrolytic enzymes, both for the hydrolysis and fermentation processes, which could potentially be coupled in one single stage. This project also aims to investigate the effect of the operating conditions of the bioreactor, e.g. residence time, pH, temperature, acclimation time of the microorganisms, on the conversion of the starting material and on the product yield and composition.
The project will involve running lab scale bioreactors using both model substrates (e.g. glucose, starch, cellulose, model hemicellulose and lignin) and real organic waste (e.g. wood chips, switchgrass, wheat, food waste). The reactors will be run under different conditions, e.g. pH, temperature, residence time, and the conversion of the starting material and the product yield and composition will be measured analytically. Focus will also be given to kinetic modelling of the biological processes occurring. The project will be carried out in the School of Engineering at University of Aberdeen.

The successful candidate should have, or expect to have, an Honours Degree at 2.1 or above (or equivalent) in Chemical Engineering.

Essential background: Chemical Engineering, Chemistry, Biotechnology.

Knowledge or interest in the following:
Chemical reaction kinetics
Biological reactions
Operation of lab scale bioreactors

Funding Notes

This project is for self-funded students only. There is no funding attached to this project. The successful applicant will be expected to pay Tuition Fees and living expenses, from their own resources, for the duration of study.


Dionisi, D. & Silva, IMO. (2016). 'Production of ethanol, organic acids and hydrogen: an opportunity for mixed culture biotechnology?'. Reviews in Environmental Science and Biotechnology, vol 15, no. 2, pp. 213-242. DOI: 10.1007/S11157-016-9393-Y
Silva, IMO. & Dionisi, D. (2016). 'Anaerobic digestion of wheat grass under mesophilic and thermophilic conditions and different inoculum sources'. Chemical Engineering Transactions, vol 50, pp. 19-24. DOI:
Dionisi, D. & Bolaji, IO. (2016). 'Biorefinery with Open Mixed Cultures for Biofuels and Chemicals Production from Organic Waste: Biodegradation of Unpretreated Cellulose'. Chemical Engineering Transactions, vol 49, pp. 157-162. DOI: 10.3303/CET1649027
Dionisi, D., Anderson, JA., Aulenta, F., McCue, A. & Paton, G. (2015). 'The potential of microbial processes for lignocellulosic biomass conversion to ethanol: a review'. Journal of Chemical Technology & Biotechnology, vol 90, no. 3, pp. 366-383. DOI: 10.1002/JCTB.4544


This project is advertised in relation to the research areas of the discipline of Chemical Engineering.

Formal applications can be completed online: You should apply for Degree of Doctor of Philosophy in Engineering, to ensure that your application is passed to the correct College for processing.

NOTE CLEARLY THE NAME OF THE SUPERVISOR AND EXACT PROJECT TITLE YOU WISH TO BE CONSIDERED FOR ON THE APPLICATION FORM. Applicants are limited to applying for a maximum of 2 projects. Any further applications received will be automatically withdrawn.

Informal inquiries can be made to Dr D Dionisi ( with a copy of your curriculum vitae and cover letter. All general enquiries should be directed to the Graduate School Admissions Unit (
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