CHBE 217

Research Summary

Bioprocess Engineering, Anaerobic Fermentation, Bioremediation, Reactor Modeling, Biochemical Reaction Modeling, Reaction Kinetics


University of Toronto, 1992, Ph.D.
University of Cape Town, 1986, M.Sc.
University of Cape Town, 1980, B.Sc.

Research interests + projects

Design and control of complex, multi-phase reactors involves understanding of the reaction kinetics, thermodynamics and transport phenomena of the fundamental processes taking place in the system. The behaviour of a combination of well characterized, single step processes that are inter-related cannot be intuitively extrapolated, necessarily, from knowledge of the individual steps. Therefore, mathematical models of such complex processes are very useful for elucidating their expected behaviour under a wide variety of conditions. These models can yield unanticipated, non-intuitive results that, often, are realized as improvements to the process. However, the understanding of complex reaction processes, intuitively or mathematically derived, is still founded on accurate and thorough experimental data.

Natural processes, in particular, lend themselves to intractability. Dr. Baldwin’s research has focused on the seemingly impossible task of understanding and possibly controlling a diverse number of processes from blood coagulation to mineral dissolution and precipitation. Despite being vastly different systems, structural similarities in reaction networks result in repeatable patterns of behaviour.

In blood coagulation, modelling the effect of cell surface coverage of enzyme-cofactor complexes in thrombin formation have revealed interesting results. Surprising results include the suggestion that some procoagulants act as progoagulants only at low concentrations and their role shifts to inhibition as they accumulate.

In the mineral processing field, two areas are being studied: oxidative leaching of minerals under high temperatures and pressures, and bacterially mediated precipitation of heavy and toxic metals from aqueous streams. In the first case, steady state and dynamic models are being used to study pressure oxidation autoclaves. These are used to extract metal values, such as copper, zinc and gold, from ores and concentrates. In the second area, in a reverse process, metals are being removed from contaminated aqueous streams using anaerobic bacteria. These provide the reducing conditions and also act as nucleation sites for mineral precipitation. Acid rock drainage and Cr-As- areas. Cu contaminated water from wood-treatment sites are being treated using sulphate reducing bacteria to facilitate metal precipitation. Novel reactor designs are being investigated to enhance kinetics of precipitation and separation of the metals from each other.

Other areas being embarked upon include cultivation of marine organisms such as sponges so as to obtain secondary metabolites useful as pharmaceuticals, and food processing.

Scholarly and professional activities + affiliations

American Chemical Society
American Society for Microbiology
Society for Industrial Microbiology
British Columbia Water Association