I am by training a Chemical Engineer now retired after a career in academia and the Idaho National Laboratory specialising in large-scale bioprocess such as wastewater treatment, biomining and environmental remediation. While remaining intellectually active in retirement I stumbled somewhat serendipitously upon a consistent single solution to the two great philosophical difficulties of modern physics, the nature of time and the source of the quantum. This work is summarised on the Research Blog page of this site.
RESEARCH HISTORY AND PHILOSOPHY
Engineers are often thought of as people who design build and operate useful devices and processes, but this is inexact. Given a requirement, let's say "Extract the metal from this ore", there are many possible processes, some physical, some chemical, some even microbiological. It does not take a lot of education to choose one and make it work (which is why there was mining for centuries before there were Schools of Mines) but this is not engineering. The task of the engineer is to consider all the possibilities and choose the one that works best, which usually means at the lowest total cost. It is essentially an economic optimization problem, the intellectual challenge being that in practice there is never enough time, money or information to find the exact solution. We must therefore proceed to a best possible solution by a judicious mix of the available tools, experience, experiment and mathematical modelling. The role of the academic engineer, besides educating the next generation, is thus two-fold. They must keep up a steady supply of new ideas for how to solve society's problems, and refine the tools available for identifying the optimum solutions to these problems. These have been the themes of my work, most of which has involved large-scale microbial processes.
Bacteria and adsortion on activated carbon were once seen as competing methods for treating sewage and industrial wastewaters. However, people operating adsorption columns found that bacteria would grow naturally on the carbon particles, often plugging them up, while those operating biological processes found that the addition of powdered activated carbon could improve their performance by removing contaminants that were resistant, or even harmful, to microbial metabolism. My Ph.D. research involved sorting out the interactions between the two types of process in search of an optimum combination (see refs (1) and (2) on Publications page). The plugging problem could be avoided by replacing the packed bed with a fluidized bed of particles on which the bacteria could grow as a biofilm. This led to a general interest in fluidized-bed bioreactors (3), including those for the production of chemicals by fermentation (4).
Engineers must deal with the real world which is a notoriously complex place, and there are many situations in which it is possible to write down the equations describing a process only to find they are too difficult to solve. The greatest advance in tools for engineers in my lifetime was thus the appearance of the computer and, like many others, I could not resist the temptation to work out a problem that was previously intractable. I chose the flow around a gas bubble rising through a liquid containing surface-active solutes (5). The application to bioprocesses involves the rate of transfer of oxygen from air bubbles.
Unlike physical and chemical processes the mathematical modelling of biological processes is not well developed, mainly because living systems are simply too complicated to describe exactly. I was the first to show that the yields of bioprocesses could be well approximated from element and energy balances over the particular microbial metabolism, as long as the energy was expressed properly in moles of ATP (6).
While at the University of Buffalo I started some of the earliest resarch on the microbial removal of pyritic sulfur from coal (7), and moving to the Idaho National Engineering Laboratory allowed this work to be extended to a larger scale (8). The theme of optimization by combining different types of process reappeared here, for the larger inclusions of pyrite are easily removed using physical processes, while the bacteria work fastest on the smaller inclusions that this conventional technology does not touch. Working in the DOE lab system in the 1990's inevitably got me involved in the clean-up of past environmental disasters. I served on the advisory committee for the bioremediation of a trichloro-ethylene spill at the Savanna River site. I also explored the possibility of a bioprocess to treat the highly radioactive supernatant from the waste tanks at Hanford. It involved the conversion of the high levels of nitrate directly into carbonate to make glass, a reaction that is almost impossible chemically but is a natural consequence of the metabolism of denitrifying bacteria.
One of the most useful tools for engineering scale-up is the strange subject of Dimensional Analysis. It is a kind of lowest common denominator of mathematical modelling used, for example, to translate data obtained from model airplanes in wind tunnels to predict the performance of the full-scale plane. It is based on Reynold's Similarity Principle, which states that two physical situations are similar if all of the relevant dimensionless numbers are the same. I had long been interested in the questions of why it works and what exactly "similar" means (10) and retirement allowed me to return to these mysteries. It inevitably led to questions about the exact intellectual status of the so-called "fundamental" dimensions, mass, length and time. To my surprise this proved to be an unexplored path into the foundations of physics, one that led to the results described on the Research Blog page.
