Getting Supercritical


Prof. William Jacoby and research assistant Nick Wilkinson stand next to the biomass supercritical water gasification reactor. Image:

It’s easy to take your bathroom for granted but, for many, indoor plumbing is a luxury they’ve simply never known. William Jacoby, associate professor of bioengineering at the University of Missouri, is part of a team focusing on supercritical water oxidation assistance. It may not bring everyone the ability to flush, but it aims to help developing countries that have challenges due to waste.

“The project is designed to treat the waste of 1,000 to 2,000 people and it can conceivably have a very small footprint to accomplish this,” says Jacoby, who is head of the Carbon Recycling Center lab at the university. His group was brought on the project by Duke University and the Gates Foundation. “On this scale, it’s going to be contained in a 20-foot shipping container that is being constructed as we speak,” he says.

The machine parts for the creation are made up of a flow reactor that relies on turbulent mixing. “That’s why it’s a classic example in the chemical engineering literature and this is an excellent application,” he says. “The design of a reactor is a well-understood issue and is being applied under relatively hostile conditions because pressure is high.”

Prof. William Jacoby and graduate students Nick Wilkinson, Malithi Wickramathilaka and Reza Espanani. Image: Jan Wiese-Fales /



The goal? With heat exchangers, the heat content of the waste material being burned in supercritical water provides the necessary energy to drive the process. Doing it effectively will take time but eventually these things could run without a plug, he says. “It’s a very flexible technology when you think about conventional combustion and air, so it can be applied to many things. The bottom line is if you do it right, it will release heat. The same is true when you think of combustion in this supercritical situation.”

Students have greatly benefited from the project. “They apply what they learn in school about kinetics and thermodynamics: heat, mass, and momentum transfer on the laboratory scale and now on the mobile pilot unit scale. This is a chance to reinforce their classes,” Jacoby says. “In that sense it’s a very good opportunity but, in a broader sense, serving their fellow human beings is what gets them really excited.”

One vital experience was when three members from Duke University and two from the University of Missouri in March attended the Reinvent the Toilet Fair in India. “We learned many things from it in principal, but most of all we learned that it’s hard to put a value on a machine that can make sludge disappear in a hurry. It’s exactly what they need in certain countries,” says Jacoby.

Reflecting further, he recalls a fateful train trip taken in India after the event: “I saw miles and miles of polluted river and people being forced to go to the bathroom in the open. Seeing mounds of waste that children are playing around really brought home what we’re working on. Nearly half the world has to live like this. No one should ever have to.”

Eric Butterman is an independent writer.

It’s a very flexible technology when you think about conventional combustion and air, so it can be applied to many things.

Prof. William Jacoby, University of Missouri


October 2014

by Eric Butterman,