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Nadia Riis Thorius Feb 13, 2020

The PI System helps Duke University take up the reinvent the toilet challenge

Toilet water at Duke University

Despite progress on the United Nations' Millennium Goal to improve sanitation worldwide, 800,000 children under the age of five die each year from diarrhea, pneumonia, and other common infections caused by unsafe water. Today, a third of the world's population uses unsafe sanitation facilities that can put them at risk and allow human waste to mix with drinking water sources. To combat this massive problem, in 2011 the Bill & Melinda Gates Foundation launched the “Reinvent the Toilet Challenge,” a philanthropic initiative to bring sustainable sanitation solutions to the 2.5 billion people worldwide who don't have access to safe, affordable sanitation.

Since the Foundation's introduction of the Toilet Challenge, leading engineers and scientists have undertaken several research projects to address sustainable sanitation. One of them is taking place at Duke University in Durham, North Carolina. The university's solution is a neighborhood-scale fecal sludge processing system that provides human waste treatment in a decentralized way. The envisioned full-scale systems would serve communities of 6,000 or 30,000 people. Their current prototype is installed in a 20 ft. shipping container that might just be world's smallest treatment plant. It is sized to treat the waste of around 1,200 people. The unit relies on OSIsoft's PI System to collect and analyze real-time data and optimize research operations.

The Supercritical Water Oxidation Lab

Created by engineers at Duke's Civil & Environmental Engineering Department, the prototype utilizes a process called supercritical water oxidation (SCWO), which is a viable alternative to traditional sewer and fecal sludge treatment. “Supercritical water oxidation is a high temperature, high pressure process. It's like a pressure cooker on steroids,” explains Marc Deshusses, Professor of Civil and Environmental Engineering, who leads the project together with Kobe Nagar, its Principal Engineer. “The pressure is 240 times the atmospheric pressure. At these conditions organic matter and fecal waste burn extremely fast. In around four seconds, we go from fecal waste to carbon dioxide and water.” 

The byproducts of the treatment are clean water which can be processed further into drinking water, carbon dioxide as well as inorganic minerals, which can be utilized as fertilizers. “The chemically aggressive conditions allow us to breakdown the toughest organic molecules like plastics and pharmaceuticals very quickly and process high throughputs in a very compact footprint,” explains David Ballenghien, a Research Associate at the SCWO Lab. “The continuous process utilizes the energy embedded in the waste, thus enabling the units to operate off-the-grid while increasing the system's resiliency.”

The Data-Driven Research Project

The team's pilot project is highly iterative. It requires understanding the system in real time, experimenting, analyzing the data, and optimizing the system to continuously improve it - a process that heavily relies on operational data.

“Data analysis is of paramount importance, as it helps the engineering team increase its understanding of the process and events and gain confidence in the conclusions that are drawn,” Ballenghien says.   

Initially, the team had to manually import and export CSV files with all the different sensors in the system and searched for ways to simplify unit operations. They wanted a tool that would make it easy to quantify and benchmark performance of the pilot. Their answer was the PI System, which thanks to OSIsoft's Academic Program came with a complementary license for use in research. Relying on the PI System, the team quickly gained real-time insights into unit operations. They can easily access and analyze historical data sets, identify specific process events, and keep a relevant record of research. Using OSIsoft's Asset Framework (AF), the contextualization layer of the PI System, researchers were able to create a unified data model of all equipment parameters, such as water temperature, pressure, and flow inside the unit. Engineers created PI Vision dashboards to monitor operations in real time using simple, web-based displays. 

“The PI System has made it easier and more comfortable to operate the system and monitor live trends and KPIs,” Ballenghien explains. “It helped us make better use of our process data, allowed us to revisit older data sets, and made it simpler to store and access all the data in the same place. Overall, it was a great gain for our team's productivity.”

Find out more about Duke's Supercritical Water Oxidation Lab here

Nadia Riis Thorius Marketing Content SpecialistNadia Riis Thorius is a Marketing Content Specialist at OSIsoft.
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