Engineering researchers at Texas A&M University have developed a first-of-its-kind water monitoring technique that improves flocculation and minimizes the energy used for mixing.
Coagulant chemicals are typically added to purify drinking water, remove turbidity and microscopic pathogens. They form large clumps called flocs that can easily be filtered out. The new method simultaneously monitors the size and shape of floc clumps and the mixing intensity in a single step, in real time, allowing for more accurate measurements, and the ability to successfully remove contaminants by growing large enough clumps with less energy expended.
The new technique allows researchers to monitor this key process of water treatment in real time.
“All previous research did this in two steps,” explained Dr. Kuang-An Chang, professor in the Zachry Department of Civil and Environmental Engineering at Texas A&M, in an announcement from the university. “In the old approach, first, artificial particles of known characteristics would be added to monitor mixing. Then, a second experiment would be done with ‘identical’ settings and the actual clumps would be monitored,” he added.
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Mixing is one of the most energy-intensive processes during water and wastewater purification, said Chang. The new technique non-intrusively monitors the mixing to precisely control it. Chang noted that it is crucial to properly mix the water and chemicals so the pathogens properly clump. If mixing is low, clumps won’t form. If mixing is too intense, clumps will form but quickly break apart.
The new techniques also allow researchers to quantify heterogeneities within the reactor, and potentially optimize it to create flocs of desired characteristics, said Chang.
“We essentially halved the workload and improved precision because there are always statistical differences any time you do two experiments,” said Chang.
The interdisciplinary project was a collaboration between Chang, who focuses on fluid dynamics, and Dr. Shankar Chellam, a professor of civil and environmental engineering, who focuses on water and wastewater treatment.
Three graduate students performed the experimental work and associated numerical analysis: Kaleisha Miller, Kyungho Kim and Wei-Liang Chuang, who is now an assistant professor at National Sun Yat-sen University in Taiwan.
This article appears in ES&E Magazine’s April 2023 issue: