Using Nature to Clean Water

Dr. Renzun Zhao came to N.C A&T via a circuitous route compared to most. Zhao, an assistant professor who earned his PhD in Civil Engineering from Virginia Polytechnic Institute and State University, started his engineering career in private industry. Zhao worked for Veolia Water, the world’s largest supplier of water services with nearly 100,000 employees worldwide.

Renzun Zhao CroppedAccording to its website, Veolia’s mission is to resource the world, helping its customers address environmental and sustainability challenges in energy, water and waste. It strives to improve clients’ energy efficiency, better manage water and wastewater and recover resources from wastes. Zhao joined the company’s Cary, NC location in 2012 and worked for three years in the field, engineering full-scale water treatment solutions for Veolia customers.

“My industry experience has been invaluable because it keeps me rooted in the belief that good research can and should solve real world problems,” explains Zhao. “The research we did at Veolia resulted in valuable, marketable products and services that made a big difference to the facilities we supported.”

After a few years in industry, Zhao felt called to teach. With PhD and valuable industry experience in-hand, Zhao joined the faculty at Lamar University in Beaumont, Texas. He enjoyed interacting with students, and was able to demonstrate how what they were accomplishing in classes and labs translated directly into career opportunities. After a few years at Lamar, Zhao discovered a faculty opportunity at N.C. A&T in its Department of Civil, Architectural and Environmental Engineering. He was excited to join a larger institution with a renowned engineering program, and also appreciated the opportunity to return to North Carolina.

Zhao Lab Cropped

Students working in Zhao Lab. From left to right: Myles Greer (Sophomore, Civil Engineering), Harsh V. Patel (PhD student), Dr. Renzun Zhao, Raina Lenear (Senior, Civil Engineering).

After a very short time at N.C. A&T, Zhao received a positive response to his request for research funds. Waste Management, Incorporated, a comprehensive waste and environmental services company headquartered in Houston, provided Zhao with two research grants for $26,000 in 2019 and $46,000 in 2020.

The two grants, in series, are designed to minimize environmental impacts of landfill leachate, a waste liquid generated in municipal solid waste landfills. There are approximately 27 billion liters of landfill leachate produced each year in the United States, which eventually enters the water environment directly or indirectly. Treatment and management of landfill leachate can count for up to 33% of the operating cost of the solid waste management industry, the largest percentage of its expenses.

One aspect of environmental concern of landfill leachate is the emergence of PFAS, a large and problematic family of human-made chemicals that are found in a wide range of products used by consumers and industry. Many PFAS chemicals are resistant to grease, oil, water and heat which is going to make them very challenging to clean from the water supply. The work that Zhao and others are doing to cleanse landfill leachates will yield information and lessons to solve bigger problems down the line.

Another aspect of environmental concern is to sustainably eliminate excessive nutrients from landfill leachate. Discharge of nutrients, such as nitrogen and phosphorous, can cause eutrophication – excessive growth of algae that may result in dissolved oxygen depletion and eventually fish kill. Landfill leachate is a well-known nitrogen-rich liquid, 50 times more concentrated than sewage. Zhao has been investigating approaches to eliminate nitrogen from landfill leachate with microorganisms that are more efficient on energy use and chemical consumption during the treatment.

Zhao’s research findings, supported by the Waste Management Inc. grants, were recently presented at the 2020 Global Waste Management Symposium in California. He has a variety of research interests that have attracted undergraduate, masters and doctoral students to his lab: water/wastewater infrastructure, solid waste management, new emerging contaminants such as Per- and polyfluoroalkyl substances (PFAS), the water-energy nexus and infrastructure resilience.

Visit Dr. Zhao online at