It was 1962 and the industrial age was at its apex. America’s factories churned out countless consumer goods. Cities swelled. Petroleum was cheap and plentiful. The world put its faith in better living through chemistry. But progress came at a cost. Air, land and particularly water were growing toxic. That year Rachel Carson published her canary-in-a-coal-mine environmental treatise, Silent Spring.
It was also in 1962 that Perry McCarty first came to Stanford, looking for a different focus on a field then known as sanitary engineering. As McCarty recalls, his family didn’t understand what he had studied: “They said, ‘You’re getting a PhD to become a garbage man?’”
Fast-forward 50 years and McCarty is widely regarded as one of the founders of the discipline now known as environmental engineering.
In recognition of this and other accomplishments, Perry McCarty will become the latest “Stanford Engineering Hero,” taking his place alongside William Hewlett and David Packard, Frederick Terman and Sally Ride, Sergey Brin and Jerry Yang, and other exemplars of Stanford Engineering.
While his human collaborators are legion, McCarty would say that he owes his career to bacteria, and a particular variant of microbes that can’t survive in an oxygen environment – hence their name, anaerobic bacteria. One anaerobe of importance in groundwater cleanup has been named after him, Dehalococcoidesmccartyi.
One of the most significant accomplishments of McCarty’s career is his role in discovering that, given enough time and protected from oxygen, these microbes can digest just about anything. That makes them incredibly useful to environmental engineers because they can cleanse water or soil of many manmade chemicals once thought untreatable – industrial chemicals, insecticides and pesticides including DDT, the effects of which inspired Carson to write Silent Spring.
In his oral history, McCarty recalls the day that a student, Dave Hill, brought data samples that showed how DDT and lindane, a widely used insecticide, disappeared during anaerobic processing. “I said, ‘It can’t disappear.’ He went down and did it again and they disappeared,” McCarty recalls. “We published a paper in 1968, the first-ever reductive article. It shows all the pesticide compounds anaerobically disappear within days.”
Over time McCarty and successive cohorts of students codified or created from scratch the mathematics that environmental engineers would use to design biological treatment facilities. He united stoichiometry and energetics – measuring the amount of materials and energy needed in a given reaction – to understand and transform bioreactor designs.
In the mid-seventies, McCarty introduced gas chromatography and mass spectrometry into his research. Engineers could now readily identify the specific compounds in a sample. The advance produced a revolution in groundwater reclamation at Superfund sites like Love Canal, a former chemical dump turned housing subdivision. “We were way out in front of knowing by looking at all the compounds in groundwater and developing models,” McCarty says.
Craig Criddle, a former student of McCarty’s who now serves as professor of environmental engineering at Stanford, explains: “Perry established the mathematics on growth and decay. How much biomass they’ll produce. How much energy they’ll consume – everything.”
By his retirement in 1999, McCarty had trained 40 PhD students, half of whom went on to teach at universities. Of these, 11 became department chairs and one, a dean. He has authored some 350 peer-reviewed papers. His textbooks Environmental Biotechnology – Principles and Applications and Chemistry for Environmental Engineering and Science (co-authored with former students Bruce Rittmann of Arizona State University and Gene Parkin of the University of Iowa) have together sold over 200,000 copies and are the standard texts for a profession that would counteract and mitigate the environmental degradation, pollution and waste of the industrial age.
Over time, McCarty has been showered with awards and accolades, including memberships in the American Academy of Arts and Sciences and the National Academy of Engineering, and winning the Tyler Prize, the Clarke Prize and the Stockholm Water Prize – three of the most-respected awards in environmental sciences. “He has advanced environmental engineering and science as no other. As a student, I got big ideas about what we could do from Perry McCarty,” says friend and colleague Dick Luthy, who holds the Silas H. Palmer Professorship at Stanford that McCarty occupied for decades.
Following his official retirement, McCarty continued as a researcher and consultant. In 2009, he began a five-year stint in South Korea to teach and conduct research toward anaerobic treatment of domestic wastewater with former student Jaeho Bae. The relationship resulted in pilot studies of a new treatment system known as the anaerobic fluidized-bed membrane bioreactor, a design that has since been duplicated elsewhere, including on the Stanford campus at the William and Cloy Codiga Resource Recovery Center.
McCarty continues to advise Sebastien Tilmans, a former student of Criddle’s who manages Codiga as a proof-of-concept facility, producing a thousand gallons of reusable-though-nonpotable water each day. Codiga also converts waste organic matter into valuable soil amendments, bioplastics and even animal feed supplements and yields methane that fuels the plant.
Codiga represents the forward spin on one of McCarty’s lifelong beliefs – to see the potential for reuse in what other see as refuse. At Codiga some of the biological processes that he helped pioneer are now used to return wastewater – what he insists on calling “used water” – to everyday use after removal of an array of pollutants and hazardous chemicals, including pesticides, pharmaceuticals and poisonous heavy metals.
McCarty continues his research to this day, ever curious, ever intent on solving the challenges of clean water for a rapidly changing world – a true Engineering Hero.
In his Hero lecture, delivered at the Stanford School of Engineering on October 18th, 2016, McCarty discussed his life’s work examining how microbes provide unique solutions to environmental problems.
For more about Professor McCarty's career please visit his two-part oral history, in 90-minute and 50-minute segments in which he is interviewed by Andy DiPaolo on behalf of the Stanford Historical Society.