CU-Boulder student investigates biochar for water treatment in developing countries

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Joshua Kearns

Graduate
PhD
Civil Engineering

A variety of public health issues plague the refugees from Burma living on the Thai border, not the least of which is drinking water contaminated by bacteria and pesticides. Yet, few low-cost, sustainable and appropriate treatment technologies are available to people in rural and developing communities to ensure water safety.

CU-Boulder doctoral student Joshua Kearns may have a solution involving a 4,000-year-old technology―filtering water through charcoal―made more robust through intensive research and development.

Kearns just returned from six months in Northern Thailand where he conducted field work on gasification methods for making sustainable, locally generated “biochar” from common agricultural residues such as corn cobs, sugar cane, bamboo and wood pruned from orchards.

Biochar is a kind of charcoal made from biomass sources, which is often added to soils to enhance their water and nutrient retention, and thereby increase crop yields. Carbonized biomass buried in soils is stable for hundreds to thousands of years, Kearns said, and if undertaken on a broad scale, biochar application can help to mitigate climate change by sequestering carbon. This fact has propelled biochar programs onto the agendas of governments, development agencies and NGOs worldwide in recent years.

Kearns believes that biochar also can be developed as a low-cost surrogate for commercial activated carbon to remove synthetic organic contaminants from drinking water through the surface binding process known as adsorption. His PhD work at CU-Boulder is focused on optimizing a process for heating biomass in small- to intermediate-scale gasifier devices, such as household cook stoves and farm-scale production units, to produce an effective char product with low emissions that is better than charcoal produced from traditional kilns.

“Nobody has studied this, and there are actually millions of people who could benefit from it,” says Kearns, a West Virginia native who holds a master’s degree in environmental chemistry.

Believing he has a moral obligation to follow through, and requiring state-of-the-art laboratory facilities and scientific mentoring to do so, Kearns went looking for a university where he could focus on low-tech, appropriate solutions for people in developing countries.

He says he found synergy with CU-Boulder’s Engineering for Developing Communities Program and the water quality work being done by Professor R. Scott Summers in the civil, environmental, and architectural engineering department. He also has been working with Professor Detlef Knappe at North Carolina State University as his co-advisor. Summers and Knappe are both widely recognized as world leaders in the field of activated carbon research and application in water treatment.

“I think we’re better positioned to look at how biochar could be used to improve water quality than anyone else in the world,” Kearns said.

Kearns has six years of experience working in Thailand to improve environmental systems. He went there to immerse himself in sustainable community development and founded the nonprofit, Aqueous Solutions, which consults on various projects to improve health and livelihood security in Southeast Asia through sustainable design and appropriate technology, particularly in the water-sanitation-hygiene (WASH) sector.

The Pun Pun Center for Self-Reliance in the Chiang Mai Province of Thailand provides a base for his experimental testing and other operations. Kearns was an intern at the Pun Pun farm in 2006, when he started to look at biochar as a low-cost water treatment alternative for people in rural Southeast Asia.

As part of this effort, Kearns has published a series of online handbooks and instructional videos on water treatment using biochar adsorbents. The materials are currently available at www.aqsolutions.org in English and Thai, and they are being translated into other Southeast Asian languages.

 “My philosophy is to empower people to use their resources sustainably and solve problems for themselves,” he said.

To date, Kearns’ work has been supported by the University of Colorado in the form of a Chancellor's Fellowship for Research, a grant from the Engineering Excellence Fund, and a Beverly Sears Graduate Student Grant. He also has received external support from the American Water Works Association, the iBoP Asia Partnership for Science and Technology Innovation, and the Charles A. and Anne Morrow Lindbergh Foundation.

In fall 2012, he begins a three-year tenure as a Science To Achieve Results (STAR) Research Fellow supported by the U.S. Environmental Protection Agency.

CU-Boulder student Josh Kearns attaches a data logger to monitor temperature inside the gasifier during biochar manufacture. Char quality for water treatment depends heavily upon achieving high temperatures (750-950 C) during pyrolysis. (Photo credit: Lyse Kong)
CU-Boulder student Josh Kearns attaches a data logger to monitor temperature inside the gasifier during biochar manufacture. Char quality for water treatment depends heavily upon achieving high temperatures (750-950 C) during pyrolysis. (Photo credit: Lyse Kong)
No smoke is emitted from the chimney of a gasifier when it is burning. Gasifier char production takes only two hours and emits far fewer atmospheric pollutants than traditional kiln methods, benefitting the respiratory health of local operators as well as global climate and air quality.
No smoke is emitted from the chimney of a gasifier when it is burning. Gasifier char production takes only two hours and emits far fewer atmospheric pollutants than traditional kiln methods, benefitting the respiratory health of local operators as well as global climate and air quality.
Jon Jandai of the Pun Pun Center for Self-Reliance assists CU-Boulder student Josh Kearns in removing the crown/chimney unit during shutdown of the gasifier. Once all the material in the drum has turned to char, the reactor is sealed to prevent entry of oxygen and allowed to cool.
Jon Jandai of the Pun Pun Center for Self-Reliance assists CU-Boulder student Josh Kearns in removing the crown/chimney unit during shutdown of the gasifier. Once all the material in the drum has turned to char, the reactor is sealed to prevent entry of oxygen and allowed to cool.
Jon Jandai and Josh Kearns seal the lid of the gasifier with mud to prevent entry of oxygen. The gasifier is left to cool for about 2 hours and then the char can be removed.
Jon Jandai and Josh Kearns seal the lid of the gasifier with mud to prevent entry of oxygen. The gasifier is left to cool for about 2 hours and then the char can be removed.

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