Ronald R. Hewitt Cohen

Emeritus Associate Professor

I have had an interest, since the early 1990s, in the development and optimization of microbiological treatment systems for mine drainage and other, metal and acid laden waste streams. This interest started with improving passive, sulfate reducing bacteria (SRB) dominated, bioreactor-based, metals treatment systems – also called wetland treatment systems. These interests have lead to further efforts focused on Mining and the Environment. I have lectured on biological treatment of mine wastes, uranium remediation, tailings disposal, and environmental chemistry of mine wastes and cyanide in South Africa, Mali (West Africa), India, Brazil and England. In 2002 and 2003, I was part of an international team doing environmental audits of 3 gold mines in Mali. I was responsible for the environmental issues including water and cyanide use and disposal, hydrocarbon pollution, cyanide-in-pulp and cyanide heap leach processes, and chemical and hydrocarbon storage. Most of my summer of 2007 and the late summer and fall of 2008 were spent working on uranium and arsenic remediation in the major gold mining region of South Africa.

Another focus has been on the use of geochemical models to identify subsurface transport of metal contaminants. We (the ‘we’ includes graduate students) successfully have used the technique to determine metal contaminant pathways from mine workings in the mountains of Colorado, to a point in a stream just above a trout fish hatchery. Routine groundwater test methods were not successful in identifying the complex, fractured rock pathway.

Related to the microbial treatment processes have been our studies on the removal from waste streams not only of the positively charged, cation metals, but also the metals that exist as oxyanions (associated with oxygen and appearing as negatively charged anions) – like arsenate and chromate. We have been successful in removing, inexpensively, metal oxyanions from waste streams. We also have publications on the impact of pH, redox potential and sorption processes on effectiveness of passive bioreactors on treatment of mining impacted waters.

In 2004, I had the unique experience of going to Nepal and working with faculty and administrators of Tribhuvan University to development an Environmental Engineering curriculum for their Institute of Engineering. I also worked on remediation of arsenic pollution in Nepal. Additionally, in that area of the World, I have offered short courses in Mining and the Environment in New Dehli, India.

I have been contracted by the National Nuclear Regulator (NNR) of South African Government to characterize and evaluate uranium and daughter product contamination in the gold mining regions of the Far West Rand and recommend remediation strategies for the mitigation of the contamination (2007, 2008, 2009).

I am thrilled with the official recognition of my work. I am the recipient of a Certificate of Special Recognition from the U.S. Congress for environmental work associated with the Dept. of Energy Nuclear Weapons Plants. I was selected, by the Secretary of Energy’s staff, to review the National Five Year Plan for Environmental Remediation of the National Nuclear Weapons Plants. In 1991, I shared in the 1st Prize for Environmental Projects from both the Colorado and American Consulting Engineers Council for work with acid mine drainage treatment bioreactors. Even more exciting is twice receiving the Outstanding Professor of the Year award from the Minority Engineering Program and being honored as the Graduating Seniors’ Outstanding Professor of the Year award for the 1996 through Spring 2008 academic years.