The Remediation Technology Summit

February 26-28, 2019

Colorado Convention Center
Denver, CO

duganPamela J. Dugan, Ph.D., P.G. 
Business Development Manager
Carus Corporation

Pamela serves as the Business Development Program Manager for Carus Corporation where she is responsible for new product and business development in the fields of environmental remediation and industrial water treatment. She has a B.S. from Indiana University a Ph.D. in Environmental Engineering from the Colorado School of Mines, and is a registered professional geologist. Pamela has over 15 years of remediation experience with particular focus on chemical oxidation, bioremediation, and metal removal technologies.

PLATFORM PRESENTER - Heavy Metal Bands and Other Ignoble Species: The Rock Stars

Heavy Metals Got You Down? Treatment Options for As, B, Hg and Se

Background/Objectives. Heavy metals such as Arsenic, Selenium, and Mercury as well as Boron are widely distributed and persistent pollutants in the environment. Although all contaminated sites are unique and a site-specific approach to remediation is often required, heavy metal contamination creates even more complex challenges. Remediation methods in general use include isolation, immobilization, toxicity reduction, physical separation and extraction. The ecological and human health effects of arsenic, mercury, and selenium are generally related to the environmental transformations. For example, inorganic mercury can transform to the more toxic monomethylmercury (MeHg) in anaerobic environments such as contaminated sediments. Biomagnification of MeHg in the aquatic food web and consumption of fish and shellfish contaminated with MeHg is the primary route of human exposure to Hg(II). MeHg is toxic to both humans and fish. Almost all mercury in fish is MeHg. MeHg is formed largely in anoxic sediments from inorganic mercury methylation mediated primarily by sulfate reducing bacteria. The bottom sediments are the main reservoirs of mercury and to the extent that this mercury is available to overlying water is a sensitive indicator of risk to the aquatic ecosystem. Effective remediation of such sediments to reduce the release of mercury is essential to minimize the contamination of fish and shellfish with MeHg. Boron is also an environmentally regulated substance and potentially phytotoxic if it is in a soluble state. It is well known to condense in the coal fly ash generated from coal combustion plants. Since boron in the coal fly ash tends to elute into the soil easily, a technology for its stabilization or removal from fly ash is required. Experimental results will be presented that demonstrate the efficacy of a number of adsorbents and an industrial waste byproduct for immobilization of As, B, Hg, and Se.

Approach/Activities. Batch and column experimental studies were conducted with iron and iron and manganese-based adsorbents as well as adsorbents obtained from industrial waste processes to investigate their ability to adsorb As, B, Hg, and Se from solution. Two industrial waste by-products and four adsorbents were characterized to understand the physical and chemical properties of the materials in terms of particle size and what compounds could be leached from the industrial waste by-products as part of toxicity characteristic leaching procedure testing. In addition to the adsorbents commercially available products (e.g,, PAC and ZVI) were used to compare removal performance.

Results/Lessons Learned. A laboratory investigation was conducted to assess the feasibility of immobilizing heavy metals using a number of reactive adsorbent materials. Preliminary batch sorption screening test results indicate 60%-100% of As, B, Hg, and Se were removed from aqueous batch reactors. Results regarding the ability of a variety of amendments and combinations of amendments to immobilize metals as a function of metal concentration and mass of adsorbent will be presented as well as results from 1-D flow-through column tests evaluating As removal efficiencies as a function of pore volumes flushed.