Kevin W. Biggar

Bioremediation of DDT-Contaminated Soils: A Review

The insecticide 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)ethane (DDT) has been used extensively since the 1940s for control of agricultural pests, and is still used in many tropical countries for mosquito control. Despite a ban on DDT use in most industrialized countries since 1972, DDT and its related residues (DDTr) persist in the environment and pose animal and human health risks. Abiotic processes such as volatilization, adsorption, and photolysis contribute to the dissipation of DDTr in soils, often without substantial alteration of the chemical structure. In contrast, biodegradation has the potential to degrade DDTr significantly and reduce soil concentrations in a cost-effective manner. Many bacteria and some fungi transform DDT, forming products with varying recalcitrance to further degradation. DDT biodegradation is typically co-metabolic and includes dechlorination and ring cleavage mechanisms. Factors that influence DDTr biodegradation in soil include the composition and enzymatic activity of the soil microflora, DDTr bioavailability, the presence of soil organic matter as a co-metabolic substrate and (or) inducer, and prevailing soil conditions, including aeration, pH, and temperature. Understanding how these factors affect DDTr biodegradation permits rational design of treatments and amendments to stimulate biodegradation in soils. The DDTr-degrading organisms, processes and approaches that may be useful for bioremediation of DDTr-contaminated soils are discussed, including in situ amendments, ex situ bioreactors and sequential anaerobic and aerobic treatments.

Trickle-freeze separation of contaminants from saline waste water

This study investigated the feasibility of using trickle-freeze separation as an alternative method of reducing the salinity of oil sands process water. Using a specially designed flume housed in a cold room, an experiment was conducted to determine the degree of separation and subsequent concentration of salts during freezing and melting of saline water. During the freeze – thaw cycle, the majority of salts were concentrated into less than one quarter of the original frozen volume. Utilizing results from the laboratory-scale experiments, a trickle-freeze separation system was designed to treat 20 million m3/year of saline process water. The capital investment for construction of the system was Can

Geotechnical Virtual Laboratory. I. Permeability

127 million or Can

Horizontal sampling: A new direction in site characterization

6.36/m3 capacity, slightly higher than for a conventional desalination processes. Annual operating costs of Can

Groundwater Geochemical Characterization of a Fuel-Contaminated Fractured Bedrock in a Permafrost Environment

0.13/m3 of waste water are significantly lower than for conventional desalination. The design and cost estimate provided insight into the feasibility of using trickle-freeze separation as a treatment option for oil sands process water.

The Geotechnical Virtual Laboratory. II. Consolidation

The Geotechnical Virtual Laboratory is a computer based instructional package intended to complement, and potentially replace, some physical testing in a real geotechnical laboratory. The article covers initial design stages of the project, mostly work on the first (permeability) module, its outcomes, evaluation results, and the experience in its use.

Potential for bioremediation of petroleum hydrocarbons in groundwater under cold climate conditions : A review

Traditionally, sampling and monitoring of potentially contaminated soils and ground water has been achieved using vertical drilling technology. However, vertical drilling presents several technical limitations, including the need to position the drilling rig directly above the target zone and the risk of cross-contaminating laterally stacked aquifers. These limitations may be overcome using horizontal directional drilling technology. This paper gives a short introduction to horizontal directional drilling equipment and installation techniques, followed by an overview of existing horizontal sampling tools. Details for the development of a horizontal multiple port soil sampler are outlined and the future role of horizontal sampling in site investigation is discussed. It is concluded that horizontal directional drilling technology has many applications in site investigation, offering an efficient and cost-effective method of collecting geotechnical and geo-environmental data, both as an alternative and as a complement to vertical drilling and sampling technologies.

SITE INVESTIGATIONS OF FUEL SPILL MIGRATION INTO PERMAFROST

AbstractRemediation of a contaminated site to site-specific cleanup standard requires a good understanding of the geochemical characteristics of the site. In this study, the groundwater hydrochemical characteristics of a fuel-contaminated mine site in the Northwest Territories (Canada) was evaluated to understand the active geochemical processes and assess the groundwater quality in comparison to guidelines for the protection of freshwater aquatic life. Groundwater samples were taken from installed monitoring wells across the site and analyzed by field and laboratory methods for dissolved metals; ions; and benzene, toulene, ethylbenzene, and xylenes (BTEX) organic constituents. The results showed that the groundwater is Ca-SO4 type because of ubiquitous occurrence of gypsum dissolution and carbonate weathering. The last sampling at the site showed that the BTEX constituents of interest were above the guideline limits in some locations, but other geochemical indicators showed biodegradation is occurring at...

Laboratory investigation on freeze separation of saline mine waste water

The Geotechnical Virtual Laboratory is a computer based instructional package intended to complement, and potentially replace, some physical testing in a real undergraduate geotechnical laboratory program. It was described in an earlier paper published in this journal. This article describes the second module, which covers consolidation phenomena and oedometer testing.