ORGANIC CONTAMINANTS AND ENVIRONMENTAL REMEDIATION

Organic Contaminants and Environmental Remediation



Outline

Introduction

Soil Remediation Technologies

Ecology

Meteorology and the Atmospheric Sciences

Environmental Chemistry

Geology and the Earth Sciences

Physical and/or Chemical Methods

Biological Methods

Thermal Methods

Water Remediation Technologies

Chemical and/or Physical Methods

Biological and Thermal Methods

Ecological and Health Issues Introduced by Remediation

Regulatory Framework

Detailed Outline in AppendixOrganic Contaminants and Environmental Remediation

Introduction

Environmental remediation is a process that aims to remove or reduce the levels of contaminants in soils, groundwater, surface water, air, or other environmental media in order to improve ecological or public health and/or facilitate the redevelopment of a contaminated site. A number of remediation technologies have been developed, some of which are routinely used and others that require further testing for effectiveness in the field. Although remediation is necessary to improve environmental conditions, there may be risks associated with environmental remediation, including the generation of secondary waste streams, the risk of future leaching for contaminants that were immobilized but not degraded, or the emissions of harmful particulate matter. The United States and Europe have implemented various regulatory and statutory approaches to facilitate the environmental remediation of contaminated sites.

Examples of situations that require remedial actions for environmental restoration include chemical and petroleum spills, abandoned landfills and industrial properties, and nuclear waste. Hazardous substances that may occur in contaminated sites include organic pollutants, such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and petroleum hydrocarbons, heavy metals (e.g., mercury, arsenic, copper, lead), radioactive materials, and pesticides (Whitney, 2003).

Remediation technologies can be biological, physical, chemical, or thermal and can degrade, contain, or chemically convert contaminants to less toxic or more easily extractable compounds. Physical and chemical mechanisms will often occur together in the remedial process. Furthermore, environmental remediation technologies can be carried out in situ or ex situ. In situ refers to the treatment of contaminants at their site of occurrence (e.g., injecting products into the subsurface to remediate groundwater), while ex situ refers to the removal of contaminated material to another location for treatment (e.g., pumping contaminated groundwater to the surface and treating in an aboveground reactor). Some remediation technologies can be applied either in situ or ex situ. Ex situ treatments are generally more expensive but faster, while impediments to in situ treatments include difficulties with the delivery of treatment to the contaminated site, uncertainties surrounding their effectiveness, and potential residual liability issues (Hamby, 1996).

Soil Remediation Technologies

Soil remediation methods include excavation, bioremediation, incineration, thermal desorption, soil washing, and immobilization technologies (i.e., that limit the leaching of contaminants from media), such as the encapsulation of wastes into cements or asphalt or in situ vitrification (Wilson, & Jones, 1993). Limitations to the use of soil remediation technologies might result from potential solubility or stability issues, and a dependency on particular environmental conditions or soil parameters, such as pH requirements. As a result, the performance of remediation may be difficult to predict, underscoring the importance of pilot studies, comprehensive sampling and modeling, and ongoing monitoring as part of the remedial process.

Ecology

The study of ecosystems—of populations of plant and animal organisms and their relationship to their environment—ecology grew ...