Chlorinated organic remediation

Methanotrophic biofilters are a biological technology for remediation aqueous- and liquid-phase organic contaminants, particularly chlorinated organics. This technology utilizes a type of bacteria, known as a methanotroph, that consumes methane as a nutrient source. 

Dehalogenation occurs by either the replacement of halogen molecules or the destruction of the contaminant. Soil and sediment that are contaminated with chlorinated organic compounds, especially PCBs, dioxins, and furans, can be remediated through dehalogenation. The contaminated soil is screened, processed with a crusher and pug mill, and mixed with sodium bicarbonate. The mixture is heated to above 330°C (630°F) in a reactor to partially decompose and volatilize the contaminants. The volatilized contaminants are captured, condensed, and treated separately. 

Zero-valent iron is a promising in situ remediation technology for the degradation of many common pollutants, as it is comparatively inexpensive, does not restrict land use, and requires no energy for operating. Zero-valent iron has been successfully utilized to destroy trichloroethenes, chromate, chlorinated organics, and mixed wastes. It is capable of reducing and... 

Dechlorination occurred in parts of the soil column where reducing conditions (Eh-pH conditions) are dominant. The most significant reductive dechlorination of TCE occurred near the cathode, a source of electrons during electroosmosis. Results show the need to include a decay term in the transport equations. The results show that potential chemical transformation of chlorinated organic compounds could enhance the remediation efficiency during EO. 

Gillham RW. In situ treatment of groundwater metal-enhanced degradation of chlorinated organic contaminants. Recent Advances in Ground-Water Pollution Control and Remediation, NATO Advanced Study Institute, Kemer, Antalya, Turkey. New York Kluwer Academic, 1996 249-274. 

Keywords Natural attenuation Hysteresis Adsorption Desorption Biodegradation Kinetics Remediation Chlorinated organics Partition coefficients... 

To reduce production of chlorinated organics during bleaching, the pulp and paper industry has replaced chlorine with chlorine dioxide. Chlorine dioxide or its primary precursor, sodium chlorate, can be produced by the low-tonnage chlorine industry with the same hardware that is used for synthesis of chlorine and hypochlorite. This simple transition from chlorine to chlorine dioxide synthesis may be the reason for the less-than-anticipated usage of hydrogen peroxide in the pulp and paper industry. Increasing use of chlorine dioxide could also lead to its applications in other effluent treatment areas such as industrial wastewater remediation. 

Chlorinated organic compounds (COCs) refer to the substitution of one or more hydrogen in aliphatic and aromatic hydrocarbons and their derivatives by chlorine. COCs are widely used in the fields of chemistry, medicine, electronics, pesticides, etc. Many COCs are endocrine disturbance substances, show carcinogenic effects, and have been listed as priority pollutants by the US Environmental Protection Agency (USEPA). When released into the environment, COCs are transported in both air and water. However, COCs are chemically stable and difficult to destroy, and they are eventually deposited in soils and sediments due to their hydrophobic-ity. Soils and sediments contaminated with COCs are long-term sources of pollutants and pose great threats to human health and ecosystems. Therefore, remediation of these contaminated soils and sediments is of great importance. 

Chang JH, Qiang ZM, Huang CP. (2006). Remediation and stimulation of selected chlorinated organic solvents in unsaturated soil by a specific enhanced electrokinetics. Colloids and Surfaces A 287 86-93. 

Remediation of chlorinated organic compounds by using conventional electrokinetic method is limited because of the limitations of caused by desorption and solubilization. These compounds bind strongly to the soil organic matter. Therefore, very low aqueous phase concentrations are reached at equilibrium. Furthermore, low solubilities of HOCs limit the concentrations in water. Therefore, either... 

Despite the research progress mentioned above, none of the above techniques has been widely adopted commercially for environmental remediation applications due to one or more limitations of each method. For example, incineration of concentrated chlorinated organic compounds requires special treatments to remove the HCl generated. HCl corrodes the equipment if not removed. In addition, incineration of PCBs and other chlorinated organics often produces more toxic compounds (e.g. dioxins) if it is not carefully controlled. Thus, Erickson et al (87) reported that combustion of PCBs leads to the formation of small amounts of the most highly toxic polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzodioxins (PCDDs). Moreover, disposal of chlorinated solvents, neat PCBs, and related chemicals by... 

The third section of this monograph also covers some other representative recent research to develop new remediation options. When an aquifer or soil is contaminated, careful site characterization must be integrated with the remediation design to clean the site. This is the topic of Chapter 22 by Reeves and coworkers. Chemical reductions are the topic of Chapter 23 by Farrell al and Chapter 25 by Pittman et al. Passing water from a contaminated plume over a bed of finely divided iron to remediate contamination from chlorinated organics has recently attracted significant attention. A consideration of the mechanisms controlling process is provided by Farrell. 

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