Thermal desorption for POP removal
OHM Remediation Services Corp., the United States, offers a patented thermal desorption process for removing organic contaminants from soils, sludges and other solid media. X*TRAX is neither an incinerator nor a pyrolysis system. Chemical oxidation/reactions are prevented by maintaining an inert environment and low treatment temperatures. Organic contaminants are removed as a condensed liquid, which is characterized by a high heat rating. This liquid may then be destroyed in incinerators or used as a supplement fuel.


In the new technique, an externally fired rotary drier volatizes water and organic impurities from the polluted media into a inert carrier gas stream. The nitrogen carrier gas transports water vapour and organic contaminants out of the drier. The carrier gas flows through a duct to the gas treatment system, where organic vapour, water vapour and dust particles are removed and recovered. The gas first passes via a high-energy scrubber, which removes dust particles and 10-30 per cent of the organic contaminants. The gas then passes through two condensers in series, where it is cooled to less than 5C.


Most of the carrier gas is reheated and recycled to the drier. About 5-10 per cent of gas is separated from the main stream, conveyed through a particulate filter and carbon adsorption system, and then discharged to the atmosphere. This discharge allows addition of make-up nitrogen to the system, to keep oxygen concentrations below 4 per cent. Also, the discharge helps maintain a small negative pressure within the system and eliminates leakage of potentially contaminated gases. The volume of gas released from this process is about 700 times less than from an equivalent capacity incinerator.


Contact: Mr. Chetan Trivedi, OHM Remediation Services Corp., 100, West 22nd Street, Suite 101, Lombard, Illinois 60148, the United States. Tel: +1 (630) 2613 958; Fax: +1 (630) 2613 969.


Website: www.clu-in.org 
Anaerobic bacterium degrades dioxins
Researchers at Martin-Luther-Universitat Halle-Wittenberg, Germany, have uncovered that an anaerobic bacterium known to degrade chlorobenzenes can break down dioxins also, including extremely hazardous congeners. The team isolated bacterial strains from sediments fouled with dibenzofurans and polychlorinated dibenzo-p-dioxins using polymerase chain reaction. Among bacterial strains that exhibited the ability to dechlorinate dioxins, two strains belonged to the genus Dehalococcoides. One of the strains, CBDB1, is the only known bacterium for dechlorinating chlorobenzenes and the other strain has been shown to convert tetrachloroethane to ethene.


Researchers have established that Dehalococcoides is indeed involved in dioxin dechlorination by studying the capability of CBDB1. They found that CBDB1 can transform several noxious dioxin congeners into less harmful ones, even without the addition of chlorobenzenes, indicating that the bacterium can use dioxins as respiratory electron acceptors. Results suggest that microbes of the Dehalococcoides cluster could be useful in bioremediating dioxin-contaminated sites.


Website: www.pubs.acs.org 
Disposal of polychlorinated biphenyls
Mitsubishi Heavy Industries Limited (MHI), Japan, has developed technology to dispose polychlorinated biphenyls (PCBs). The new hydrothermal decomposition procedure eliminates PCBs without forming harmful by-products. Hydrothermal decomposition occurs under high-temperature, high-pressure water. 
Crystals of sodium carbonates form under this condition and its surface- active sites remove chlorine from 


PCBs. PCB is then oxidized into harmless compounds such as water, sodium chloride and carbon dioxide. MHIs PCB total processing system, approved by the Ministry of Health and Welfare, integrates the hydrothermal decomposition and cleaning of contaminated containers.

Advantages of MHIs PCB total processing system include:
  • Selecting appropriate cleanser: PCB contaminated containers canbe treated using either organic and/or cheap aqueous surfactant solutions, depending on the dirtiness of the object to be cleaned. The containers can be recycled as a material after optimized use of cleanser selection;
  • Application over a wide range of PCB concentration: The same equipment can be used for low to high concentration of PCBs by changing residence time in the reactor;
  • No formation of corrosive compounds: Reliability of equipment is high without corrosive compounds like hydrogen chloride, etc.;
  • Treatment of PCB contaminated paper and wood: Paper, wood, etc. can be slurried and decomposed by hydrothermal decomposition. Additionally, activated carbon and wastes can also be treated; and
  • Decomposition of other organic compounds: Organic impurities that are difficult to dispose off through incineration e.g. cleansing solvent, waste paint, waste fuel, etc. can be easily decomposed.


Contact: Mitsubishi Heavy Industries Ltd., 2-5-1, Marunouchi Chiyoda-ku, Tokyo 100 8315, Japan. Tel: +81 (3) 3212 3111; Fax: +81 (3) 3211 9800


Website: www.mhi.co.jp 
Website: www.nett21.unep.or.jp 
Treatment of PCBs
Material Resource Recovery, based in Canada, offers thermal oxidative process to degrade polychlorinated biphenyls (PCBs). The new system consists of a primary combustion chamber, a secondary combustion chamber (afterburner) and a Venturi and packed tower scrubbing system. PCB materials are placed inside the primary chamber where initial combustion takes place at temperatures of 400-1,000C. All the combustion gases enter the secondary chamber where complete combustion occurs at a minimum of 1,200C. Gases exiting the secondary chamber are passed through a venturi and packed tower scrubbing unit where acidic gases are neutralized and removed.


The destruction/removal efficiency of the process is more than 99.9999 per cent. It complies with all provincial and federal regulations. 


Contact: Material Resource Recovery, P.O. Box No. 683, 2425, Industrial Park Road, Cornwall, Ontario K6H 5T5, Canada. Tel: +1 (613) 9387 575; Fax: +1 (613) 9380 660.


Website: www.mrri.com 
On-site remediation of groundwater
ManTech Environmental Corp., the United States, is offering CleanOX technology for in situ remediation of organic pollution in groundwater and saturated soils, including fuels, solvents, pesticides, etc. The new patented process reduces groundwater contaminants into harmless carbon dioxide and water through an injection method that is significantly cheaper than conventional remediation techniques. Proprietary liquid chemical formulations are injected through monitoring wells into the befouled part of an aquifer. Immediate reductions in the concentration of the following contaminants is feasible: aromatic compounds (BTEX), nitro-aromatic compounds, chlorinated solvents, polychlorinated biphenyls, alcohols (phenols), total petroleum hydrocarbons, polynuclear aromatic hydrocarbons, organic pesticides and mineral oil products.


CleanOX involves the application of a Fenton-like chemistry to create and migrate hydroxyl radicals, which in turn degrade organic impurities into carbon dioxide and water. The technology can be used to set up natural attenuation, source control/removal, hot spot treatment, speedy groundwater treatment, as well as augment existing processes such as SVE/sparging units, groundwater pump and treat, in-well stripping and phytoremediation. Key benefits offered by CleanOX are:
  •  Contaminant reduction in weeks to months;
     
  • Mobile in situ treatment system that has limited disruption to on-site operations;
  •  The reagents are applied through two-inch diameter monitoring wells;
  •  Applied under buildings and within operational areas;
  •  Requires no capital equipment purchase; and
  •  Eliminates long-term operation and maintenance costs.

Contact: ManTech Environmental Corp., 14290, Sullyfield Circle, Suite 100, Chantilly, VA 20151, the United States. Tel: +1 (703) 8148 366; Fax: +1 (703) 3783 396


Website: www.cleanox.com  
Website: www.environmental-expert.com