Waste Disposal Technologies for Polychlorinated Biphenyls

Abstract

Improper practices in the disposal of polychlorinated biphenyl (PCB) wastes by land burial, chemical means and incineration distribute these chemicals and related compounds such as polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzodioxins (PCDDs) throughout the environment. The complete range of methods for disposal that have been proposed and are in use are examined and analyzed, with emphasis given to the two most commonly used methods: land burial and incineration.The understanding of aquifer contamination caused by migration of PCBs from subsurface burial sites requires a description of the physical, chemical and biological processes governing transport in unsaturated and saturated soils. For this purpose, a model is developed and solved for different soil conditions and external driving functions. The model couples together the fundamental transport phenomena for heat, mass, and moisture flow within the soil.To rehabilitate a contaminated aquifer, contaminated groundwaters are withdrawn through drainage wells, PCBs are extracted with solvents or activated carbon and treated by chemical, photochemical or thermal methods. The chemical and photochemical methods are reviewed, but primary emphasis is devoted to the use of incineration as the preferred method of disposal. After discussing the formation of PCDFs and PCDDs during combustion from chloroaromatic, chloroaliphatic, as well as organic and inorganic chloride precursors, performance characteristics of different thermal destructors are presented and analyzed. To understand how this information can be used, basic design equations are developed from governing heat and mass balances that can be applied to the construction of incinerators capable of more than 99.99% destruction with minimal to nondetectable levels of PCDFs and PCDDs.

Microbiology of Fed-batch Composting

“…Traditional composting processes or compost microorganisms have also been studied for bioremediation purposes. There have been several review papers concerning the application of composting technology to the bioremediation of soils contaminated with various pollutants including aliphatic and aromatic hydrocarbons 2,57,83) , nitroaromatic compounds 16,76,84) , chlorinated compounds 17,57,78) , pesticide 17,20) , diesel oil 21) and heavy metals 6) . The information accumulated in this field of research suggests that the FBC processes as well as conventional systems have potential applications to the bioremediation of polluted soil.…”

Combined strategy for the precipitation of heavy metals and biodegradation of petroleum in industrial wastewaters

“…1b). The reactor was prepared with 590 mL of mineral medium supplemented with a metal ion solution [(mg L −1 ): Cr 2 (SO 4 ) 3 , 60; CuSO 4 , 49; MnSO 4 , 50; ZnSO 4 , 80] with 2% (v/v) of petroleum and 2% (v/v) of a cellular culture in the exponential growth phase. The reactor was provided with an air inlet to allow aerobic conditions for cellular growth and also had temperature and pH sensors.…”

“…Many of these contaminants are toxic, mutagenic and carcinogenic, and they are persistent in the environment-thus presenting a significant hazard to ecosystems and human health [3,4]. The hazardous nature and persistence of these materials in the environment means that it would take decades to clean up such sites.…”