Methods and technologies of disposal of poly-chloride biphenyls in transformer oils
A review of the main methods of disposal of waste containing polychlorinated biphenyls (PCBs) is presented. It is shown that a reliable, environmentally friendly and efficient process does not exist, and, apparently, it is impossible to create a completely environmentally friendly process. Analysis of the benefits and advantages of technology suggests that the best method in view of ecological and economic reasons is a method of processing PCBs with sodium - simple technologically process takes place at normal temperatures, does not require large capital investments, but the conditions of storage of metallic sodium - necessarily under oil layer- must be respected. In the last 30 years of focus group analysis of persistent organic pollutants (POPs) that affect the environment at an extremely low level (lower detection limit is 1081013 %) to the beginning of the 70ies of the last century there have been produced more than 2 million tons of various kinds of materials containing polychloride biphenyl (PCB). In a study of professional and household statistics of diseases and its reasons, it was found that PCBS or arochlor (chlorinated diphenyl) is dangerous to human health, causing the destructive effects on the hormonal system. Many of them have been known for a long time and have been widely used in industry and agriculture in most countries. Even a brief review of methods for decontamination of wastes containing PCB shows that reliable, environmentally friendly and cost-effective process does not exist and, apparently, it is not possible to create a completely ecologically safe process with 100 % conversion. Method of processing PCB waste with sodium is technologically simple and carrying under normal temperatures, it does not require large capital investments, but it is necessary to taking into account the storage metal sodium - only under a layer of oil. Advanced technology in one stage of dechlorination of PCB refers to non-waste processes, but the value of conversion should not exceed 80 % (determined by the level of sodium). Technology has the ability to manufacture mobile equipment and recovery of consumer properties of transformer oil. The estimated payback period is 1 year. An analysis of the benefits and advantages of the technology showed that the best of the ecologically efficient considerations is processing PCB waste. However, this technique requires improvement in the operation of metal sodium to disperse to 30 - 100 nm or less that would enhance the conversion of PCBS to 95 - 99 % at one stage. To achieve 99.99 % or higher conversions, the operation process should be performed with petroleum casing for enrichment of the mixture of hydrocarbon molecules of PCBs.