الفهرس 
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Abstract
Polychlorinated biphenyls (PCBs) from a group of persistent organic pollutants (POPs) of the environment, especially dangerous to living organisms due to high toxicity, chemical stability, and absorbed in adipose tissue. Despite of this fact, PCB-contaminated oils are still commonly encountered partly because PCBs used as cooling oils in transformer and capacitors. PCBs contamination of the environment is occurred due to the re-use for purposes other than their allocated.
PCBs were leaking from transformers and had contaminated the soil at the bottom of utility poles. Concern over the toxicity and persistence (chemical stability) of PCBs in the environment. PCBs in soil are unlikely to migrate to groundwater because of strong binding to soil. Volatilization from soil appears to be an important loss mechanism; it is more important for the lower chlorinated congeners than for the higher chlorinated congeners. Vapor-phase PCBs accumulate on the leaves of plants; infect animals and humans directly or indirectly when feeding on it.
So, in the present study attempt to made detection of PCBs in places where old transformers were storage specially in greater Cairo and also is find suitable methods of treatment or partially removing of these compounds from soil contaminated with them at bench scale level in laboratory by using two methods for treatment and make comparison between them in efficiency of each method.
Twenty five samples of transformer oils were collected between August 2008 to November 2008 in three category areas in Greater Cairo (Bahteem- Nasr City- 6th October) and three soil samples were collected around the old transformers . The study count nearly 560 transformers were manufactured within the period from 1950 to 1986 .
Transformer oil samples were collected then extracted and treated with EPA Victoria method this method sets out a procedure for the determination of polychlorinated biphenyls (PCBs), as Aroclors®, in extracts from waste oil by GC using capillary columns with electron capture detectors (ECD). And soil samples were collected and treated and extracted with EPA method 3540c Soxhlet extraction for soil samples. And in this study synthetic soil samples were prepared in laboratory for make treatment of PCBs in them were samples were treated in laboratory by two methods, soil washing and solvent extraction method then after treatment by two methods the remaining solutions were analyzed by GC.
Aroclor® 1242, 1248, 1254 and 1260 (Supelco) were used to make quantification of the transformer and waste oil samples by peak matching method. The main instrumentation was a SHIMADZU GC-2010 equipped with electron capture detectors (ECD). A capillary column (DB-5, 50 m , 0.25 mm, film thickness 0.25 um) was installed. With an initial oven temperature of 150 °C, which was then raised to 300 °C at a rate of 3 °C/ min. And the column pressure was 234.4 (Kpa), the column flow was 1.06 ml/ min; the linear velocity was 28.0 cm/ sec under splitless condition. 8.0 µl of sample extract was injected into a GC, Samples were analyzed for PCBs using GC. The GC was connected to a computer to store and evaluate the output data.
Among 25 samples analyzed, PCBs were found in 9 samples. One of the analyzed samples showed 71 ppm, which is a higher concentration than the implementing criteria for treatment which is 50 ppm. Another sample showed 42 ppm, which is considered in need of field treatment before public use. Since test kits were unavailable during the field inventory survey, all of the transformers suspected to have insulating oil containing PCBs were not in-site checked, so it was possible that other transformers having PCBs contaminated oil at such high concentration level may exist.
Among 3 soil samples analyzed PCBs were found in 2 samples and by Comparing analytical results with several standards we found that these results is higher than the limit in WHO. where WHO have established a Provisional Tolerable Monthly Intake (PTMI) for Polychlorinated biphenyls (PCBs) of 70 picograms (10-12 g) per kilogram of body weight.
The PTMI is an estimate of the amount of chemical per month that can be ingested over a lifetime without appreciable health risk. Almost all exposure to PCBs and is through the food chain and the PTMI represents the cumulative exposure to PCBs from all sources including food and water. However, based on the results that PCBs were found, it is necessary to continue this kind of monitoring in other site to evaluate risks due to PCBs presence.
Then to make achieve treatment for these materials in soil in this study through selection of two methods for treatment soil washing treatment method and solvent extraction treatment method through bench scale experiment by making synthetic samples of soils in laboratory then make application of the previous two methods in these samples then make analysis for soils to make determination the concentration of PCBs in these samples after treatment with the previous two methods.
Soil washing method by using one of the types of traditional commercial detergents prepared in laboratory by using sulfonic acid and potassium hydroxide and then prepared serials of dilutions from the detergent in different percentages as follow: 1%, 5%, 10%, 15%, 20%, 25%, 50%, 100% and then used these serials to treat soil samples when the interaction between the contaminated soil and detergent within 30 minutes and we found that the efficiency of soil washing treatment method from 9.82% to41.76% according to percentage of detergent, where we found that the largest efficiency was 41.76% when we used 20% detergent.
And we used another method for treatment of soil was solvent extraction method by using different solvents with different concentrations as follow: 100% hexane, 25%:75% acetone: hexane, 50%: 50% acetone: hexane, 75%: 25% acetone: hexane, 100% acetone, and we used cheep solvents as kerosene and naphtha in 100%. We found that the efficiency of solvent extraction treatment method from 64% to 97.7% according to percentage and type of solvent used by the following order according to efficiency:
100%acetone> 75%acetone: 25%hexane>50%acetone: 50%hexane> 25% acetone: 75% hexane> 100%hexane > 100% naphtha> 100% kerosene.
So from the previous results from two methods for treatment of soil contaminated with PCBs we found that the solvent extraction method is more efficient than soil washing method in treatment of soil contaminated with PCBs. These data were needed to supplement existing information on the area to evaluate spatial distribution and range of PCBs concentrations in transformer oils which were collected from the transformer storage sites. Information on spatial distribution of PCBs in these areas will support development of a long-term compliance monitoring program for the PCBs in Egypt. This study showed the need for further studies concerning PCBs as a hazardous pollutant and how to find different methods for treatment and using alternatives for these compounds.
In this regard, we get to the final conclusions of the study that PCBs has been discovered in different areas of transformers storage , soil pollution may existed , treatment using organic solvents could be useful .
Therefore we recommend that the following:
1. Interest for listed all of these compounds across all regions which are using this type of oils by secure manner and stored specially in area where the contamination occurred for rehabilitation to be environmentally safe and healthy.
2. As the existing research in this area are very few, further studies and more attention to these dangerous pollutants should takes place and try to find different ways for treatment of these compounds according to local conditions or alternatives to use in accordance with the Convention Stockholm in 2002 on persistent organic pollutants.
3. Recommending the use of modern synthetic oils free from chlorinated compounds and others which causing environmental pollution.
And also we recommend bodies which used these compounds to:
1. Implementation survey of inventory of PCB used in transformers and capacitors.
2. Raising awareness about health and environmental risks of PCBs, procedures for the management, and cooperation with the media and non-governmental organizations.
3. Establishment of network information to EEAA and the concerned authorities in various sectors such as electricity companies for the management of hazardous chemicals by (storage, heavily trade, uses and disposal).
4. Establishment of a committee of experts to provide advice to the best technology to minimize the effects of potential sources of contamination of these compounds and the preparation of the road map for monitoring and treatment of materials contaminated with PCB.
5. The relevant ministries that have responsibilities for control of a large number of transformers and capacitors, such as Ministry of the Interior and Ministry of Defense, Ministry of Electricity for the application of inventory materials contaminated by polychlorinated phenyl polychlorinated and the Ministry of Health to implement the epidemiological surveillance.
6. We should work on collect this type of oils which harmful to the environment and make safe disposal of it to specialized agencies abroad because its presence stored were considered as not safe source for pollution.
We also recommended the study completed as follows:
• Find suitable practical and applied ways to extract these kinds of dangerous oils from contaminated soil that is on experimental level.
• Study of the method of disposal of these oils that have been separated by on of the practical ways (chemically or natural means) to protect the environment from pollution.
• Make comparative study for types of oils which are used to cooling electrical transformers to find the best from it or development the new varieties of these oils to used at the laboratory and experimental levels and know durability for extended periods of operation under difficult conditions of heat and voltage difference.