Development of system for extraction of polychlorinated biphenyl (PCB) from in-service transformers

The United Nations Office at Nairobi (UNON), on behalf of the United Nations Environment Programme UNEP invites qualified interested firms to submit Expression of Interest (EOI) to participate in the upcoming solicitation for provision of a system for the extraction of polychlorinated biphenyl congeners (PCBs) from contaminated dielectric mineral oil used in in-service transformers. 1.BACKGROUND Owing to their environmental persistence and human and ecological toxicity, PCBs were one of initial 12 Persistent Organic Pollutants (POPs) listed in the 2001 Stockholm Convention. Annex A of the Convention requires that Parties eliminate the use of PCBs by 2025 and destroy them with a method consistent with Environmentally Sound Management by 2028. In the case of retro-filled transformers The Convention specifies that residual concentrations cannot exceed 50 ppm. The ideal scenario would involve a technology allowing for the extraction of PCBs from in-service transformers without requiring their being taken out of service The scope is divided into two distinct phases. Phase I is a bench scale proof of concept. The proposed technology should effectively reduce PCB concentrations in mineral oil (commonly present at concentrations of below 2000 ppm) to < 50 ppm (the Stockholm Convention threshold for POPs waste). The test should be carried out in environmental conditions reflective of those present in the field. The system should be amenable to transformers of different sizes and configurations. The resulting concentrated PCB should be potentially liberated from the adsorbent material used for extraction from the bulk oil in the unit and available for disposal, thus regenerating the adsorbent substrate for potential re-use. Following approval of Phase I results by UNEP, the qualified vendor will proceed to Phase II. Phase II will involve the field deployment of the technology on an energized transformer at the location of the vendor’s choosing. 2. ASSIGNMENT OBJECTIVE The project requires the development of a system for the collection of PCBs from oil from in-service transformers. It is envisaged that the project will be executed over a period 6 months to allow for follow-up sampling and analysis to confirm initial results. 3. SERVICES TO BE PROVIDED Phase 1 services The first phase of the project will involve the development and bench scale testing of a system for extraction of polychlorinated biphenyls from in-service transformers. One incarnation could involve the use of materials which capitalise on the specific physical and chemical characteristics of the PCB molecules relative to the bulk mineral oil dielectric fluid (density, polar charge, size etc). The idea would be to “capture” the PCB on a suitable substrate which is stable under the operating conditions and which does not impede the operation of the transformer unit. The substrate could be arranged in a packed column arrangement preferentially adsorbing PCBs while allowing free flow of non-PCB transformer oil back into the transformer unit. The column could then be removed after a given period and recharged, either returning to use in the same unit until Convention targets (i.e. < 50 ppm) are met or installed for use on a different transformer. The column could be colourmetric providing an indication of column saturation and breakthrough. Whilst this would be seen as the ideal scenario for operation bidders are asked to provide proposals with alternative technologies as applicable. The proposed technology should effectively reduce PCB concentrations in mineral oil in the range of 2,000 ppm to < 50 ppm. The test should be carried out in environmental conditions reflective of those present in the field. The system should be amenable to transformers of different sizes and configurations. The loaded column should be re-usable with potential to remove the concentrated PCB held on the solid substrate. Phase 2 services Phase II activities will be carried out following approval of Phase I by UNEP. Phase II will involve the field deployment of the technology on an energized transformer at the location of the vendor’s choosing. The transformer should contain PCB oil of at a maximum concentration of 2,000 ppm and be under load for a minimum of 30 days prior to field testing. Following field testing, sampling and analysis of transformer oil should be carried out at maximum intervals of 30 days for at least 90 days from testing. The capacity and overall performance of the transformer should not be adversely affected following the extraction and replacement of PCB oils. Given the severity of the occupational and environmental hazards associated with working on PCB transformers under load, the selected contractor is expected to provide a detailed health and safety plan consistent with international best practice (e.g. US OSHA, EC or similar). The complete details of the requirement will be provided in the tender documents that will be issued to bidders after this request for EOI is closed.