PCBs TREATMENT FACILITIES
Uses of Polychlorinated Biphenyls (PCBs)
Concern of Characteristics
PCBs shall be Phased Out
Why PPLI PCBs Treatment Facility?
PCBs Waste Treatment Plan
Dismantling and Segregation
Picture 1. Activated Carbon Filter Unit for filtering the air Picture
Picture 2. Autoclave Unit for Decontamination
Decontamination process is a process of residue removal (PCBs oil) on transformers including its component by using solvent vapor. This process is carried out in an autoclave unit under vacuum condition and closed system. Solvent that is used in decontamination process are PerChloroEthylene (PCE) or TriChloroEthylene (TCE).
Solvent will be heated until its vapor phase and rinse the contaminant in material continuously. The solvent vapor thencondensed using cooling system and recycled in distiller (under vacuum condition) and evaporated again, and decontamination process repeated. This cycle will continue until the expected PCBs concentration has been reached. So that the solvent will be re-used and still running in the system.
If the decontamination target has been reached, the transformer/ material has already been decontaminated. Material is removed from the autoclave and “dried” in the drying area which is equipped with an activated carbon filter to ensure that no solvent vapor is released into the environment. The decontamination process workspace is also equipped with an activated carbon filter as a form of anticipation if there is solvent vapor released into the work environment.
Metal material from decontamination process can be recycled, and other material that can not be recycled will be processed and disposed in the landfill.
Dechlorination and Oil Purification
Sodium metal will be dissolved in PCBs oil (in small quantity) in reagent tank as a preparation step before being put into dechlorination tank.
Reagent tank and dechlorination tank will be heated using diathermic oil boiler and maintained its temperature at 110 C. After that, sodium mixture will be pumped into dechlorination tank which containings PCBs oil and the reaction proceed. Dechlorination process is conducted in batch system.
The dechlorination reaction process takes approximately 30-60 minutes and periodically sampling is carried out to determine the concentration of PCBs in the dechlorination tank. When the process is complete (the PCBs concentration has reached the set target), the oil is ready to be filtered. Bleaching earth is added before the oil enters the filtering unit. Oil free PCBs from the dechlorination tank, after the temperature is lowered then filtered using a filter press. The filtered oil free PCBs will be further processed in the oil purification unit. The filtered cake or sludge is processed by Stabilization before being stockpiled in landfills.
Oil free PCBs from the dechlorination process after the filtering process are pumped into the purification unit to reduce the water content to 10-15 ppm and remove dissolved gases. After this series of processes is completed, the oil free PCBs have been purified and ready to be used again in
the transformer and have met the transformer oil standard/ specification.
Safety and Environmental Monitoring
Measures for Air Contamination
- Exhaust from vacuum pumps are pre-treated
by activated carbon as a safety net before
- Exhaust from dismantling area is pre-treated
by activated carbon before released.
- Negative pressure operations
Measures to Prevent Leakage
- Spill containment (drainage and sump pit)
- 1% slope of the building floor
- Floors are coated with epoxy.
- Automatic fire alarms
- Chemical fire extinguishers
- Fire hydrants
Regular monitoring for PCBs:
- Perchloroethylene in ambient air
- PCBs in surface water
Quality control is conducted by a qualified
analytical laboratory as certified by :
- ISO/ IEC-17025
- MOEF Approved Environmental Laboratory