Mercury Decontamination of a Chloralkali Plant in Alexandria. Egypt
459
The review of available and feasible decontamination technologies revealed
that, regardless of which technology was chosen, the target value of 10 mg/kg Hg
in the treated materials can barely be reached. At the time of writing, no large
scale-treatment plants which could cope with the detected high mercury levels
were in operation or available at all. The treatment would cause very high costs,
and an additional landfill would be needed for the deposition of treated or
untreated materials with mercury concentrations above the target value. Based
on the findings, it was decided to refrain from the treatment of the wastes and,
instead - as there are no existing hazardous waste landfills in the country - to
utilize the available budget for the construction of a suitable state-of-the-art and
secure landfill for the long-term deposition of all solid wastes resulting from this
decontamination project. In this case "long-term" means at least 100 years, by
which time new technologies may be available to completely detoxify the residues.
An appropriate landfill site was selected in an uninhabited desert area
approximately 80 km southwest of Alexandria. The siting process, landfill
design, and the entire MCI decontamination strategy was reviewed and approved
by the Egyptian environmental and other involved authorities in Cairo.
4
Decontamination Concept
The overall strategy was to conduct the decontamination and demolition
activities in such a manner as to minimize the exposure of workers and the
environment to contaminated dust and mercury vapors. To accomplish this, the
use of manual labor for demolition was minimized, and a series of dust
suppression measures were implemented, such as the use of water sprays and
vacuums at points of potential dust emission.
A comprehensive work plan was prepared for all of the facility decontamination activities. A detailed inventory was made of all facility surface areas,
structures, and process units, with a description of the degree of contamination
and the recommended decontamination method for each item.
The decontamination concept for the MCI facility includes three general
phases of activity. Phase A involved facility cleanup, site preparation, and the
construction of treatment and storage facilities. Several facilities were constructed on site, including a cleaning pad for high-pressure washing of contaminated
items, a laboratory for analysis of solid and aqueous samples, a waste-water
treatment plant for demercurization of cleaning wastewater (from general site
cleanup and decontamination activities), a vehicle-wash for trucks and cars
leaving the site, and a personnel decontamination unit for the work crews. A
general cleanup of the entire plant was performed to remove debris, cleanup the
dust and dirt, and then pressure-clean the concrete surfaces, followed by the
initial pressure-cleaning of all mercury-contaminated process units and buildings. An interim storage facility was installed on site to store contaminated
materials until the off-site landfill was completed.
459
The review of available and feasible decontamination technologies revealed
that, regardless of which technology was chosen, the target value of 10 mg/kg Hg
in the treated materials can barely be reached. At the time of writing, no large
scale-treatment plants which could cope with the detected high mercury levels
were in operation or available at all. The treatment would cause very high costs,
and an additional landfill would be needed for the deposition of treated or
untreated materials with mercury concentrations above the target value. Based
on the findings, it was decided to refrain from the treatment of the wastes and,
instead - as there are no existing hazardous waste landfills in the country - to
utilize the available budget for the construction of a suitable state-of-the-art and
secure landfill for the long-term deposition of all solid wastes resulting from this
decontamination project. In this case "long-term" means at least 100 years, by
which time new technologies may be available to completely detoxify the residues.
An appropriate landfill site was selected in an uninhabited desert area
approximately 80 km southwest of Alexandria. The siting process, landfill
design, and the entire MCI decontamination strategy was reviewed and approved
by the Egyptian environmental and other involved authorities in Cairo.
4
Decontamination Concept
The overall strategy was to conduct the decontamination and demolition
activities in such a manner as to minimize the exposure of workers and the
environment to contaminated dust and mercury vapors. To accomplish this, the
use of manual labor for demolition was minimized, and a series of dust
suppression measures were implemented, such as the use of water sprays and
vacuums at points of potential dust emission.
A comprehensive work plan was prepared for all of the facility decontamination activities. A detailed inventory was made of all facility surface areas,
structures, and process units, with a description of the degree of contamination
and the recommended decontamination method for each item.
The decontamination concept for the MCI facility includes three general
phases of activity. Phase A involved facility cleanup, site preparation, and the
construction of treatment and storage facilities. Several facilities were constructed on site, including a cleaning pad for high-pressure washing of contaminated
items, a laboratory for analysis of solid and aqueous samples, a waste-water
treatment plant for demercurization of cleaning wastewater (from general site
cleanup and decontamination activities), a vehicle-wash for trucks and cars
leaving the site, and a personnel decontamination unit for the work crews. A
general cleanup of the entire plant was performed to remove debris, cleanup the
dust and dirt, and then pressure-clean the concrete surfaces, followed by the
initial pressure-cleaning of all mercury-contaminated process units and buildings. An interim storage facility was installed on site to store contaminated
materials until the off-site landfill was completed.