By Michel Buron (MSc), June 2006
The STOCKHOLM CONVENTION is a global treaty to protect human health and the environment from persistent organic pollutants (POPs). POPs are chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of living organisms and are toxic to humans and wildlife.
POPs circulate globally and can cause damage wherever they travel. In implementing the Convention, Governments will take measures to eliminate or reduce the release of POPs into the environment.
Governments within the EC have the policy of only permitting imports of hazardous wastes for disposal where the exporting countries do not have and/or cannot reasonably acquire the ability to dispose of the wastes concerned in an environmentally sound manner.
Similarly, developed countries in Asia do not encourage export of waste to countries under development, principle in line with the Basel Convention.
Nowadays the most frequent requests for shipments of hazardous wastes for disposal are: Poly-Chlorinated Biphenyl (PCB), Persistent Organic Pollutants (POPs) such as Hexachlorobenzene (HCB), DDT, chlordane, toxaphene, dieldrin, aldrin, endrin, hepachlor, mirex, dioxins, furans and other harmful pesticide substances.
Indeed Asian nations do not have the capabilities to treat such acute hazardous wastes and seek treatment overseas. However the enforcement of the Stockholm Convention since May 2004 prohibits such activities.
Persistent Organic Pollutants (POPs) are chemical substances which are extremely stable, and are known to accumulate in biological tissue thereby posing a risk of adverse effects to human health and the environment and pose a risk to the global environment. Polychlorinated biphenyls (PCBs) are a class of chlorinated hydrocarbons that have been used extensively since 1930 for a variety of industrial uses. They consist of two benzene rings joined by a carbon-carbon bond, with chlorine atoms substituted on any or all of the remaining 10 carbon atoms. PCBs include mobile oily liquids and hard transparent resins, depending on the degree of substitution. Their valuable characteristics derives from their chemical inertness, resistance to heat, non-flammability, low vapor pressure and high dielectric constant and where intensively used as coolants in transformers and dielectrics in capacitors.
PCTs were used in almost exactly the same applications as PCBs but in smaller amounts. As well PBBs was used as a fire retardant in plastics, coatings, lacquers and polyurethane foam (Source 1).
Prohibition on future use
The Stockholm Convention (www.pops.int) prohibits the production and use of PCBs except in equipment already in use and has set a deadline of 2025 for the elimination of this remaining use of PCBs. The Convention came into force on 17th May 2004 and is legally binding for all its Parties.
The quantities of POPs are difficult to estimate as almost no inventory exists on a national level. It is estimated to more than one million tons of PCBs and 100,000 tons of obsolete pesticides in countries that are not member of the OECD.
PCB destruction facilities are mainly located in Europe and USA. Where suitable facilities are unavailable, trans-boundary transport of PCB wastes may represent the Best Practical Environmental Option.
Waste management priorities
High-concentration liquid PCBs, PCTs and PBBs. represent the highest risk. Countries should therefore focus on the management and elimination of such as waste as a first priority.
- Very high concentration: >10% or 100,000 mg/L PCBs wastes
- Medium and high concentration: 500 ppm - 10% PCB wastes
- Low concentration: 50 - 500 ppm PCB) wastes
Destruction and disposal criteria
The Basel Convention has adopted 50 ppm (50 mg/kg solids, 50 mg/L liquids) as the concentration limit above which PCBs are considered hazardous.
The Basel Convention recommends that all processes that destroy PCBs, PCTs and PBBs have a 99.9999% DRE and reduce PCB, PBB and PCT levels to below a scientifically-based criterion.
Inventory of World-Wide PCB destruction capacity: the UNEP report
We recommend the lecture of the "The Environment Programme of the United Nations (UNEP) released in 1998 a first issue of an inventory of world-wide PCB destruction capacity". It reviews the PCB problematic, destruction techniques, storage & transport and lists the treatment facilities that treats, or are capable of treating, a wide range of chlorinated organic substances, and other wastes.
In South-East Asia, they are currently no dedicated treatment facilities able to dispose properly of POPs. It has been reported that small quantities are destroyed in cement kilns and existing hazardous waste incinerators.
UNEP recognized the Persistent Organic Pollutant as an imminent danger for human health and nature and that trans-shipment of POPs may represent the best practical environmental option. UNEP recognizes that high temperature incinerators, incineration in cement kilns and chemical treatment are proven destruction technologies. The Stockholm Convention recently enforced (on 17/05/2004) has set a deadline of 2025 for the complete destruction of PCBs presently in use. Because they are currently no treatment centre in South-East Asia, POPs are exported mainly to Europe.
The lack of treatment facilities in South-East Asia results in an opportunity to develop such activities e.g. retrofitting an existing facility as a base to develop a POPs centralized treatment plant in the region.
1) The Environment Programme of the United Nations (UNEP) released in 1998 a first issue of an inventory of world-wide PCB destruction capacity
2) Technical guidelines on wastes comprising or containing PCBs, PCTs and PBBs (UNEP)
3) Destruction Technologies for polychlorinated biphenyls (PCBs) M.S.N Mujeebur Rahuman, Luigi Pistone. Ferruccio Trifiro and Stanislav Miertus. European Community (1991).
4) Basel Convention: PCB, PCT and PBB technical guidelines, 3rd draft, prepared by Environment Canada Toxics Pollution Prevention Directorate, March 2003.
5) PCB in electrical Devices: management, treatment and disposal by Johanne Hanko (BizAsia Network), June 1999.
6) Hazardous waste market survey in the Eastern Seaboard of Thailand, Michel Buron (BizAsia Network), March 2003.
7) Directive for the Laws of the Member States on the Controlled Disposal of PCBs and Equipment or Objects Contaminated by PCBs in Order to Dispose of Them Completely, Brussels, Belgium, 11 pages.
8) United Nations Environment Program (1989). Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal, Final Act, Geneva, Switzerland, 91 pages.