Controlling PCB emissions to the atmosphere

Recycling is all about efficient use and reuse of valuable and sometimes scarce material resources allied to care for the environment in the process. In the five year history of the World Demolition Awards, the judging panel has usually opted to select a specific project as the winner of the Recycling & Environmental category.

In 2013, the mould was broken, with the award going to Danish contractor J Jenson A/S, who has developed a system in conjunction with surface cleaning specialist Omø A/S that allows the clean, controlled and contained removal of hazardous coatings, such as paint containing Poly-Chlorinated Biphenyls (PCBs) and lead

Poly-Chlorinated Biphenyls are named as being among the world’s 12 most dangerous pollutants. PCBs were widely used by the construction industry in Denmark from 1950 to 1977, at which time their use was banned. Today, PCBs, along with lead, pose a major challenge when buildings dating from those years are being internally remodelled or totally demolished. Using traditional removal methods these substances can easily spread as dust in the atmosphere both inside and outside the building, and inhalation of these substances can be extremely hazardous to health, including the potential to cause brain damage.

Traditional techniques for removing such coatings frequently involves the use of blasting the surface to be cleaned with abrasive particles, which can create dust, noise and waste materials that have to be contained in some manner.

This offers the potential for the escape of potentially hazardous materials into the environment and a working environment that is far from ideal. In addition, methods for separating the toxic substances from the blasting media were not readily available.

J Jensen identified a solution from the USA called SpongeJet, where blasting was carried out using tiny sponge mushrooms, instead of sand, that absorb the particles of the coating being removed, thus minimising dust and other debris production. Subsequently J Jensen, working together with a French company, developed a very effective carbon filter that efficiently removes the PCBs and lead absorbed by the sponge mushrooms. This system was then built into a container, which means that nothing escapes. The uniqueness of the J. Jensen and Omø closed system is that all dust and other hazardous vapours are directed into the container through the use of an Omø vacuum cleaning system. The PCB and lead removed by the filter from the sponge mushrooms can be packed into sealed and lined barrels directly from the container and the small sponge blasting media cleaned and reused. This means the solution also works on environmental clean-up and demolition will be significantly less risky for employees of J Jensen and Omø.

The system consists of three main elements. A Sponge-Jet feed unit provides a constant flow of the sponge mushrooms, which are available in different hardnesses and surfaces depending on the nature of the coating to be removed, to improve productivity and also controls the media mix and the pressure. The Sponge-Jet media classifier cleans and separates used blowing agent into three categories – oversize waste, small waste particles, dust and broken sponge, and recycled abrasive sponge. A control unit monitors the system to ensure efficient operation and automatically shuts the Sponge-Jet system down in the event of malfunction to prevent the potential release of hazardous substances into the atmosphere.

The two companies believe that the solution has international potential. A significant number of public and private buildings not only in Denmark but across Europe are contaminated with PCBs and lead. This suggests that there are great opportunities for this Danish invention. J. Jensen A/S and Omø A/S are already in discussions with potential partners around the world concerning the use of this system.