New solutions to contaminated land – less expensive and greener
By Randy Mott, director EAME, CHWMEG, and president of Phytoremedia sp. z o.o.
The EU is estimated to be spending over one trillion euro on the management of contaminated land this decade. Thousands of known sites appear to require some remediation; new sites are discovered every day. The most typical contaminated-land case arises during the sale or even the construction phase of a commercial project. The developer is on a schedule and accordingly looks for fast solutions. Due to time constraints, the ‘dig and dump’ option is the major course of action, costing a substantial amount per ton, involving many tons of soil and only moving the contamination to another site (where the developer now becomes a liable party for future problems).
Phytoremediation – using plants that extract the pollutants – is an emerging technology that has now been commercially demonstrated. Plants can either take up the contamination as bioaccumulation or break down the compounds and utilise part of the molecular mass in photosynthesis and transpire the rest out of their leaves. Plants can also ‘lock up’ some contaminants in their root systems to prevent their migration. Over 240 plant species have been successfully demonstrated to have at least one of these properties.
The key fact for developers and site owners is that this process is normally only 10 to 15% of the cost of the traditional approaches. The clean-up is dealing with 20-25 tons of plant matter per hectare instead of thousands of cubic metres of contaminated soil. Some plants can also have economic value as energy crops (willow) or building-material fibre (hemp). Other times, the plant will have to be treated as hazardous waste (as the soil is once it is removed). Besides the cost savings, this approach is favoured by environmental groups and does not involve the public disputes that often arise from an excavation and soil-removal plan.
The drawbacks or limitations on phytoremediation are principally the time it takes. Some contaminants can be removed in a two- or three-year cycle, while others, like heavy metals, are a much long-term project (although metals can be fixed in place). In the case of heavy metals, there are phytoremediation “crops” that have as much or more value than traditional food crops. There is no simple rule – every site is unique. Nevertheless, this means that site owners and developers need to plan in advance to avoid spending millions on soil clean-up in the middle of a construction schedule. Existing operating locations can also use phytoremediation to stabilize metals present to prevent their migration.
Some projects have already been approved in Poland under the Contaminated Land Law. Phytoremedia is working on two in Poland. Government approval of a phytoremediation project may itself add to the commercial value of property since it is a defined cost and not an open-ended liability. And thousands of sites match up with the characteristics of previously successful phytoremediation projects abroad. Most common organic contamination can be addressed with this technology. This includes pollution from PAHs, including naphthalene and benzo-a-pyrene; PHCs, including pentane and hexadecane; BTEXs, including benzene and toluene; explosives, including TNT, RDX and most others; BTME, TCE and other volatile organic compounds. Heavy-metal contamination prevalent at many locations in Poland requires a longer-term remediation plant, which may still be feasible, especially if a commercially valuable plant is utilised. For large areas of contamination from diffuse sources, such as air pollution, phytoremediation may be the only feasible option.
Phytoremediation is an excellent option, where feasible, for idle industrial land and commercially active sites with portions of unused contaminated land. It is available in Poland and supported by a team of international experts. Hopefully this less onerous remediation measure can expedite the clean-up of thousands of sites which might otherwise linger idle or in litigation and complex transactions for years or even decades.