Solutions for the Future

 Collection, Removal, Capping

One of the most basic solutions available is the collection and removal of the contaminated materials.  This is relatively simple but may still require the use of equipment that is not available or affordable locally, such as earthmoving equipment.  In any such project, the final disposal of the contaminated material is always a concern but in many cases an acceptable solution can be found.

In other cases, covering or “capping” of contaminated material may be a good option.  For example, in abandoned mining areas, the materials contained by the “tailings dams” (fine waste material form processing) may be left to dry out, and then they are often picked up in windy conditions to form clouds of toxic dust.   Covering these areas with soil and vegetation or other material can essentially eliminate the problems.

Bioremediation (eg: cow dung and molasses)

The use of additives to encourage the growth of microbes to speed bio-degradation is a well-established technology.  The challenge often is the cost of specific engineered additives and the solution is frequently the use of local substitutes, which may be considerably less effective than their high tech counterparts but can be a very small fraction of the cost.  Diluted cow dung has been used very effectively in some cases.  Molasses or other sugar byproducts can be used as a cheap substitute for electron donor compounds, in certain applications.

Bioaccumulation (eg: plants and worms)

Bioaccumulation of heavy metals is a well-known phenomenon.  It is perhaps best known in the context of fish, where mercury in tuna is the classic concern. This concentration of certain heavy metals occurs in plants as well. Using plants that have particularly high absorption of the metals can gradually remove the contamination from the soil.  Solutions are typically quite location specific and so local knowledge (through agricultural and other institutes) is critical and field trials are essential.

Another, somewhat unusual application of bioaccumulation is the use of vermiculture (worms) to deal with sites contaminated with organics and metals.  One successful project in India combined the removal (to a secure landfill) of a large quantity of dumped hazardous waste with a vermiculture treatment of the moderately contaminated surface that was left.  The application, over several seasons, of a simple microbial accelerator together with introduction of a large community of specially bred earthworms, resulted in major improvement in soil condition and fertility, together with large reductions in remaining heavy metal concentrations when the worms were harvested and removed.

Wetland Systems

Natural wetlands purify wastes (especially domestic waste) through a number of mechanisms.  Various forms of artificial wetlands have been developed and can be very effective, especially for smaller flows.  An innovation which is now emerging and has significant potential is the use of designed wetlands to improve the quality of wastewater streams containing high levels of metals.  These systems function by a mixture of biochemical mechanisms, which alter the solubility of metals and physical (filtering) mechanisms that trap and hold the particles.  The capacity and lifetime of such systems is finite but they may be a cost effective way for dealing with run-off from polluted sites while efforts are underway to remove the sources. Monsoon seasons pose a particular challenge for wetlands and other bioremediation approaches in many tropical countries.  Intense seasonal rains can cause havoc with systems designed for relatively stable conditions.

Superfund-Type Solution

Despite being criticized for the high legal costs associated with its early days, the U.S. Superfund system provides a practical approach to these challenges.  The government can proceed to deal with the most urgent and hazardous sites, using the resources provided in the Fund, while working to identify the responsible parties and using legal proceedings and public pressure to recover the costs from them. In 2008, for example, Superfund secured commitments of close to 2 billion USD from private companies to reimburse the government and to provide funds for dealing with specific identified sites.

In 2008, Blacksmith began efforts to create the global Health and Pollution Fund to finance the cleanup and elimination of legacy pollution in the developing world.