Landfills vs. Incinerators vs. ...
European countries are striving for waste management based on the 3Rs: Reduce. Reuse. Recycle. With this in mind, the European Commission considers landfilling a last resort, with incineration, incorporating energy recovery, being preferable. This is not a view that I share.
In my opinion, landfills* are less costly environmentally as well as economically. And they will remain so, as long as the overall environmental contamination from landfills is likely to be no greater than that from incinerators, whose ash, in any event, needs its own burial site.
Landfills are also preferable because they
• allow for resource recovery, something that incinerators--which operate most effectively with inflammable (but recyclable) paper and plastic--can't do
• involve greater job-creation potential, possibly less centralization, and less-challenging (more-accessible) technology.
But those who apply landfill-lining technology should not lull us into a false sense of security. Questions remain about the performance of synthetic liners. The author is aware of several instances where competent construction quality assurance (CQA) has detected holes in liners delivered from the manufacturer. CQA is also essential in verifying the quality of seam welding. Design specifications often call for the widest rolls possible in order to minimize resorting to this demanding, but vital, task. Even without problems with the new material and its deployment, damage during the construction process may compromise liner integrity.
Uncertainty also exists about the long-term durability and resistance of these synthetics. The reputed performance of high-density polyethylene (HDPE)--the commonest liner material, considered by many specialists as the best geomembrane for most purposes--varies widely. One study (University of Wisconsin, 1991) found that dilute solutions of solvents such as xylene, toluene, trichloroethylene, and methylene chloride penetrate HDPE in a matter of weeks. Another (by the Phillips Petroleum Company) warns about the embrittlement or penetration of HDPE by household items such as mothballs, margarine, and vinegar. <%=company%> says HDPE liners are guaranteed by manufacturers not to leak for 20 years. The Geosynthetic Institute estimates that HDPE should last hundreds of years.
Those who would authorize landfill should exercise due diligence, recognizing what landfills can and cannot do. Specific precautions would include prudent siting, scrupulous project design, and impartial review. The U.S. EPA's basic standard for a synthetic liner--such as HDPE, supplemented by a layer of low permeability soil or a geosynthetic clay liner--therefore should be considered a minimum landfill specification, particularly in wet areas. Construction, with quality assurance paid for by the entity liable for future contamination, must be followed by a professional operation that is independently monitored. Final capping must be effective and its integrity guaranteed by conscientious maintenance for as long as the fill's contents pose a risk.
For my part, landfilling's long-term risks call for a better solution. I recognize that many contaminants of concern, particularly in the U.S., are inorganic compounds that aren't deactivated through biologic treatment. In fact, the organic acids produced by biological activity can concentrate inorganics and increase their harmfulness.
Until we learn to reduce our waste considerably and to compost organic kitchen and garden wastes, bioreaction of MSW, using fermentation (with its biogas production), could be the least risky, most cost-effective solids-disposal method available.
* Standard landfills remove and treat the leachate or liquids produced by the decomposition of organic materials in rubbish. Bioreacting (so-called "wet") landfills recirculate these liquids to expedite decomposition and, incidentally, hasten biogas production. Before final bioreactor landfill closure, clean water is also injected into the facility in order to "rinse" the fill's contents. This is done to render the waste more inert and less likely to produce additional contaminated liquids, even if moisture manages to enter the buried material.
The author welcomes comments. Please contact: Tel: 351 82 442 345; e-mail: tlambe@undp.org