The Past 20 Years have Witnessed Tremendous technological advancements in the field of solid waste management. Many of these advancements have become part of standard industry practices in the United States, but have not yet been realized in developing nations. As we continue to develop new technologies and strengthen existing ones, how will the rapidly developing field of nanotechnology impact the waste industry during the next 20 years and beyond?
Nanotechnology is a broad, general term used to refer to materials and processes involving nanoparticles, which most often measure between 1 and 100 nanometers (nm) in any single dimension. A nanometer is equal to 1 × 10-9 meter, and these nanoparticles and nanomaterials have great potential for use in medical imaging, drug delivery, fuel cells, manufacturing, quantum computers and environmental remediation, among a multitude of other activities.
The nanostructured materials being researched, developed and produced by academic institutions and businesses in the United States during this decade and the next will likely be incorporated into the methodology and protocols utilized to collect, process, dispose and monitor wastes generated within our communities. Among the possibilities:
Iron oxide nanoproducts include magnetic and non-magnetic crystals. The magnetic crystals could be incorporated into plastic drink bottles and other consumer packaging to enable separation of co-mingled recyclables using magnets, similar to steel cans.
The lightweight plastic grocery bags that are so difficult to keep in the working face at solid waste disposal facilities during windy days could be produced with iron oxide nanomaterials to better capture these plastic grocery bags using electro-magnets located adjacent to the working face (similar to litter fences).
Using iron oxide to treat landfill gas containing elevated levels of hydrogen sulfide (i.e. the iron sponge) is not a new idea. However, the availability of nanoproducts and their incredibly large surface area (about 320 square meters covered by 1 gram), which is a valuable characteristic of such materials, allows for new methods of application for landfill gas treatment, such as down-well or in-waste rather than the traditional filter media.
Similar to how geosynthetic clay liners incorporate a low permeability clay product sandwiched between two geotextiles sewn together, carbon nanotubes, called “fulerenes,” could be attached to the geosynthetic layers of a landfill bottom liner system to provide pre-treatment of leachate collected at the bottom of the landfill.
In anaerobic environments, the potential for elevated ammonia concentrations to build up in the leachate may require bioreactor landfills to treat leachate to be recirculated. Rather than operating a nitrification pretreatment plant, nanomaterials may be able to provide a forum for chemoautotrophic bacteria to yield high nitrate-containing leachate for distribution into the wastes. These same nanoproducts may provide extensive surface areas to support the facultative heterotrophic bacteria within the wastes to perform denitrification.
Incorporating the use of nanomaterials as alternate daily covers at landfills may prove difficult because of challenges with application onto the working face; however, the ability for such nanoproducts to enhance the distribution of beneficial microbial populations in order to accelerate landfill waste stability and enhance the biochemical methane potential will likely encourage the waste industry to pursue such activities.
The list of ideas and possibilities for incorporating nanomaterials into the everyday practices within the solid waste industry could go on and on. Applications and processes that seem infeasible today may very well be common industry standards within the next 20 years. What are some of your ideas for technological advancements related to solid waste management that may be practical now that nanoparticles are more readily available?
Robert Dick is a vice president at NSWMA member company SCS Engineers in Virginia. E-mail him at [email protected].