Waste Management: Page 8 of 14

Smart waste disposal

Waste disposal sits at the bottom of the waste management hierarchy as the least preferred option. Yet for many developing countries, which now practice open dumping of trash, trucking waste to managed landfills represents a cost-effective step in advanced waste management.

In this section, we look at smart waste disposal alternatives.

Sanitary landfills

Today’s sanitary landfills are engineered sites where waste is managed to prevent environmental contamination. These landfills isolate waste from the environment while it degrades biologically, chemically and physically.

A primary technology challenge at landfills is managing the release of methane-rich landfill gas caused by the natural breakdown of organic material. These gases can make a significant contribution to GHG emissions.

Smart waste disposal solutions start with removal and conversion of organics from the waste stream before they get to the landfill. In addition, waste managers can implement systems to collect and use the landfill-generated gas for heat or electricity production. Methane captured at San Diego’s Miramar Landfill provides 90% of the fuel to power electrical generators at the local Metropolitan Biosolids Center and North City Water Reclamation Plant.

Bioreactor landfills

Unlike a traditional sanitary landfill, a bioreactor landfill accelerates the decomposition of organic waste by intentionally adding liquid and air to enhance microbial processes. Where decomposition in a dry landfill can take

30 to 50 years, the process takes only 5 to 10 years at a bioreactor landfill. By stepping up the rate of decomposition, the volume of material in the landfill rapidly shrinks and creates space for more material. As a result, fewer new landfills are needed.

Managing the biological, chemical and physical processes occurring in a bioreactor landfill requires the use of remote monitoring networks, sensors and other sophisticated technologies.

While not yet widely adopted, bioreactor landfills are gaining attention due to the potential they have to extract landfill gases and convert them to fuels. The bioreactor landfill near Ashville, North Carolina recently added a gas-to-energy operation. It’s now producing enough fuel to run a generator that powers 1,110 homes a year.

Solar-capped landfills

When a landfill closes, the site is typically sealed with a polyethylene cap and then covered with several feet of compacted soil on which grass is planted.

One alternative capping system is to cover the buried garbage not with dirt and grass, but with solar panels. This not only eliminates the need to mow grass and replace eroding soil, but brings underutilized acreage into renewable energy production.

Landfill solar farms are already in place in several states, including the Hickory Ridge landfill near Atlanta, Georgia with 7,000 panels installed. The EPA and the U.S.Department of Energy are offering guidance to landfill operators and solar energy developers looking to integrate solar projects with retired landfills.