Anaerobic Digestion
Anaerobic digestion is a natural process that takes place in big bins where tiny bacteria break down plant or animal products, like food waste and animal manure, in a system without oxygen. Digesters are found near landfills, on farms, and at water treatment plants. They create a type of renewable energy called biogas, that can be used for heat, electricity, or fuel. Digesters also reduce odors and waste and produce digestate that can be used as a fertilizer or bedding for animals to rest on.
Old Landfill
The old Dumptown landfill is all covered over now. But because it was just a hole in the ground where residents and businesses threw away everything—including hazardous waste—it caused a big problem. Poisonous liquids seeped through the soil into the groundwater beneath the earth's surface and contaminated it. This underground plume of contamination started spreading toward even larger underground water supplies.
With some help from federal and state agencies, the new Recycle City government started cleaning up the problem. Using money from the businesses that had been most responsible for the contamination, a "pump-and-treat" system was built to remove the contaminated groundwater and clean it up. This system pumps water out of the ground, purifies it by filtering out all the pollutants, and sends it to nearby farms to water crops.
The system was very expensive to build and run, and it taught everyone a valuable lesson: It's much cheaper to prevent pollution in the first place than to clean it up later!
Unfortunately, there are many contaminated places in the United States. To help clean up these hazardous waste sites, Congress created Superfund. This is a law that lets the government find those who are responsible for creating the hazardous waste and make sure they clean it up. Superfund is also a name for the money the U.S. Environmental Protection Agency can use to clean up pollution from hazardous waste if they can't find who caused the contamination, or if those responsible don't have enough money to pay for the cleanup.