Short answers, pulled from the story.
Waste is any unwanted or unusable material, defined as any substance discarded after its primary use or that is worthless, defective, and of no use. The Basel Convention defines it as substances disposed of, intended to be disposed of, or required to be disposed of by national law, while the European Union calls it an object the holder discards, intends to discard, or is required to discard.
The main types of waste include municipal solid waste, household and commercial waste, construction and demolition debris, hazardous waste, radioactive waste, electronic waste, mixed waste, medical waste, and metabolic waste. The United States defines five types of radioactive waste, including high-level waste, transuranic waste, uranium or thorium mill tailings, low-level waste, and TENORM.
The Environmental Protection Agency concluded that 292.4 million U.S. short tons of municipal waste was generated in 2018, equal to about 4.9 pounds per person per day. Of that total, approximately 69 million tons were recycled and 25 million tons were composted.
Electronic waste, often called E-Waste or E-Scrap, includes discarded televisions, computers, cell phones, printers, scanners, and fax machines that contain recoverable metals like iron, gold, palladium, platinum, and copper. The EPA estimated 2.37 million tons of these devices were discarded by United States consumers in 2009, of which only 25 percent were recycled.
Waste management is an environmental justice issue because its burdens fall disproportionately on marginalized groups, including racial minorities, women, and residents of developing nations. The charity Tearfund estimates that between 400,000 and 1 million people die each year in developing countries from diseases caused by mismanaged waste.
Energy recovery from waste, called waste-to-energy, extracts heat, electricity, or fuel from non-recyclable materials through processes including combustion, gasification, pyrolysis, and anaerobic digestion. Plasma arc heating raises municipal solid waste to temperatures between 3,000 and 10,000 degrees Celsius, releasing energy through an electrical discharge in an inert atmosphere.