waste management

Waste Management

The challenge of waste disposal has becoming increasingly difficult since the industrial revolution. With increasing population, urbanization, and prosperity, modern society engages in mass production and mass consumption. As a result there is considerable waste generated which has far reaching affects. Many nations are examining options to lessen the amount of waste generated, and how to manage that waste.

Per capita the world’s largest consumer, the United States produces a quarter of the world’s waste.  The waste that people dispose of in their garbage is referred to as Municipal Solid Waste.  This is primarily household waste that is sometimes called urban solid waste.  There are other types of waste including medical, air-borne, liquid, or even hazardous waste from nuclear power plants.

Hazardous and Non-Hazardous Waste
All municipal solid waste (MSW) and industrial waste constitutes non-hazardous waste.

The U.S. Environmental Protection Agency, which collects data on waste generation and disposal, reported the United States generated over 250 million tons of waste in 2010. That averages out to about 4.43 pounds (2kg) per person/per day. Around 85 million tons of this was recycled and composted. These figures do not include construction, hazardous, or industrial waste.

Hazardous waste includes radioactive, chemical, and dangerous biological materials. Anything that is flammable, toxic, radioactive, reactive, corrosive, carcinogenic, infectious or poisonous presents potential risk to humans and the environment. Hazardous substances can be found in many everyday items including batteries, pesticides, thermostats, and lamps.

The volume of medical waste is also on the rise and includes all waste generated from the diagnosis or treatment of human beings and animals. This includes waste from immunization, laboratories, and research. A more gruesome form is pathological waste. Autoclave and microwave solutions are usually employed to deal with medical waste.

Methods of Waste Management

Open Burning
Open burning of waste, while once widely practiced, is strongly discouraged today. It releases poisonous gases and toxins (e.g. dioxin) directly into the environment which are harmful to humans and animals.

Composting is used as a means of managing organic household waste, E.g. branches and leaves. This benefits the environment as it reduces the formation of gases in landfills and helps replenish the soil. Over the past few years, many U.S. cities like Portland, Seattle, and San Francisco have added composting to their waste management solutions, and have started offering curbside pickup.

A furnace is used to burn the waste in the presence of oxygen, leading to ash, flue and gas. The remains are then buried inside the earth in landfills. Research has shown the gases produced during the process of incineration are extremely toxic and much more dangerous than the original waste material. Due to public opposition to this method of waste management, no new incinerators have been built after 1997. Pyrolysis is similar to incineration, but the solid waste is burned without oxygen.

This technology involves using oxygen to convert waste containing carbon into gases (syngas), both combustible and non-combustible. The resulting gas is used to produce heat energy and leftover waste ends up in landfills.  Landfill space is reduced and usable energy is produced from the waste. Out of 140 plants worldwide, 19 gasification plants are located in the United States.

Landfills are areas where large amounts of waste is accumulated and eventually buried.  There are even parks built on top of landfills. However, without proper management landfills can have a harmful effect on the environment.  When the solid waste inside the landfill degrades, it releases gases including methane and carbon dioxide. These gases penetrate through the soil and pollute the surrounding air. Landfills that are not properly sealed and capped are also a risk. Rain water can seep into the solid waste, leading to the formation of leachate, a toxic liquid.  Water contamination occurs when leachate leaks into natural groundwater streams.

Due to the dangers associated with landfills; the U.S. government has closed several hundred landfill sites, and enacted strict regulations. Many landfills being built today are designed to trap energy released during the process of decomposition and use this for power generation. Bioreactor landfills help speed up the decomposition process.

Recycling Helps
Although challenging, even most hazardous waste can be recycled safely and effectively which has obvious benefits to the environment.  In addition to reducing GHG (Greenhouse Gas) emissions, it can also reduce air and water pollution by keeping harmful materials out of landfills.

Another major form of waste that is causing issues is e-waste.  To learn more check out the page on e-waste.