Managing Hazardous Wastes Environmental Science 20

Types of Hazardous Waste Hazardous Substances and Hazardous Wastes Hazardous substances can cause harm to organisms and the environment, and they require special methods to reduce or eliminate their potential for harm. Many common products are hazardous such as: gasoline, pesticides, household cleaners and medicines. Hazardous Waste is a discarded substance that is or contains a flammable, corrosive, reactive and/or toxic substance.

Hazardous wastes are created at many points in the life cycle of a product, from research and development to final disposal.

Properties of Hazardous Materials

Hazardous Waste from Agriculture Pesticides are not just deadly to insects and other pests – they are also harmful to humans and other organism. Pesticides may be used up when applied to crops, but any leftover becomes waste material. Some pesticides breakdown quickly when they are applied and other do not. These are called persistent pesticides. One persistent pesticide is called DDT. DDT belongs to a class of hazardous materials called chlorinated hydrocarbons. DDT has been shown to accumulate in the tissues of humans and other organisms and has been linked to nervous system problems, seizures, premature births and reproductive problems. The use of DDT was banned in the 1980s. DDT is still used in some parts of the world to control diseases such as Malaria, which is dominantly spread by mosquitoes.

Hazardous Waste from Manufacturing and Industry The mining, oil and gas, chemical, and pulp and paper industries use and produce high volumes of hazardous substances. For example: cyanide is used in mining to separate metals from the ore. Heavy Metals may also be released, such as mercury, arsenic and lead. The situations is similar in the oil and gas industry. Exploring, drilling well, the refining process, and maintaining machines and vehicles are just a few of the activities that produce hazardous wastes.

Many common products produce hazardous wastes.

Hazardous Waste from Municipal Sources Municipal sources of hazardous wastes are closely linked to the use of consumer products, such as: batteries, antifreeze, paint, compact fluorescent light bulbs, and cleaners. One significant source is electronic products. Unwanted electronic products that enter the waste stream are called e-waste. Older electronics often contain polychlorinated Biphenyls (PCBs), which are heat resistant, fire resistant, and extremely harmful to organisms and the environment. Like DDT, PCB’s can accumulate in the tissues of organisms and cause harms in the nervous, immune, reproductive, respiratory and urinary systems. PCBs were banned in Canada in 1977, but they are still used in developing nations.

Effects of Hazardous Substances and Wastes on the Environment Hazardous materials can have a variety of effects on the environment. Factors that determine the nature and severity of the health effects include: Toxicity (how harmful) Duration of exposure (how long) Amount of exposure (how much) Route of exposure (inhaled, ingested, or absorbed) Over the past few decades, numerous accidents and some deliberate releases of hazardous substances into the environment have occurred. Your textbook explores some of these incidences.

Managing Hazardous Waste Environment Canada promotes a pollution prevention hierarchy. It emphasizes reducing the amount of hazardous waste produced according to the strategy outlined below: Reduce the amount of waste at its source Recycle wastes whenever possible Treat wastes to reduce their hazard or their volume As a last resort, dispose of wastes on land or incinerate them

Pollution Prevention Hierarchy

Treating Hazardous Wastes Treating hazardous waste involves converting it to a less hazardous substance and/or reducing its volume before disposal. There are a variety of technologies used to do this: Chemical – chemical conversion Physical – physical devices are used (filter) Biological – Use of biological organisms to remove contaminants (Bioremediation) Thermal – treating with extreme heat

Disposal of Hazardous Wastes Despite the best efforts of government, industries, communities and individuals, there will always be some wastes that need to be disposed of. There are 3 methods used in Canada: Deep Well Injection – Liquid hazardous wastes are injected into Deep wells below the Earth’s surface. The wells are cased with cement to prevent leakage, but leakage from older wells remains a concern. Non-Retrievable Storage – A special landfill for hazardous substances. This is the most common method and is monitored for leaks. Retrievable Storage – This is the most expensive option. Hazardous wastes are placed in containers in an accessible, but secure location, such as a building, cave, or abandoned mine. Waste can be monitored easily.

Questions Read sections 8.1-8.2 and answer the questions.