unit 8

biological oxygen demand (BOD)

the amount of oxygen needed by microorganisms to decompose biological wastes into carbon dioxide, water, and minerals

composting

partially decomposing organic plant and animal matter to be used as a soil conditioner or fertilizer

dead zones

a location within a body of water that does not have enough dissolved oxygen to sustain life

dose responsive curve

plot of data showing the effects of various doses of a toxic agent on a group of test organisms

effluent

treated waste water, flowing from a lagoon, tank, treatment process, or treatment plant

endemic

term used to describe a species that is found in only one area; usually vulnerable to extinction

endocrine disruptors

man-made or naturally occurring chemicals that affect the hormones within an organism

dissolved oxygen

the amount of oxygen that is present in water

eutrophication

physical, chemical, and biological changes that take place after a lake, estuary, or slow-flowing stream receives inputs of plant nutrients (nitrates + phosphates) from natural erosion and runoff from the surrounding land basin

industrial solid waste

solid waster produced by mines, factories, refineries, food growers, and businesses that supply people with goods and services

methylmercury

any various toxic compounds of mercury containing the complex CH3Hg

municipal solid waste

solid materials discarded by homes and businesses in or near urban areas

non-point sources

broad and diffuse areas, rather than points, from which pollutants enter bodies of surface water or air (runoff from cropland, CAFOs, or parking lots)

oligotrophic

lake with a low supply of plant nutrients

oxygen sag curve

graphically represents the changes in dissolved oxygen levels in a body of water, typically a river or stream, following the addition of organic pollutants

pathogens

living organisms that can cause disease in other organisms (bacteria, virus, parasites)

persistent organic pollutants

a group of toxic chemicals that can remain in the environment for long periods of time and travel long distances through the air and water

point sources

single identifiable sources that discharge pollutants into the environment (smokestack, drainpipe, chimney, car)

primary sewage treatment

mechanical sewage treatment in which larger solids are filtered out by screens and suspended solids settle out as sludge in a sedimentation tank

range of tolerance

range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally

refuse

to refrain from buying or using a good or service in order to reduce one’s ecological impact and to save money

sanitary landfill

waste disposal site on land in which waste is spread in thin layers, compacted, and covered with a fresh layer of clay or plastic foam each day

secondary sewage treatment

second step in most waste treatment systems in which aerobic bacteria decompose as much as 90% of degradable, oxygen-demanding organic wastes in wastewater

septic tank

underground tank for treating wastewater from a home in rural and suburban areas. bacteria in the tank decompose organic wastes, and the sludge settles to the bottom of the tank. the effluent flows out of the tank into the ground through a field of drainpipes

tertiary sewage treatment

the final step in the sewage treatment process. involves the use of physical, chemical, or biological processes to remove remaining pollutants and pathogens from the wastewater (filtration, disinfection, nutrient removal)

thermal pollution

the increase in the temperature of a body of water, which can have a variety of negative effects on the ecosystem

toxic waste

form of hazardous waste that causes death or serious injury (burns, respiratory diseases, cancer, mutation)

waste management

managing wastes to reduce their environmental harm without seriously trying to reduce the amount of waste produced

waste to energy incineration

process of burning waste materials to reduce their volume and mass and sometimes to generate electricity or heat