Water Quality & Pollution: Glossary of Terms
Water Quality & Pollution Glossary
Urban Wastewater
Urban wastewater refers to water carrying waste from urban areas, including households and the service sector. This water is often polluted with organic matter, pathogenic germs, bleach, and heavy metals from urban soil and vehicles.
Wastewater
Wastewater is any water that carries waste from human activities, making it contaminated with organic matter, detergents, heavy metals, and nitrates. It can be classified as urban sewage, industrial wastewater, or agricultural wastewater depending on the pollution source.
Water Quality
Water quality describes water’s suitability for its intended use (e.g., drinking, irrigation) and its ability to maintain ecosystems without causing harm. It’s defined by various characteristics (smell, taste) compared to its natural state or desired use.
Water Pollution
Water pollution occurs when chemicals, organisms, or energy forms are present in water at levels that make it harmful for human use (consumption, industrial processes) or ecosystems. Examples include pesticides and detergents.
Diffuse Pollution
Diffuse pollution originates from widespread sources rather than a single point. Pollutants are dispersed over large areas, making it harder to control than point-source pollution. An example is the emission of polluting gases from transportation.
Point Source Pollution
Point source pollution originates from a specific location, affecting a localized area. An example is a factory chimney emitting greenhouse gases. This type of pollution is easier to identify and address through technology, legislation, and control mechanisms compared to diffuse pollution.
BOD (Biochemical Oxygen Demand)
BOD is a chemical parameter indicating the amount of organic matter in water. It’s measured by determining the oxygen microorganisms need to oxidize the organic matter. BOD5, a common parameter, estimates BOD by incubating a water sample for 5 days at 30°C.
COD (Chemical Oxygen Demand)
COD is a chemical parameter indicating the amount of organic compounds in water. It’s measured by determining the oxygen needed to oxidize compounds using chemicals added to the water sample without the involvement of living organisms.
Eutrophication
Eutrophication is the nutrient enrichment of water bodies (rivers, lakes) leading to increased productivity in aquatic ecosystems. This enrichment is often caused by agricultural and urban contamination with nitrogen and phosphorus compounds (the main limiting factors in these ecosystems). Eutrophication alters ecosystems, impacts biodiversity, and affects water’s appearance and odor.
Sludge or Activated Sludge
Sludge or activated sludge is part of the biological processes in secondary wastewater treatment at wastewater treatment plants. It aims to remove organic matter from sewage by cultivating millions of aerobic decomposer microorganisms in an aerated and agitated tank. The resulting sludge is removed through sedimentation in secondary clarifiers.
Environmental Indicators
Environmental indicators are variables reflecting human impact on the environment. They can be pressure indicators (measuring human activity), state indicators (reflecting environmental impact), or response indicators (measuring human efforts related to the environment). An example is the amount of CO2 emissions.
Leaching
Leaching is the process where substances are carried away by water, typically rainwater or irrigation water, through contact with urban or industrial waste (landfills), fertilizers, agricultural pesticides, and livestock waste. This runoff often infiltrates the ground (continental waters).
Leachate
Leachate is the liquid resulting from leaching, the process of substances being carried away by water.
Oil Spills
Oil spills are a severe form of marine pollution, especially those from tanker wrecks. Oil forms a surface film and deposits a layer on the seabed or beaches, harming marine ecosystems, fisheries, and tourism.
Red Tides
: the excessive development (blooms) of certain species of marine plankton algae, harmful because they produce toxic substances that accumulate in filter feeders such as molluscs of commercial interest (oysters, mussels) that can then be toxic to humans. They are produced by eutrophication processes.
OD: chemical parameter measuring the quality of water whose presence is essential for the development of aquatic life. Increases in the clean waters, shallow water dynamics and decreases in organic matter, which it spent on its decomposition, deep and static.