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Bacterial water contamination The introduction of unwanted bacteria into a water body. Base An alkaline substance that has a pH that exceeds 7,5. Bed Load Sediment particles resting on or near the channel bottom that are pushed or rolled along by the flow of water. Benthic zone The lower region of a body of water including the bottom. Bicarbonates Salts containing the anion HCO3-. When acid is added, this ion breaks into H2O and CO2, and acts as a buffer. Binder Chemicals that hold short fibres together in a cartridge filter. Bioaccumulantion The increase in concentration of a substance in living organisms, as they take in contaminated air, water, or food, due to slow metabolization and excretion. Biochemical Oxygen Demand (BOD) The amount of oxygen (measured in mg/L) that is required for the decomposition of organic matter by single-cell organisms, under test conditions. It is used to measure the amount of organic pollution in wastewater. More info on BOD and waste water treatment Biocide A chemical that is toxic to microrganisms. Biocides are often used to eliminate bacteria and other single-cell organisms from water. Biodegradable pollutants Pollutants that are capable of decomposing under natural conditions. Biofilm Population of various microrganisms, trapped in a layer of slime and excretion products, attached to a surface. Biological contaminants Living organisms such as viruses, bacteria, fungi, and mammal and bird antigens that can cause harmful health effects to humans. Biologically activated carbon Activated carbon that supports active microbial growth, in order to aid in the degradation of organics that have been absorbed on its surface and in its pores. Biological oxidation Decomposition of complex organic materials by microrganisms through oxidation. Biomonitoring The use of living organisms to test the suitability of effluents for discharge into receiving waters and to test the quality of such waters downstream from the discharge. Bioremediation The biological treatment of wastewater and sludge, by inducing the breakdown of organics and hydrocarbons to carbon dioxide and water. Biota All living organisms in a region or ecosystem. Biotransformation Conversion of a substance into other compounds by organisms; including biodegradation. Blackwater Water that contains waste of humans, animals or food. Blind spots Any place on a filter medium where fluids cannot flow through. Blinding A build-up of particles in a filter medium, that prevents fluids from flowing through. BOD5 The amount of dissolved oxygen consumed in five days by bacteria that perform biological degradation of organic matter. Boiling point The temperature at which the vapour pressure of a liquid equals the pressure of its surface. The liquid will than vaporize If the pressure of the liquid varies, the actual boiling point varies. For water the boiling point is 100 degrees Celsius. Bottled water Water that is sold in plastic containers for drinking water and/ or domestic use. Brackish water Water that is neither falls in the category of salt water, nor in the category of fresh water. It holds the middle between either one of the categories. Breakpoint chlorination Addition of chlorine to water until there is enough chlorine present for disinfection of water. Breakthrough Crack or break in a filter bed that allows the passage of floc or particulate matter through a filter. Brine Highly salty and heavily mineralised water, containing heavy metal and organic contaminants. Buffer A substance that reacts with hydrogen or hydroxyl ions in a solution, in order to prevent a change in pH. Cake Solid dewatered residue on a filter media after filtration. Calcium hypo chlorite A chemical that is widely used for water disinfection, for instance in swimming pools or water purification plants. It is especially useful because it is a stable dry powder and can be made into tablets. Candle filter A relatively coarse aperture filter, designed to retain a coat of filter medium on an extended surface. Capillary action Water that at some point rises higher than that portion of its surface, not in contact with the solid surface. This is due to adhesion, cohesion and surface tension where later touches a solid. Cappilary membranes Membranes about the thickness of a human hair, used for Reverse Osmosis, nanofiltration, ultrafiltration and microfiltrtion. Capillary zone Soil area above the water table where water can rise up slightly through the cohesive force of capillary action. Carcinogen Any dissolved pollutant that can induce cancer. Cartridge filter Disposable filter device that has a filter range of 0.1 micron to 100 microns. More info on cartridge filters Carbonates Chemical compounds related to carbon dioxide. Carbonate hardness Hardness of water caused by carbonate and bicarbonate by-products of calcium and magnesium. Catalyses Chemical that increases the rate of a reaction but does not take a direct part in the reaction, so that it is still intact after the reaction has taken place. Catch basin A sedimentation area designed to remove pollutants from runoff before being discharged into a stream or pond. Cathode A site in electrolysis where cations in solution are neutralized by electrons that plate out on the surface or produce a secondary reaction with water. Cation A negatively charged ion, resulting from dissociation of molecules in solution. Centrifugation A separation process, which uses the action of centrifugal force to promote accelerated settling of particles in a solid-liquid mixture. More info on centrifugation CFU Colony Forming Units. This is a measure that indicates the number of microrganisms in water. Check valve A valve that allows water to stream in one direction and will then close to prevent development of a back-flow. Chelating agents Organic compounds that have the ability to draw ion from their water solutions into soluble complexes. Chemical Oxygen Demand (COD) The amount of oxygen (measured in mg/L) that is consumed in the oxidation of organic and oxidasable inorganic matter, under test conditions. It is used to measure the total amount of organic and inorganic pollution in wastewater. Contrary to BOD, with COD practically all compounds are fully oxidized. Chemical pollution Introduction of chemical contaminants into a water body. Chemical weathering Dissolving of rock by exposure to rainwater, surface water, oxygen, and other gases in the atmosphere, and compounds secreted by organisms. Chloramines A chemical complex that consists of chlorine and ammonia. It serves as a water disinfectant in public water supplies in place of chlorine because chlorine can combine with organics to form dangerous reaction products. In which forms chloramines exist depends on the physical/ chemical properties of the water source. Chlorinated hydrocarbons Hydrocarbons that contain chlorine. These include a class of persistent insecticides that accumulate in the aquatic food chain. Among them are DDT, aldrin, dieldrin, heptachlor, chlordane, lindane, endrin, Mirex, hexachloride, and toxaphene. Chlorinated solvent An organic solvent containing chlorine atoms that is often used as aerosol spray container, in highway paint, and dry cleaning fluids. Chlorination A water purification process in which chlorine is added to water for disinfection, for the control of present microrganisms. It is also used in the oxidation of compound impurities in water. Chlorine-contact chamber The part of a water treatment plant where effluent is disinfected by chlorine. Clarity The clearness of a liquid. Coagulation Destabilisation of colloid particles by addition of a reactive chemical, called a coagulant. This happens through neutralization of the charges. More info on coagulation Coalescence Liquid particles in suspension that unite to create particles of a greater volume. Coastal zone Lands and waters near the coast, whose uses and ecology are affected by the sea. Coliform bacteria Bacteria that serve as indicators of pollution and pathogens when found in water. These are usually found in the intestinal tract of humans and other warm-blooded animals. Coliform index A rating of the purity of water based on a count of coliform bacteria. Collector sewers Pipes to collect and carry wastewater from individual sources to an interceptor sewer that will carry it to a treatment facility. Colloids Matter of very small particle size, in the range of 10-5 to 10-7 in diameter. Combined sewer A sewer system that carries both sewage and rain water runoff. Composite sample A series of water samples taken over a given period of time and weighted by flow rate. Compounds Two or more different elements held together in fixed proportions by attractive forces called chemical bonds. Concentrate The totality of different substances that are left behind in a filter medium after filtration. Concentration The amount of material dissolved in a unit of solution, expressed in mg/L. Concentration process The process of increasing the number of particles per unit volume of a solution, usually by evaporating the liquid. Condensate Water obtained by condensation of water vapour. Condensation The change of state from a gas to a liquid. Conductivity The amount of electricity the water can conduct. It is expressed in a chemical magnitude. Conduit A natural or artificial channel through which fluids may be transported. Consumptive water use Water removed from available supplies without return to a water resources system; water used in manufacturing, agriculture, and food preparation. Contact time The length of time a substance is in contact with a liquid, before it is removed by filtration or the occurrence of a chemical change. Contaminant Any foreign component in a substance, for example in water. Conventional sewer systems Systems that were traditionally used to collect municipal wastewater in gravity sewers and convey it to a central primary or secondary treatment plant, before discharge on receiving surface waters.  |
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