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Glossary definitions

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AbsorbTo physically or chemically assimilate a substance and include it in another; to take up gases, water, nutrients or other substances e.g. by soils or plants.
Absorption trench The disposal field of a conventional domestic on-site effluent disposal system; an excavated area, filled with gravel with a light cover of soil from which water from a perforated pipe from a septic tank can evaporate and percolate into the surrounding soil.
AcidA substance containing more H+ ions than OH- ions in solution; a condition where the pH is below 7, where the activity of the H+ ion exceeds that of hydroxyl OH- ions.
Activated carbon High porosity, high surface area carbon obtained by burning organic matter in the absence of air, which possess a high capacity to remove trace and soluble components from solution; used to remove impurities causing odour and undesirable taste from drinking water by absorbing gases and various organic and inorganic molecules. Also used for removing cyanobacterial toxins from drinking water.
Activated sludge A rich mixture of bacteria and mineral substances that has been through a reactor tank and which is to be reintroduced, aerated and mixed with the incoming sewage; a type of sewage treatment plant in which the above process is used to break down organic matter and nitrogen compounds.
Acute poison A toxin that quickly causes a crisis situation to be reached; not chronic
AdsorbAttach a substance to the surface of a liquid or solid e.g. cations to a negatively charged clay or other colloidal material; retain water, ions or exchangeable bases on a colloidal surface.
AEAM Adaptive Environmental Assessment and Management
AerationExposure of a material to air so that dissolved gases may be removed; the process by which air is added to a substance or exchanged with an existing atmosphere.
AerobicAdapted to the presence of oxygen; growing or occurring only in the presence of molecularoxygen; having molecular oxygen as part of the environment; bacteria that require oxygen in order to survive and multiply.
Aerobic digestion Breakdown of organic matter in a liquid medium in the presence of oxygen or air.
AerosolA colloidal system of solid or liquid particles dispersed in a gas; very fine particles in the atmosphere e.g. smoke, fog, smog.
AgingThe progressive breakdown of organic materials through the cumulative effects of irreversible physiochemical processes over a period of time; nutrient and sediment build up in water storages over time.
Algae Simple photosynthetic aquatic or moist habitat plants, semicellular or in colonies or filaments,some free-floating or having motile cells with flagella, others attached to various substrates or having symbiotic relationship with plants or animals.
Algal bloom A rapid increase in the mass of one or more algae or cyanobacteria (blue-green algae) in a water body, usually in response to a change in its flow, light, temperature or nutrient status.
AlkalineContaining or releasing an excess of hydroxyl (OH-) ions over hydrogen (H+) ions; capacity to reduce or neutralise acidity; a soil or solution with a pH>7.
AllocationThe announced percentage of water entitlement that can be used in a particular season. This is normally known as seasonal water allocation and is computed based on available in-storage volume plus 1/100 year inflows.
AlumHydrated double salt of aluminium and potassium sulphates; a general term used for aluminium sulphate, used as a coagulant in water treatment; the reaction product of sulphuric acid and alumina or bauxite.
Ammonia A colourless alkaline gas NH3, produced synthetically in a modified Haber process from nitrogen in air and hydrogen from methane (natural gas) using catalysts at high temperature and pressure.
Anaerobic Lacking air or molecular oxygen; living or functioning in the absence of air or free oxygen; capable of survival only in the absence of oxygen; bacteria living in such conditions
Anaerobic digestion Decomposition of oxygenic materials under conditions of low air or oxygen supply.
AnoxicLacking dissolved oxygen; a condition in which oxygen is deficient or absent or exists only in a combined form
Antecedent storage condition The level of water within a wetland prior to the onset of the next inflow event
AnthropogenicProduced or caused by humans
Aquatic macrophyte A large plant capable of living in water or periodically inundated habitats
AquiferA layer of porous rock that both stores water and allows it to percolate through; underground rocks, gravels or coarse sediments capable of storing water, which may be recovered for irrigation or other consumptive uses.
Aquifer recharge Build up of the water level in a natural underground storage
Aquifer storage and recovery (ASR)The storage of water through wells installed into aquifers, with subsequent retrieval from the same wells during demand for the stored water
Artificial wetland A constructed habitat with either static or running water and aquatic or terrestrial vegetation, with the objective of directly reducing contaminants in the water or creating conditions for this to occur.
Australian Drinking Water GuidelinesPortion of the National Water Quality Management Strategy (1996) dealing with the physical, chemical and biological components of water for human consumption.
Average Dry Weather Flow (ADWF)The amount of water moving downstream in a catchment during the dry season; the average daily volume of wastewater entering a sewage treatment plant in dry weather.




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