Anaerobic digestion – The natural breakdown of organic materials into methane and carbon dioxide. This takes place naturally, or in an anaerobic digester – a vessel in which bacteria act without oxygen.
Antifoams – Chemical agents designed to control the wasteful formation of foam during industrial processes.
Charge neutralisation – Destabilisation mechanism where the positively charged metal coagulant is attracted to the negatively charged colloids, forming flocs.
Clarification – Process in which the large flocs containing much of the suspended matter sink to the bottom of the tank, so that the clear water overflows and can be further treated.
Coagulants – A substance which causes particles in a liquid to curdle and clot together, so that they can be easily removed from the liquid.
Colloidal material – Microscopically dispersed insoluble particles, which are suspended throughout another substance (e.g. water).
Defoamers – See Antifoams.
Dewatering – The removal of water from solid material through solid-liquid separation processes.
Effluent – An outflow or discharge of liquid waste or sewage.
Filtration – The process of filtering something, e.g. filtering small particles from water.
Floc – A mass of material formed in a fluid through the clumping of suspended particles.
Flocculants – A substance which promotes the clumping of fine particles into a floc, so that the floc may be easily removed from the water.
Flotation – When a floc floats to the top of a liquid (e.g. water).
Municipal wastewater – Sewage which is treated at a wastewater treatment plant.
Polyacrylamides – An acrylic resin that has the unique property of being soluble in water. The solutions they create have gel-like properties, making them perfect to use in flocculation.
Polymers – Any of a class of natural or synthetic substances composed of very large molecules, called macromolecules.
Potable water – Water safe enough for drinking and food preparation.
Precipitation – The creation of a solid from a solution.
Precipitated floc – A floc formed from precipitation.
Sedimentation – When particles in a liquid come out of suspension and settle to the bottom.
Sludge – A semi-solid ‘soupy’ material usually containing significant quantities of water.
Superabsorbents – Super-absorbent polymers with the ability to absorb vast amounts of water.
Supernatant – The liquid lying above a solid residue after crystallisation, precipitation, centrifugation, or other process.
Turbidity – The cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye.
Viscous – Having a thick, sticky consistency between solid and liquid.
Watercourse – The channel that a flowing body of water follows.
Water immiscible – Not forming a homogenous mixture when mixed, e.g. oil and water.
Water dispersible – Able to be distributed throughout water.
Wet classification – A process whereby particles are separated in water according to settling velocity differences.