Biological nutrient removal (BNR): Provides the main treatment process during which a population of naturally-occurring microorganisms feed on the nutrients in the wastewater. These organisms remove virtually all the dissolved organic matter and reducing the nitrogen content by more than 80 percent.
Directional drilling: This takes the place of digging trenches and can take a pipe directly from one point to another - up to several hundred metres away - with almost no surface disturbance. It is an environmentally-friendly technology that reduces and often completely avoids environmental impacts on land and aquatic environments.
Fine screening: Process to remove debris and unbiodegradable matter, allowing only particles smaller than about 2mm and dissolved material to pass through into the treatment process.
Grit removal: After screening to allow dense particles (sand, for example) to be settled and removed as solid waste, along with the screenings from the previous step. The solid waste will be taken by Citiwaste and disposed in the same manner as normal domestic rubbish.
Membrane bioreactor (MBR): Membranes act as a barrier to solids including bacteria, high molecular weight soluble organics and other microorganisms.
Micro-tunnelling: A computerised, steerable, controlled evacuation tunnelling method used for pipelines. The high accuracy required when installing wastewater pipelines, combined with work where minimum disruption is required, makes micro-tunnelling ideal for such projects.
Phosphorus removal: Facilitated by simultaneous addition of chemicals to the MBR. The chemicals are added at relatively low concentrations and do not interfere with the natural biological processes in the MBR.
Pumping station: Pumping stations form an essential part of the wastewater management network as they pump wastewater, transported from homes and businesses via underground pipelines, up hills and across flat terrain toward the city's wastewater treatment facilities.
Rising main: An underground pipe that carries wastewater from a pumping station to a main wastewater line.
Semi-permeable membranes: These remove all particles down to about 0.1 micron (1 micron is equal to 1/1000th of a millimetre). Virtually all bacteria and other pathogens (including some viruses) are removed in this manner, leaving only dissolved material in the treated wastewater.
Trenchless technology: Involves an underground pipeline constructed using horizontal directional drilling or microtunnelling. This technique makes construction and operation less disruptive to residents and the environment. All spoil removed from the tunnel is captured, filtered, and either recycled or disposed of appropriately. Once completed, a pipe is inserted into the tunnel to carry the flow of wastewater.