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The EPCO Australia Packaged Extended Aeration Sewage Treatment Plant (PSTP) was developed in Australia in 1961 to meet the demands of smaller or isolated communities for the complete purification of domestic sewage to a degree allowing discharge to local water courses, irrigation and reuse.
The incoming raw sewage is screened and mixed with returned activated sludge from the settling chamber. This mixture drops into the aeration chamber, where interaction with oxygen produces activated sludge bacteria that consume the pollutants in the sewage stream. This stage of treatment takes approximately 24 hours.
The aerated sludge, now called Mixed Liquor Suspended Solids (MLSS), moves on to the settling chamber via a flow regulating device, where clari fication takes place. The settled sludge is returned to the inlet end of the plant to continue the treatment process. The surface scum collected by the scum skimming mechanism is also returned to the inlet end of the plant for retreatment.
The clarified effluent flows on to disinfection and tertiary processes as needed, to achieve the final discharge quality set by the local statutory authorities. Packaged plants can be designed to suit 50 persons to 5000 persons and can be located in ground or above. They have a number of advantages in that they are compact, very reliable and are simple to operate and maintain.
The EPCO Australia PSTP can produce effluents ranging in quality from the basic 20mg/l BOD, 30mg/l Suspended Solids ('D' Class effluent - Queensland Water Recycling Guidelines 2005), to the polished effluents having bacterial counts of less than 1 coli forming units (cfu) and turbidity levels of less than 2 NTU (A & A+ Class - Queensland Water Recycling Guidelines 2005). Such high quality effluents are suitable for specific reuse purposes.
 Since the initial development, hundreds of EPCO Australia Packaged Sewage Treatment Plants have found use in innumerable situations in small towns, hotels, mine sites, oil fields and holiday resorts, in climatic conditions ranging from the snow covered Australian Alps to Tropical North Queensland, South East Asia and the hot deserts of the Middle East.
Remote sites such as this Chevron Oil site in the PNG highlands (pictured below right) often require installation by local unskilled labour in extreme conditions with limited access and tooling. The use of airborne cranage such as the Vertol helicopter shown in the background is common. 
The hopper for this plant was assembled in an inverted position and flipped over once complete.
The two basic plant types are the rectangular design for lower capacities and circular plants for higher ranges.
Just as the installation locations are varied, the available options also depend on the application.
 Available Options:
- Bolted or welded steel tanks
- Trailer mounting for small sizes
- Concrete Tank
- Tertiary Filters (media, membrane or disc)
- Comminutors or mechanical screening
- Tablet Chlorine Disinfection
- UV Disinfection
- Flow Balance Tanks
- Plant Operation & NATA testing
- Operator training
Last Updated ( Friday, 04 June 2010 00:26 )
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