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Port Macquarie Sewerage Scheme

The Port Macquarie Sewerage Scheme consists of a wastewater treatment plant (WwTP) and an extensive collection system.  The collection system includes a reticulation network of pipes and 76 pumping stations.  The WwTP is located at John Fraser Place, Port Macquarie.  

The plant has a capacity of 52,000 EP - or in other words, it has the capacity to treat  raw sewage equivalent to that generated by a population of 52,000 people.

Please refer to the brochures: " Wastewater - a User's Guide"1MB pdf(PDF, 1MB) and  "Wasterwater Systems - How the system works 'after the flush'".2MB pdf(PDF, 2MB)

Pre-Treatment

Port Macquarie WwTP uses rotoscreens along with a bypass channel fitted with manual screens to remove troublesome solids from the sewage before it is further treated.  Air deodorisation is also used to reduce the odour of the treatment plant.

Main Treatment

The Port Macquarie WwTP, like most other WwTPs in Australia, involves the process of Activated Sludge.  The particular method of Activated Sludge treatment that is used in Port Macquarie is Intermittently Decanted Extended Aeration.  This method is generally preferred in regional areas because of the high quality effluent produced along with its simplicity and cost effectiveness compared to other methods.  It is simple because the essential Activated Sludge processes of Aeration, Settling, Decanting and Sludge Removal are all carried out in a single tank rather than having separate vessels for each.  The Port Macquarie system uses three tanks and is designed for biological phosphorus removal.

After the wastewater is treated in the Intermittently Decanted Extended Aeration (IDEA) tanks, it is fed into two Effluent Balance Tanks, which remove a small amount of solids, but mostly serve to regulate the flow out of the treatment plant.

Even though the treated water from the IDEAs is very low in pollutants, Council's licence issued by the NSW Environmental Protection Authority (EPA) determines that effluent must be disinfected before being released.  The next stage in treating water after the IDEAs and balance tanks is disinfection by UV radiation.  To achieve this at Port Macquarie, the treated water is pumped across Lake Road to Detention Ponds.  It is then exposed to sunlight to enable the UV breakdown of any pathogens or other dangerous microbes still present in the wastewater.

After exiting the Detention Ponds, wastewater is further disinfected by a UV Radiation Unit, which works by passing wastewater through banks of UV lamps that kill bacteria in the water.  UV Radiation Units are widely considered to be an excellent way to thoroughly disinfect water and are also commonly used in the disinfection of drinking water.

Finally, the disinfected wastewater is discharged into Kooloonbung Creek downstream of the Lake Road Bridge.

Sludge Treatment

Sludge generated in the Port Macquarie WwTP is collected and treated in an aerated sludge storage lagoon on site.  There are also two backup sludge lagoons at Port Macquarie to handle extra sludge or should operation issues require.

The backup lagoons serve to hold the sludge whilst it is digested.  Once sludge has been digested, it is dewatered or dried out so it ends up as mostly dry solids.  This cake-like dry solid substance is called biosolids.

Generally however, the majority of biosolids produced at the WwTP are aerated in the aeration lagoon prior to being dewatered in the building using gravity drainage decks and centrifuges.  Aeration in the small lagoon is used to greatly reduce odours with the system.

Like all organic solids produced by wastewater treatment in the Hastings, the biosolids from Port Macquarie WwTP are transported to the Cairncross composting facility to be incorporated into compost.

 Please refer to the brochure:   "Wastewater - How it works at Port Macquarie Wastewater Treatment Plant".1MB pdf(PDF, 1MB)

This page was last updated on: 07 May 2019