Longford Sewage Treatment Plant Official Opening

In light of environmental and capacity challenges with their aging existing plant, in 2018 TasWater engaged Aquatec Maxcon to design and construct the new Longford STP – at the core of our design was Haskoning’s Nereda process. This was Aquatec Maxcon’s (and Australia’s) second Nereda Plant after the successful handover of Kingaroy STP selected through ECI.

With a combined catchment of the Longford township sewerage system as well as a neighbouring industrial wastewater catchment, the day one load to the new Longford STP was 2.5MLD (albeit a significantly stronger 2.5MLD than a regular sewerage catchment), and the design caters to the future catchment growth.

The full treatment process consists of:

• A package inlet works (including band screens and grit removal) on the domestic influent
• A dissolved air flotation process on the industrial influent
• Influent and effluent flow balancing
• Two Nereda bioreactors utilising aerobic granular sludge
• Pressure media filtration to meet EPA licence requirements.
• UV Disinfection
• A package gravity thickener for the bioreactor waste sludge
• Anaerobic digestion of the DAF primary sludge and bioreactor secondary sludge
• Rotary screw presses & sludge Conveyors for digested sludge dewatering
• A BioAir packaged odour control facility for foul air extraction and treatment

The key design parameters were:

• 4MLD future combined influent capacity
• Effluent Total Nitrogen (TN) <8Effluent Total Phosphorus (TP) <2 (biological P-removal supplemented by chemical dosing)
• Class B Biosolids Stabilisation from the Anaerobic Digester
• <2 Odour Units (OU) at the nearest receptors
• The plant successfully treats the combined domestic and industrial influent, and the biomass in the Nereda bioreactors has seen high levels of granulation since seeding.
• Aquatec Maxcon and Haskoning continue to provide ongoing process support for the Nereda process to the TasWater operations team since handing over the plant in 2023.