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) <8, Effluent 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.
