PFAS-Ready and Future-Proof: Biological Innovation in Leachate Management

Aerofloat designed a leachate treatment plant (LTP) for a closed, unlined landfill site in Queensland. The site was generating approximately 50 kilolitres of leachate per day that required treatment prior to being discharged to the sewer network. The raw leachate contained elevated concentrations of several contaminants, including ammonia and PFAS, which needed to be reduced to acceptable limits to comply with trade waste regulations.

Leachate quality from the site was complex and varied over time. Aerofloat designed and built a LTP to reduce the volume of leachate stored within the landfill mass and ensure treated effluent met all environmental compliance targets. The treatment plant design allowed for continual operations for the next 10 years and incorporated a biological process for nutrient removal, as well as an adsorption process for the reduction of PFAS prior to discharge.

Aerofloat delivered a cost-effective biological treatment solution tailored to the required parameters, ensuring the plant could reliably meet discharge criteria and support long-term environmental management of the site.

Aerofloat designed, built and commissioned a robust, fully automated leachate treatment plant for the Queensland site using a biological process that consisted of an upfront anoxic reactor (AR), followed by a nitrifying reactor (NR), and concluding with a sequence batch reactor (SBR). This process configuration was carefully engineered to achieve advanced nitrogen removal through two-stage nitrification and denitrification, facilitated by significant internal recycle flows. Recycled activated sludge (RAS) recirculation ensured uniform MLSS concentrations across all three reactors and enhanced overall biological performance.

Unlike conventional designs, which use a pumped RAS loop from the SBR back to the anoxic reactor, Aerofloat’s innovative approach pumped forward from the AR to the NR, allowing the NR to overflow RAS back to the AR under gravity. The transition between cycles in the SBR was controlled by the level rise in the AR, ensuring efficient process timing and minimised operator intervention.

The SBR operated on an aerate/mix/settle/decant cycle, controlled via DO, ORP, and time-based logic. Intermittent blower operation during the aeration period reduced over-aeration and supported in-reactor denitrification, especially during low-flow periods. ALS decanting technology was used to remove treated effluent from the SBR and transfer it to a treated effluent storage tank. Waste sludge was pumped to sewer as the sludge production was low enough to still meet the discharge suspended solids criteria, removing the requirement for a site-based sludge management system.

Aerofloat met the client’s requirements for a PFAS removal system including granular activated carbon adsorption with upfront multi-media filtration, given PFAS removal was a requirement for sewer discharge. Aerofloat’s system was housed in fibreglass deep-bed filtration vessels with capabilities for automatic back-washing and forward-flushing. Aerofloat included automated HMI system controls to ensure 24-hour system surveillance for the client.

This integrated biological solution with filtration and adsorption capabilities, backed by remote monitoring and operational support, delivered a technically sound, reliable, and environmentally sustainable outcome for leachate treatment at the Queensland site.

Aerofloat’s solution provided the client with a technically sound, cost-effective, and scalable treatment system for managing leachate from the closed landfill. The system ensured operational stability through hydraulic buffering, complete automation, and real-time monitoring. Regulatory compliance was supported by advanced biological treatment processes that significantly reduced nitrogen levels. The activated carbon process ensured PFAS reduction that was compliant with discharge requirements. The treatment plant was fully automated and remotely monitored, with Aerofloat providing six months of post-commissioning remote and phone support to ensure seamless operation.