Triple A™ settler

Proven innovation for advanced pre-treatment of biological treatment plants.

Triple A™ is an innovative A-stage biological wastewater treatment technology. A technology based on two alternating reactors, switching between feeding, aeration and settling regimes. The technology allows for stable operation and results in no wash out of A-stage sludge and homogeneous fluidisation.

It’s a compact (about 2 hours hydraulic retention time, HRT) and simple to operate and maintain process.

Key feature is it’s ability to unload the biological treatment plant, due to extra removed carbon, nitrogen and phosphorus. It supports overall concepts to maximise biogas production and net-energy-producing plants.

By using a specific combination of physical and biological processes more ‘COD rich sludge’ can be gained and separated before bringing the wastewater to the bioreactors. Such solution has benefits if for example a sludge digester is part of the overall solution. A solution to maximise biogas production in the sludge (digestion) line.

Check this movie (3’17”) for a clear visualisation of the Triple A™ process.

It’s from AM-Team (specialists in process simulation) together with the inventor.

PROCESS-MECHANISMS

The brand ‚AAA‘ (Triple-A) stands for ‚Alternating Activated Adsorbtion‘. In conventional primary clarifiers purely physics is employed for settling particulate matter with an overall removal of organic matter by about 1/3. Triple A™ applies a flow-through sludge blanket to maximize redirection of organic carbon to anaerobic digestion, improving the energy balance of the plant.

It represents a compact pre-treatment unit that integrates all features of an A-stage in a dual-tank-configuration: biomass activation, biomass recycling, sludge wasting and waste sludge thickening. It is well suited to retrofit existing primary settlers at a hydraulic retention time of about 2 hours. Operational simplicity is the principle – the process cycle is fully air-driven without any mixers or pumps.

Main process goals:

  • Off-load the secondary or biological treatment, capacity increase
  • Removal of about 2/3 of COD and about 1/3 of N and P
  • Reduced aeration demand at increased methane yield – energy positive plant
  • Integrated thickening to about 5% solids for direct feed to digesters
  • Less cake-solids disposal due to high primary/secondary sludge ratio of about 0.75

PROCESS-IMPLEMENTATION

The system is operated typically in process cycles of 1 hour. Each cycle consists of five phases: inflow/outflow (30 min), compression, wasting, aeration and settling. Whereas the outflow is driven by the inflow, all other processes are air-driven (aeration & mixing, air-lift wasting, air-lock-decanting). Aeration is oxygen controlled at a standard set-point of 1 mg/L DO, the duration of sludge wasting is depending on the actual solids content in the activation/settling tank and automatically adjusted based on online TS-measurements.

Triple A™ can be implemented at greenfield and brownfield, small scale and large scale. The pictures below show the Triple A™ container configuration and the construction works for the conversion of the sludge-hopper-zones of existing primary clarifiers to the Triple A™ thickeners.

Benefits

  • Compact technology for minimised footprint.
  • Technologies made simple! Easy to operate. Low maintenance requirements.
  • More concentrated (primary) sludge separated.
  • Reduced aeration demand at increased methane yield – energy positive plant
  • Lower sludge disposal cost. Due to increased dewaterability of the overall primary and secondary sludge’s.

Related Applications

Related Technologies

  • UASB/EGSB to treat the effluent (for biogas production)
  • BIOCOS® or MBBR/FBBR to treat the effluent (for discharge/reuse)
  • anaerobic digester to digest the sludge (for biogas production)