World-Water - Model Triple A -Wastewater Treatment Settler Plant
Wastewater treatment plants looking to meet new, more stringent effluent requirements, improve their energy efficiency and increase treatment capacity can benefit from a biological active-settling technology. As a solution, we offer an innovative settler design that can easily be retrofitted to existing plant infrastructure.
Elevate Operations With Advanced Pre-Treatment
Conventional primary clarifiers take a purely physical approach to the settling of particulate matter, where nitrogen and phosphorus removal is minimal. The Triple A Settler (AAA) — an acronym for Alternating Activated Adsorption — applies a flow-through sludge blanket that maximizes the redirection of organic carbon to anaerobic digestion, increasing nitrogen and phosphorus removal while improving the secondary treatment energy balance and performance.
This innovative settler design boosts primary clarification while minimizing chemical and energy consumption.
Combined Design Elements Provide Optimized Performance
The Triple A settler consists of a compact pre-treatment unit that integrates all features of an A-stage with a dual-tank-configuration to offer biomass activation, biomass recycling, sludge wasting and waste sludge thickening. This combination of features makes AAA well-suited to retrofit existing primaries at a hydraulic retention time of approximately two hours. The process principle is operational simplicity — the entire process is fully air-driven with no mechanical mixers or pumps.
The process goals are:
- Increasing capacity by removing:
- approximately 60% of chemical oxygen demand (COD).
- approximately 20% of nitrogen.
- approximately 30% of phosphorus.
- Reducing aeration demand at an increased methane yield through carbon redirection.
- Providing a net zero and/or net positive treatment plant.
- Integrating thickening to approximately 5% solids to directly feed digesters.
- Reduce cake-solids disposal via a high primary/secondary sludge ratio of approximately 0.7.
Triple A was implemented at a brownfield facility at the Rottenburg wastewater treatment plant (WWTP) in Germany (46,000 PE). The process was retrofitted into existing tankage to help improve treatment capacity. The AAA system eliminated 66% COD (Figure 1) and 43% phosphorus on average and achieved an average total nitrogen elimination rate of 36%, as shown (Figure 2).