UNITANK Process
The UNITANK system operates similarly to a triple-ditch oxidation ditch, featuring three interconnected rectangular tanks with individual aeration and mixing systems. Wastewater can enter any tank, while the outer two tanks alternate as aeration/sedimentation zones (equipped with weirs/decanters and sludge discharge devices). The center tank remains permanently aerated.
Through spatiotemporal control, the system achieves aerobic, anoxic, and anaerobic conditions within a single cycle while maintaining continuous inflow. Unlike conventional SBR, UNITANK simplifies operation with:
- Fixed-level continuous operation (no water level fluctuations)
- No sludge recirculation required
- Flexible nutrient removal via inlet positioning
Refer to Figure 1-3 for the basic process flow.
1.Key Features of UNITANK
Hybrid Design Advantages
- Hydraulic Stability: Constant water level reduces demands on pipes/valves, lowering operational costs.
- Compact Footprint: 1/3–1/2 the space of oxidation ditches (no primary/secondary clarifiers or RAS systems).
- Flexible Aeration: Supports surface aerators (fixed weirs suffice, eliminating floating decanters).
- Precise Nutrient Control: Explicit separation of anaerobic/anoxic phases (vs. SBR's overlapping phases).
2.Performance Benefits
- Combines strengths of SBR, conventional activated sludge, and oxidation ditches while overcoming their limitations:
- Continuous inflow (vs. SBR's intermittency)
- Deep-tank design enables high space efficiency
- Full automation with minimal equipment (1/6–1/4 staff vs. oxidation ditches)
- Cost Savings: Capital investment ≈50% of oxidation ditches.
3.Comparative Advantages
DAT-IAT Process
The DAT-IAT process (Demand Aeration Tank-Intermittent Aeration Tank) is an advanced variant of SBR technology, consisting of two core compartments:
- DAT (Demand Aeration Tank): Continuously fed and aerated.
- IAT (Intermittent Aeration Tank): Performs cyclic aeration, settling, decanting,and sludge wasting.
Refer to Figure 1-4 for the process flow diagram.
1.Key Features of DAT-IAT Technology
(1) Enhanced Stability & Load Resistance
- DAT provides hydraulic equalization through continuous inflow/aeration, improving system stability.
- High MLSS concentration and extended sludge age in both DAT and IAT boost resilience to organic/toxic shock loads.
- IAT's adjustable cycles facilitate degradation of refractory organics.
(2) Compact & Simplified Design
- Integrated aeration-sedimentation eliminates primary/secondary clarifiers and sludge return systems.
- Aerobically stabilized sludge requires only thickening/dewatering (no digesters).
(3) Flexible Nutrient Removal
- Adjusting IAT's aeration/idle periods creates alternating aerobic/anoxic/anaerobic conditions for efficient N&P removal.
(4) Cost & Operational Efficiency
- Shared wall between DAT-IAT reduces civil costs and footprint.
- Fewer decanters needed vs. conventional SBR.
- Lower aeration demand: Continuous DAT aeration cuts blower capacity by ~30% vs. SBR.
- Simplified controls: No inflow valves (DAT's continuous feed reduces automation complexity).
2.Comparative Advantages
MSBR Process
The Modified Sequencing Batch Reactor (MSBR) integrates the advantages of conventional activated sludge and SBR technologies. It operates at a constant water level with a single-tank, multi-compartment design, eliminating the need for interconnecting pipes, pumps, and valves between multiple tanks. Functionally, the MSBR combines A²/O and SBR processes in series, achieving simultaneous nitrogen and phosphorus removal.
Refer to Figure 1-5 for the schematic flow diagram.
1.Key Features of MSBR Technology
(1)Enhanced Operational Efficiency
Continuous inflow through the anaerobic unit (not the SBR unit) improves hydraulic/organic shock load tolerance
Main aeration tank handles most oxygen demand, maximizing equipment utilization.
(2)Optimized Biomass Distribution
- Low-energy sludge and mixed liquor recirculation ensures uniform MLSS across compartments, elevating concentrations in continuous-flow zones.
(3)Innovative Flow Hydraulics
- A bottom baffle in the SBR compartment replaces horizontal flow with vertical upflow, leveraging dense sludge layers to:
- Filter suspended solids.
- Enhance denitrification via carbon source utilization.
- Yield high-concentration waste sludge (reducing discharge volume).
(4)Advanced Effluent Control
- Air-controlled weirs (vs. initial decanting) prevent suspended solids from entering effluent during aeration, ensuring low TSS in output.
(5)Superior Nutrient Removal
- High MLSS and sludge filtration layers boost organic carbon removal.
- Extended hydraulic retention time (HRT) ensures thorough nitrification, while settling-phase denitrification improves nitrogen removal.
(6)Phosphorus Removal Precision
- Multiple nitrate-blocking mechanisms:
- Alternating anoxic/aerobic phases in the SBR reduce nitrate in return sludge.
- Anoxic tank further denitrifies before sludge-water separation.
- Sludge concentration in the separation zone minimizes nitrate returning to anaerobic stage.
- Minimal recirculation flow preserves VFA concentration, effectively extending anaerobic HRT for robust phosphorus elimination.
2.Comparative Advantages
