Case Study of Brewery Wastewater Treatment -
CIRCOX Process at a Shanghai Company
This brewery wastewater treatment system has a capacity of 4,800 m³/day, with the process flow shown in Figure 1-1.
Key Treatment Units
1. IC (Internal Circulation) Reactor
Developed in the 1980s by Paques (Netherlands) based on UASB principles, the IC reactor consists of:
- Mixing zone
- Sludge expansion bed
- Polishing zone
- Recirculation system
Advantages over conventional anaerobic processes:
✔ Compact design (Height/Diameter ratio: 16–25 m tall, small footprint)
✔ Low sludge production (~1% of influent COD, easy dewatering)
✔ Energy-efficient (Self-circulating via biogas lift, no external mixing power)
✔ Closed system (Controls VOC emissions; biogas: 70–80% CH₄, 20–30% CO₂)
2. CIRCOX(Closed Internal ReCirculation OXidation) Reactor
A vertical dual-cylinder aerobic biofilm reactor:
- Inner riser tube: Water + compressed air flow upward, forming biofilm on carrier media (fine sand-like material).
- Outer downcomer: Settled sludge returns to the reactor base.
- "Cap-shaped" top section (diameter expanded by ~1/3) for three-phase separation (biogas/water/sludge).
Key features:
- Excellent sludge settling properties (minimal biomass washout)
- High treatment efficiency with 15–25 g/L VSS concentration
Process Flow (Refer to Fig. 1-1)
- Wastewater collection → Inlet well → Pump → Rotary screen (with online pH/temperature monitoring).
- Buffer tank (submersible mixer for homogenization) → Pre-acidification tank (3h HRT; partial VFA conversion + pH/nutrient adjustment).
- IC reactor (2h HRT; COD load: 15 kg/(m³·d)) → CIRCOX reactor (1.5h HRT; COD load: 6 kg/(m³·d)).
- Lamella clarifier (flocculant dosing) → Effluent tank (partial reuse/discharge).
- Sludge → Dewatering system.
- Exhaust gas treatment: Centrifugal fan → Scrubber tower (using treated effluent + dilute alkali).
Design Parameters
| Table 1-1 Main Treatment Unit Design Parameters | ||||
| Unit | Dimensions | HRT | COD Loading | Notes |
| Pre-acidification | Ø6m × H21m | 3h | - | pH/nutrient adjustment |
| IC reactor | Ø5m × H20.5m | 2h | 15 kg/(m³·d) | Biogas yield: 0.35 m³/kg CODₜₕ |
| CIRCOX reactor | Ø5m (base)–Ø8m (top) × H18.5m | 1.5h | 6 kg/(m³·d) | VSS: 15–25 g/L |
Performance
- Effluent quality (Table 1-2): Meets all discharge standards.
- Automation: Fully automated control (IC/CIRCOX core components imported from the Netherlands).
| Table 1-2 Treatment Performance of a Brewery Wastewater Plant in Shanghai |
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| Parameter | Influent | Effluent | ||
| Average | Range | Average | Range | |
| COD (mg/L) | 2000 | 1000-3000 | 78 | 50-100 |
| BOD₅(mg/L) | 1250 | 600-1875 | ≤30 | - |
| SS/(mg/L) | 500 | 100-600 | 50 | 10-100 |
| NH₄⁺-N (mg/L) | 30 | 12-45 | 10 | 5-15 |
| Phosphate (mg/L) | - | 10-30 | - | - |
| pH | 7.5 | 4-10 | 7.5 | 6-9 |
| Temperature (°C) | 37 | 30-50 | ＜40 | - |
Advantages of IC + CIRCOX combo:
- Compact footprint
- Odor-free operation
- Low sludge yield
- High treatment efficiency