A rigorous engineering comparison of the three dominant advanced biological treatment technologies to support technology selection for industrial and municipal wastewater projects.
Common questions on membrane-bioreactor design, flux, fouling, cleaning and operation — answered by our process engineers.
Read the MBR FAQCombines activated sludge treatment with ultrafiltration membranes (pore size 0.04–0.4 µm) to replace secondary clarification entirely. Mixed liquor suspended solids (MLSS) can be maintained at 8,000–18,000 mg/L, giving a very small bioreactor footprint. Effluent is essentially free of suspended solids (<1 mg/L TSS) and suitable for direct reuse. See our MBR membrane equipment.
A single tank performs fill, react, settle, decant, and idle cycles sequentially, eliminating the need for a secondary clarifier. Flexible operation allows nutrient removal (nitrification/denitrification) within the same vessel. MLSS typically 3,000–5,000 mg/L. Suited to variable-flow and batch-discharge industrial sites. See our SBR reactor equipment.
Biomass grows on plastic carrier media (fill fraction 30–70%) suspended in an aerated tank. No return sludge is required, and the biofilm concentration per m³ is high. Often used as a retrofit intensification of existing activated sludge plants. Robust against shock loads and temperature variation. See our MBBR reactor equipment.
MBR suits space-constrained sites requiring high-quality effluent. SBR is ideal for variable flows and batch industrial discharges. MBBR offers robust upgrade paths for overloaded activated sludge plants. We pilot test to confirm the optimal technology for your wastewater.
| Parameter | MBR | SBR | MBBR |
|---|---|---|---|
| Effluent TSS | <1 mg/L | 5–20 mg/L | 10–30 mg/L (with clarifier) |
| Effluent BOD | <5 mg/L | <10 mg/L | <15 mg/L |
| Nitrification | Excellent | Excellent | Excellent |
| Denitrification | Requires anoxic zone | Inherent in cycle | Requires anoxic stage |
| Phosphorus removal | Chemical dosing needed | Bio-P possible | Chemical dosing needed |
| MLSS concentration | 8,000–18,000 mg/L | 3,000–5,000 mg/L | High (attached biofilm) |
| Bioreactor footprint | Smallest | Medium | Small–medium |
| Secondary clarifier required | No | No | Yes (or DAF) |
| Sludge production | Low (long SRT) | Medium | Medium |
| Energy consumption | High (membrane aeration + permeation) | Medium | Medium |
| Capital cost | Highest | Medium | Medium–low |
| Membrane fouling risk | High — requires CIP protocol | None | None |
| Retrofit to existing CAS | Possible but complex | Difficult | Straightforward |
| Tolerance to shock loads | Moderate | Moderate | High |
| Operator skill required | High (membrane maintenance) | Medium | Low |
| Pathogen removal | 4–6 log (membrane barrier) | 2–3 log | 2–3 log |
| Suitable for water reuse | Yes (direct reuse quality) | With tertiary polishing | With tertiary polishing |
Where treated effluent is reused as process water, cooling make-up, or CIP recovery, MBR consistently delivers TSS <1 mg/L and BOD <5 mg/L without a separate tertiary step. Common in dairy, brewery, and pharmaceutical sectors.
SBR cycle timing can be adapted to match batch discharge schedules — common in food processing, slaughterhouses, and seasonal vegetable processing. Fill times accommodate variable inflow without hydraulic disturbance to biology.
Adding MBBR carriers to an existing activated sludge tank increases volumetric treatment capacity by 2–3× without new tanks. The most efficient route to compliance when consent limits tighten. See our plant upgrade services.
MBR eliminates the secondary clarifier (typically 30–50% of plant footprint) and allows high MLSS, making it the standard choice for urban WWTPs where land is the primary constraint.
When total nitrogen and total phosphorus consents require simultaneous nitrification, denitrification, and bio-P removal, the SBR cycle is the most operationally flexible tool, avoiding chemical dosing costs for nitrogen.
Biofilm on MBBR carriers maintains activity at lower temperatures than suspended growth, making it well-suited for remote or cold-climate containerised systems where start-up biomass is difficult to source.
Flat-sheet and hollow-fibre MBR membranes for industrial and municipal applications.
View MBR EquipmentSequencing batch reactors engineered for variable-flow industrial wastewater.
View SBR EquipmentMoving bed biofilm carriers and reactor packages from pilot to full scale.
View MBBR EquipmentCalculate bioreactor volume, sludge production, and oxygen demand for your application.
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Our expertise spans multiple industries with sector-specific water treatment solutions.