MBR Plant Sizing Calculator
Calculate membrane area, module count, bioreactor volume, aeration, and power for your Membrane Bioreactor (MBR) project. Based on submerged flat-sheet MBR design standards with real flux and MLSS parameters.
Enter Wastewater Parameters
MBR Technology: How It Works
A Membrane Bioreactor (MBR) combines conventional activated sludge biological treatment with membrane filtration in a single integrated system. Instead of a secondary clarifier for biomass separation (as in ASP or MBBR), MBR uses submerged ultrafiltration (UF) or microfiltration (MF) membranes — typically flat-sheet panels or hollow-fibre modules — immersed directly in the bioreactor.
The membranes provide an absolute barrier to bacteria, suspended solids, and most pathogens, producing consistently high-quality permeate regardless of inlet variability. This makes MBR permeate suitable as direct RO feed for ZLD systems, or for reuse applications where turbidity and TSS must be near zero.
MBR Design Parameters Explained
| Parameter | Typical Range | This Calculator |
|---|---|---|
| Net Permeate Flux (LMH) | 10–20 LMH | User input (default 15) |
| MLSS | 8,000–12,000 mg/L | 10,000 mg/L |
| HRT | 4–8 hours | 6 hours |
| SRT | 20–30 days | 25 days |
| Module Size (flat-sheet) | 20–30 m²/module | 25 m²/module |
| Yield (Y) | 0.35–0.45 | 0.40 |
Flux Selection: The Most Critical MBR Design Decision
Permeate flux is the single most important parameter in MBR design. Selecting too high a flux reduces capital cost (smaller membrane area) but dramatically increases fouling rate, chemical cleaning frequency, and membrane replacement cost. Selecting too low a flux is conservative and expensive.
For clean municipal or food processing wastewater (TSS <300 mg/L), fluxes of 15–18 LMH are sustainable with standard maintenance cleaning. For higher-TSS feeds from dairy, slaughterhouse, or textile industries, 10–13 LMH is safer. Industrial MBR designs should always include a 15–20% safety margin on membrane area to accommodate peak loads and fouling events.
MBR vs SBR vs MBBR: Which Technology Fits Your Project?
Each biological treatment technology has a different cost-performance-footprint profile:
| Technology | Footprint | Effluent BOD | Relative CAPEX | Best For |
|---|---|---|---|---|
| MBR | Smallest | <5 mg/L | Highest | Pharma, ZLD feed, space-constrained |
| SBR | Medium | <20 mg/L | Medium | F&B, batch flow, N removal |
| MBBR | Medium-large | <30 mg/L | Low-medium | Retrofit, budget-sensitive, continuous flow |
| ASP | Largest | <30 mg/L | Lowest | Municipal, large-scale simple wastewater |
Use our ETP Technology Selector for a guided recommendation based on your specific wastewater profile and constraints.
MBR for ZLD: The Preferred Pre-Treatment Technology
MBR has become the default pre-treatment technology ahead of RO in Zero Liquid Discharge (ZLD) systems. The reason is simple: MBR permeate (BOD <5 mg/L, TSS <2 mg/L, turbidity <1 NTU) is ideal RO feed. It reduces RO membrane fouling, extends cleaning intervals, and dramatically improves RO recovery rates compared to conventional biological + clarifier + filter combinations.
For industries under ZLD mandate — pharmaceutical plants, distilleries, textile dyeing units, and integrated food parks in water-scarce zones — MBR + RO is now the industry standard configuration in India. Spans Envirotech has designed and commissioned MBR-based ZLD systems across these sectors.
To understand full ZLD system cost, see our ZLD Cost Calculator.
Frequently Asked Questions
How do you calculate MBR membrane area?
Membrane area = Daily flow (L/hr) / Net flux (LMH). Where daily flow in L/hr = Flow (KLD) × 1000 / operating hours per day. For 100 KLD, 20 hrs/day, 15 LMH flux: area = 100,000/20/15 = 333 m². At 25 m²/module = 14 modules (round up).
What is the cost of an MBR plant in India?
MBR plant cost in India ranges from ₹55–120 lakhs for 50 KLD, ₹1.5–3 Crore for 100–200 KLD, and ₹3–8 Crore for larger plants up to 500 KLD. MBR costs 40–60% more than conventional MBBR for the same flow, but offers superior effluent quality and smaller footprint. Membrane replacement (every 7–10 years) is the main OPEX item.
Does MBR produce better effluent than MBBR?
Yes. MBR produces effluent with BOD <5 mg/L and TSS <2 mg/L consistently, regardless of load variability. MBBR with a secondary clarifier typically achieves BOD 20–30 mg/L. For CPCB discharge compliance, both are acceptable, but for water reuse or ZLD feed, MBR permeate quality is significantly better.
What is TMP in MBR and why does it matter?
TMP (Trans-Membrane Pressure) is the pressure difference across the membrane during filtration. Normal operating TMP for submerged MBR is 0.1–0.3 bar. Rising TMP indicates membrane fouling. When TMP exceeds 0.5 bar at design flux, it triggers chemical cleaning. Consistent high TMP at low flux indicates irreversible fouling requiring recovery cleaning or membrane replacement.
Can MBR treat high-TDS industrial wastewater?
MBR removes BOD, COD, TSS, and pathogens, but does NOT reduce TDS. TDS passes through UF/MF membranes. If your wastewater has high TDS (>2,000 mg/L) and discharge norms require TDS reduction, you need RO downstream of MBR. MBR + RO + MEE/MVR is the standard ZLD configuration for high-TDS industrial wastewater.
Ready to Design Your MBR System?
This tool gives planning-level estimates. Our MBR design team can prepare a detailed proposal with membrane vendor evaluation, P&ID, equipment list, and project cost.