Available
MBR Quick Sizing Calculator
Estimate a solids-balanced bioreactor volume, calculated HRT, membrane area, peak flow, and preliminary process indicators.
Membrane Bioreactor Biological Process Calculators
Use this catalogue as the biological-design branch of the MBR Design Tools workflow. Start with flow and solids assumptions, then move through nutrient removal, aeration, membrane interface, sludge, cost, and post-treatment checks. Each tool exposes its governing equations and assumptions for review before detailed process modelling.
Preferred inputsValidated flow, loading, temperature, laboratory data, as-built volumes, and measured solids.
Design assumptionsHRT, SRT, yield, decay, flux, recycle, oxygen-transfer, and treatment targets.
OEM inputsMembrane flux, air scour, train arrangement, cleaning, and equipment limits.
OutputsVolumes, areas, trains, oxygen, chemicals, sludge, energy, and hand-off values.
1. Flow, hydraulic, and preliminary sizing basis
Establish the flow envelope, equalization, pumping, and first-pass reactor and membrane sizing basis before making detailed biological selections.
Open calculator →
Available
Equalization Tank Sizing & Transfer Pumping Calculator
Screen cumulative balancing storage, equalized discharge flow, peak-flow attenuation, transfer-pump power, and annual transfer energy from a transparent daily flow pattern.
Available
Hydraulic Profile & Pumping Calculator
Screen pipe velocity, Hazen–Williams friction, fitting loss, total dynamic head, preliminary pump power, motor margin, and annual pumping energy.
Available
Membrane Flux, Area & Train Sizing Calculator
Screen net design flux, module area, membrane trains, N+1 availability, air-scour hand-off, and flux-regulated train dispatch.
2. Biomass and solids basis
Translate reactor volume, loading, solids concentration, SRT, wasting, and sludge production into a traceable solids balance.
Available
Biomass Concentration Calculator
Estimate steady-state MLVSS and MLSS concentration from removed BOD, SRT, HRT, biomass yield, endogenous decay, and solids fraction assumptions.
Available
Solids Balance & SRT Calculator
Calculate biological solids inventory, SRT, wasting-rate targets, and the effect of effluent solids losses using a transparent mass balance.
Available
Sludge Production & Dewatering Calculator
Extend excess solids into dewatering feed, cake mass and volume, liquor return, polymer demand, operating duty, annual cake, and preliminary storage.
3. Nitrification, denitrification, phosphorus, and alkalinity
Use temperature, ammonia, nitrate, phosphorus, recycle, carbon, and alkalinity assumptions to test nutrient-removal feasibility and chemical demand.
Available
Nitrification Kinetics & Cold-Weather Minimum-SRT Calculator
Check temperature-corrected nitrifier growth, theoretical and safety-adjusted minimum SRT, selected-SRT margin, ammonia loading, oxygen, and alkalinity.
Available
Nitrogen Removal Calculator
Estimate ammonia nitrification, nitrate denitrification, oxygen and alkalinity effects, carbon demand, and preliminary anoxic-zone volume.
Available
External Carbon Source Dosing & Post-Anoxic Sizing Calculator
Size supplementary liquid-carbon demand, product feed, storage, post-anoxic hydraulics, and alkalinity recovery for nitrate polishing.
Available
Internal Recycle / Anoxic Zone Calculator
Estimate internal mixed-liquor recycle, nitrate-N removal load, and preliminary anoxic-zone volume for MLE and pre-denitrification MBR systems.
Available
Phosphorus Removal & Chemical Dosing Calculator
Estimate total-phosphorus removal and preliminary ferric chloride or alum product dose after selected biological phosphorus removal.
Available
Alkalinity Requirement Calculator
Estimate alkalinity demand and residual alkalinity associated with biological nitrification, and calculate supplemental chemical dosing.
4. Aeration and membrane interface
Connect biological oxygen demand, basin zoning, membrane area, air scour, and operating energy. Use supplier data and actual air-system conditions for final selection.
Available
Aeration System & Basin Zoning Calculator
Screen aerobic and anoxic volumes, biological oxygen demand, field oxygen-transfer efficiency, peak airflow, and thermodynamic isentropic blower power.
Available
Membrane Air-Scour Demand Calculator
Calculate full-duty and time-weighted membrane air demand from active train area, SADm, scour sequencing, altitude, and inlet-air conditions.
Available
MBR Energy & Operating Cost Calculator
Aggregate biological aeration, membrane air scour, pumping, chemicals, membrane replacement, sludge, labour, and fixed costs into annual energy and direct-OPEX screens.
5. Cleaning, permeate, and post-treatment
Check membrane cleaning demand, permeate indicators, and the final disinfection barrier after the biological and membrane basis is established.
Available
Membrane Cleaning & CIP Chemical Dosing Calculator
Screen sequential membrane-cleaning solution make-up, commercial product dose, annual chemical demand, cleaning water, and direct chemical cost.
Available
Effluent Permeate BOD Level Calculator
Estimate permeate BOD from soluble and particulate BOD fractions, biological-removal assumptions, and membrane retention of residual particulates.
Available
UV Disinfection Sizing & Chlorination Contact-Time Calculator
Size validated UV-reactor duty and chlorination product demand, T10, CT, and preliminary contact-basin volume for MBR permeate.
Biological calculator hand-off map
Use each result in the next check only after confirming units, basis, sampling quality, and whether the value is measured, assumed, OEM-supplied, or calculated.
| Upstream result | Next use | Check before hand-off |
|---|---|---|
| Equalized flow and transfer-pump duty | Hydraulic profile, reactor sizing, and design flow | Peak routing, operating levels, pump control, bypass, and actual tank geometry |
| Reactor volume, MLSS/MLVSS, SRT, yield, and decay | Solids inventory, wasting, nitrification, and sludge production | Measured solids, temperature, load variability, and mass-balance closure |
| Nitrification and nitrogen-removal demand | Alkalinity, carbon, internal recycle, oxygen, and anoxic-zone checks | Ammonia, nitrate, alkalinity, pH, temperature, and treatment objectives |
| Online membrane area, installed area, trains, and flux | Air scour, energy, cleaning, and lifecycle-cost screens | Membrane OEM basis, peak flow, recovery, temperature, isolation, and standby philosophy |
| Sludge production, WAS, polymer, cake, and return liquor | Dewatering, storage, sidestream, and downstream biological loading | Sampling method, equipment, polymer selection, return timing, and disposal route |
| Permeate quality and disinfection duty | Reuse monitoring, residual control, storage, and contingency | End-use criteria, local requirements, validation basis, and failure response |
Scope boundary: These calculators support preliminary engineering and education. Confirm process guarantees, membrane limits, chemical compatibility, structural design, controls, safety, regulatory conditions, and final equipment selection with the responsible design team.
Design note: Biological systems are dynamic. Seasonal load, temperature, influent variability, membrane configuration, oxygen-transfer capability, actual solids losses, and permit requirements must be considered in detailed design.
How to use these calculators responsibly
Each calculator is a transparent preliminary screen, not a substitute for a process model, pilot or bench testing, OEM data, permit criteria, or qualified engineering review. Use measured site inputs where available, record units and assumptions, and check the linked method and limitations on the individual calculator page.
- Traceability: equations, input definitions, source basis, and known exclusions are documented on each tool page.
- Validation: compare results with representative laboratory/plant data, supplier curves or product specifications, and applicable jurisdictional requirements.
- Professional boundary: a numerical result is not evidence of sustainable operation, treatment compliance, equipment selection, or safety approval.
Documentation revision: 2026-10-02. By: mbr-network.com. Please retain a dated calculation record when a result informs a design discussion.