Practical calculators and engineering references for biological process design, membrane-system sizing, equipment selection, and MBR project planning.
Move from verified project inputs to coordinated biological, membrane, equipment, chemical, sludge, and post-treatment checks.
Use the sequence below to understand which calculation should come first, what information it needs, and where its outputs are used next. The sequence supports preliminary engineering; it does not replace wastewater characterization, pilot testing, membrane supplier confirmation, detailed design, or permit review.
Establish the design envelope before selecting equipment or biological setpoints.
Check whether equalization, transfer pumping, elevations, and peak-flow routing support the process.
Translate loading and treatment objectives into biomass, oxygen, nutrient-removal, and alkalinity checks.
Check whether oxygen, carbon, alkalinity, and recycle assumptions are mutually consistent.
Use the design flow and membrane basis to determine online area, installed area, and duty/standby trains.
Combine membrane and biological air demand with hydraulic and chemical loads, then carry the energy and equipment basis into CAPEX, OPEX, LCC, and NPV screening.
Check chemical storage, sludge production, wasting, dewatering, and sidestream return effects.
Match the final barrier, monitoring, contingency, and review plan to the intended discharge or reuse application.
Use these relationships to keep assumptions traceable. A calculated result is an input to the next screening step only after its basis and units have been checked.
| Upstream result | Primary downstream use | What to verify before hand-off |
|---|---|---|
| Equalization volume and transfer-pump duty | Hydraulic profile and biological design flow | Peak routing, operating level, pump control, bypass, and actual tank geometry |
| MLVSS/MLSS, SRT, reactor volume, oxygen, alkalinity, and carbon demand | Biological basin zoning, aeration, recycle, and chemical systems | Temperature, influent variability, measured solids, treatment objective, and mass-balance closure |
| Online membrane area, installed area, duty trains, standby trains, and design flux | Air scour, energy, equipment, and lifecycle cost | Membrane OEM basis, peak flow, recovery, temperature, train isolation, and standby philosophy |
| Air demand, blower power, pumping energy, and chemical demand | Energy and operating cost, then CAPEX, OPEX, LCC, and NPV screening | Tariff, operating hours, equipment efficiency, membrane replacement interval, chemical price, escalation, discount rate, and currency basis |
| Sludge production, WAS, polymer, cake, and return liquor | Dewatering, storage, sidestream, and downstream loading | Sampling method, dewatering equipment, polymer selection, return timing, and disposal route |
| Post-treatment dose, contact volume, UV duty, and storage | Reuse monitoring, residual control, contingency, and final design review | End-use criteria, local requirements, disinfection credit, storage retention, and failure response |
