Biological Mass Balance
Track BOD removal, biomass growth, decay, volatile/inorganic solids, and net sludge production.
Engineering Calculation Module
Activated Sludge System
Design Calculation
Design and evaluate a conventional activated sludge system using a structured Excel workflow for biological loading, reactor sizing, solids production, sludge wasting, oxygen demand, aeration equipment, and secondary clarifier design.
BIO
Biological Process DesignFrom BOD removal through biomass and sludge production.
O₂
Aeration DesignMechanical aeration and diffused-air alternatives.
RAS
RAS / WAS ReviewReturn and waste activated sludge calculations.
✓
Secondary ClarifierSettling coefficients, HLR/SLR, geometry and weir checks.
What This Module Helps You Design
Use one connected process calculation from influent and primary-treatment basis through biological reactor sizing, sludge production, oxygen demand, aeration equipment, RAS/WAS handling, and secondary clarification. The workbook is intended for preliminary conventional activated sludge system design and engineering review.
Reactor & Aeration
Size reactor volume and evaluate HRT, F/M, SRT, oxygen demand, and aeration power.
Clarifier Design
Evaluate settling behavior, hydraulic and solids loading, basin diameter, depth, HRT, and weir loading.
Calculation Coverage
A connected activated-sludge process workflow from influent loading to biological reactor, aeration, sludge recycle/wasting, and final clarification.
Influent & Primary Basis
Flow, BOD₅, suspended solids, TKN, and upstream primary-treatment removal assumptions.
Substrate Removal
Soluble/particulate effluent BOD, biological BOD removal, and substrate utilization.
Biomass & Solids
Biomass growth, endogenous decay, VSS/SS balance, and net solids production.
Reactor Sizing
Total reactor volume, number of reactors, plan dimensions, liquid depth, and HRT.
Operating Ratios
MLVSS, MLSS, F/M ratio, sludge age/SRT, and reactor VSS/SS review.
RAS & WAS
Return sludge concentration, return ratio, RAS flow, and waste sludge withdrawal from the RAS line.
Oxygen Requirement
Carbonaceous, endogenous, and nitrification oxygen demand with field-condition corrections.
Aeration Equipment
Mechanical aeration power and diffused-air alternative airflow/blower power.
Secondary Clarifier
Settleability coefficients, HLR/SLR, area, diameter, depth, HRT, and weir loading.
Engineering Workflow
The workbook keeps biological, hydraulic, sludge, and equipment calculations connected in one reviewable sequence.
Influent & Primary Basis
Define load entering biological treatment.
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Aeration Reactor
Size biomass inventory, sludge age, HRT, and oxygen demand.
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Secondary Clarifier
Separate solids and establish RAS/WAS recycle and wasting basis.
Workbook Preview
Actual screenshots from the Activated Sludge Design workbook. The preview focuses on the system dashboard and the final design output summary so the workbook structure remains clear without exposing unnecessary calculation detail.
Designed for Engineering Review
Activated sludge design involves several linked calculations. AIDIA keeps the assumptions, intermediate balances, equipment sizing, and process checks visible in one workflow.
| Design Area | Key Review Output | Engineering Purpose |
|---|---|---|
| Biological loading | BOD and solids balance | Establish reactor substrate and solids basis |
| Reactor operation | MLSS / MLVSS, SRT, HRT, F/M | Review biomass inventory and operating regime |
| Sludge handling | RAS and WAS flow | Maintain reactor solids and waste net production |
| Aeration | Field O₂ demand, SOTR, power / airflow | Translate process demand into equipment duty |
| Secondary clarification | HLR, SLR, diameter, depth, HRT | Verify solids-liquid separation capacity |
No Black Box
Follow the calculation from influent loading to final equipment duty rather than relying on a single unexplained output.
Q
Inputs
- Flow & wastewater quality
- Primary removal basis
- Biological coefficients
- Operating targets
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BIO
Process Calculation
- BOD removal
- Biomass & solids
- Oxygen demand
- Clarifier loading
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▦
Output
- Reactor dimensions
- Aeration duty
- RAS / WAS
- Clarifier sizing
Built-in Design Checks
Selected operating and geometry checks are incorporated into the workbook. Detailed numerical criteria remain inside the purchased module.
| Review Item | Workbook Check | Status Style |
|---|---|---|
| Sludge age / SRT | Compared with adopted operating range | PASS / REVIEW |
| MLVSS / MLSS | Reactor biomass concentration review | PASS / REVIEW |
| F/M and HRT | Biological operating check | PASS / REVIEW |
| Oxygen transfer / installed aeration | Process duty vs adopted equipment capacity | PASS / REVIEW |
| Clarifier hydraulic & solids loading | Loading and geometry review | PASS / REVIEW |
What's Included
A standardized AIDIA workbook structure for biological process design, documentation, and review.
README
Purpose, use instructions, calculation basis, and engineering responsibility.
Cover
Project identity, document information, and revision fields.
Calculation
Biological process, sludge, oxygen, aeration, and clarifier calculations.
Dashboard
Process flow, mass balance, unit dimensions, oxygen duty, and equipment summary.
Design Criteria
Activated sludge and settling criteria used for preliminary review.
AIDIA Helps With
- Preliminary conventional activated sludge design
- Biological reactor and solids balance
- Oxygen demand and aeration equipment duty
- RAS/WAS and secondary clarifier calculations
- Structured engineering review and documentation
AIDIA Does Not Replace
- Project-specific biological treatability evaluation
- Regulatory and client-specific requirements
- Detailed vendor equipment selection
- Advanced process simulation / CFD where required
- Professional engineering approval
Related Modules
Explore AIDIA modules that connect naturally with biological wastewater treatment.
Start with a structured activated sludge system calculation.
Bring biological loading, reactor sizing, sludge production, oxygen demand, aeration equipment, and secondary clarification into one connected AIDIA Excel workflow.