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Engineering Tool · Wastewater Treatment

Activated Sludge Designer

Design conventional activated-sludge carbon removal, with optional nitrification, using one traceable biological calculation core.

Status
Development candidate
Modes
Carbon removal · Carbon removal + nitrification
Units
Metric / US customary
LOCAL DESIGN · 0.1.0-wave02a
BIOLOGICAL PROCESS MODE

Conventional activated sludge

Carbon removal is the baseline. Nitrification adds an explicit AOB SRT and nitrogen balance.

DESIGN INPUTS

Process basis

01 / 02
01

Project / design basis

02

Influent / effluent basis

BOD5 and COD remain separate measured bases.

The entered BOD5 influent and target values are the selected biological design basis. The model does not predict downstream clarification-related particulate BOD5 effects.

03

Solids / operating basis

SRT is reported on a total MLVSS inventory and loss basis.

Carbon-removal mode requires a user-selected SRT. No universal minimum carbon-removal SRT is applied.

Advanced assumptions & solids boundariesProject editable

SCREENING / PROJECT ASSUMPTION — these starting values are not universal constants or EPA defaults. Replace them with site measurements or calibrated project values.

CURRENT RESULT

Engineering decision

VALID
Selected SRT10d
Reactor volume3,514.286m³
HRT8.434h
MLSS3,500mg/L as TSS
MLVSS2,845.528mg/L as VSS
Applied F/M0.21kg BOD5/(kg MLVSS·d)
WAS solids loss1,131.414kg TSS/d
Average biological AOR1,864kg O₂/d
Mass closurePASS
Process RAS boundaryContinuity only
Effluent TSS roleImposed design boundary

Calculation boundaries

Secondary clarificationEffluent TSS is imposed; settling and capacity are not predicted.
Oxygen systemBiological AOR only; transfer and blower duty are outside this calculation.
Peak oxygen demandUnavailable until an explicit peak case is provided.
RESULT PACKAGE

Report this process state

PDF preview, print, and download use the same generated PDF. Any input edit invalidates the report snapshot.

Core authority@atlas/biological-process-core · 0.1.0-wave02a37e4f57c142d38f51026d5246225d30e4b5232398c034b54d0d9910ba8617345
DETAILED ENGINEERING RESULTS

Biological process balance

CARBON REMOVAL

Project / design basis

ParameterResultBasis / source
Project / caseMunicipal carbon removal referenceNamed design caseUser input
Process modeCarbon removalConventional activated sludgeUser-selected mode
Flow10,000 m³/dAVERAGE_DAYUser input
Temperature20 °CBiological process temperatureUser input

Influent / effluent basis

ParameterResultBasis / source
Biological substrate basis policyBOD5 — user-selected biological design basisSelected substrate basis: BOD5The entered BOD5 influent and target values are the selected biological design basis. The model does not predict downstream clarification-related particulate BOD5 effects.
Influent BOD5210 mg/L as BOD5 (O₂)Selected substrate basis; no BOD/COD conversionUSER_CONFIGURED
Effluent target BOD510 mg/L as BOD5 (O₂)Selected substrate basis; no BOD/COD conversionUser target
Applied BOD5 load2,100 kg BOD5/dQ × influent concentration@atlas/biological-process-core
Removed BOD5 load2,000 kg BOD5/dQ × (influent − effluent target)@atlas/biological-process-core

Biomass / solids inventory

ParameterResultBasis / source
Gross heterotroph synthesis1,200 kg VSS/dGross BOD5-removed yield basisSCREEN_HET_Y_BOD5
Heterotroph decay rate at design temperature0.05 d⁻¹bH(T)=bH,20 × θ^(T−20°C)SCREEN_HET_DECAY_20
Heterotroph decay loss400 kg VSS/dGross synthesis − net active heterotroph production@atlas/biological-process-core
Net active heterotroph production800 kg VSS/dActive heterotroph VSS; excludes inert solids@atlas/biological-process-core
Active autotroph productionNot available kg VSS/dActive AOB VSS net of decayNot applicable
Influent inert VSS200 kg VSS/dExternally characterized inert influent VSSUser/project assumption
Endogenous residue0 kg VSS/dEnabled residue fraction of heterotroph decaySCREEN_ENDOGENOUS_RESIDUE_FRACTION
Fixed / inorganic solids230 kg TSS/dNonvolatile TSS loadUser/project assumption
External chemical solids0 kg TSS/dExternal supplied TSS; no reagent sizingUser input
Total VSS production1,000 kg VSS/dActive biomass + inert influent + endogenous residue@atlas/biological-process-core
Total TSS production1,230 kg TSS/dVSS production + fixed and externally supplied chemical TSS@atlas/biological-process-core
Total MLVSS inventory10,000 kg VSSTotal MLVSS inventory at selected SRT@atlas/biological-process-core
Total MLSS inventory12,300 kg TSSMLSS concentration × aeration-tank volume@atlas/biological-process-core
VSS/TSS production fraction0.813 kg VSS/kg TSSProduction basis; does not imply all VSS is active biomass@atlas/biological-process-core

Solids retention

ParameterResultBasis / source
Achieved MLVSS SRT10 dMLVSS inventory / external MLVSS WAS and effluent losses@atlas/biological-process-core
Removed-basis F/M0.2 kg BOD5/(kg MLVSS·d)Removed BOD5 load / MLVSS inventory; applied-basis F/M remains primary@atlas/biological-process-core

RAS / WAS continuity

ParameterResultBasis / source
Required WAS flow141.427 m³/dExternal WAS flowDerived from WAS TSS and imposed effluent TSS boundary
WAS solids loss1,131.414 kg TSS/dExternal WAS TSS mass loss@atlas/biological-process-core
Effluent TSS loss98.586 kg TSS/dExternal loss from imposed effluent TSS design boundaryNot a clarifier prediction
Process RAS requirement7,504.444 m³/dInternal recycle; not net solids generation/removalAlgebraic process-continuity assumption only
RAS / influent flow ratio0.75 m³/m³Process continuity onlyNo settling capacity or clarifier performance prediction

Nitrogen balance

ParameterResultBasis / source
Influent NH4-NNot available kg N/dAmmonium expressed as NUser input
NH4-N oxidizedNot available kg N/dNH4-N oxidized after explicit biomass assimilation@atlas/biological-process-core
Heterotroph N assimilationNot available kg N/dBiomass N content × active heterotroph VSS@atlas/biological-process-core
Autotroph N assimilationNot available kg N/dBiomass N content × active autotroph VSS@atlas/biological-process-core
Unmodeled organic nitrogen contextNot available kg N/dTKN − NH4-N; no mineralization modeledReported context only; not included as NH4-N oxidized
NH4-N balance residualNot available kg N/dNH4-N available − heterotroph assimilation − autotroph assimilation − oxidation@atlas/biological-process-core

Alkalinity balance

ParameterResultBasis / source
Influent alkalinityNot available mg/L as CaCO₃Influent alkalinityNot applicable
Nitrification consumptionNot available kg CaCO₃/d7.14 kg CaCO3/kg NH4-N oxidizedUS EPA Nutrient Control Design Manual
Denitrification recoveryNot available kg CaCO₃/d3.57 kg CaCO3/kg NO3-N reduced; actual adapter-supplied reduction onlyNot used by conventional product
Residual alkalinityNot available mg/L as CaCO₃Influent − nitrification consumption + actual adapter recoveryNo chemical dose is sized by this tool

Biological oxygen requirement

ParameterResultBasis / source
Carbonaceous AOR1,864 kg O₂/dRemoved BOD5 × entered BODu/BOD5 1.5 minus 1.42 kg O2/kg net active heterotroph VSS synthesis.Biological demand before oxygen transfer
Nitrification AOR0 kg O₂/d4.57 kg O2/kg NH4-N oxidized to nitrateUS EPA Nutrient Control Design Manual
Denitrification oxygen credit0 kg O₂/d2.86 kg O2/kg actual NO3-N reducedAdapter-only; zero for Activated Sludge Designer
Average total AOR1,864 kg O₂/dCarbonaceous + nitrification − actual denitrification creditBiological AOR; not oxygen-transfer/blower duty
Peak AORNot available kg O₂/dNo peak scenario or documented peak basis suppliedPeak is null; no generic peak factor

Mass closure

ParameterResultBasis / source
Authoritative closure statePASSGenerated TSS = WAS external loss + secondary effluent TSS loss; RAS cancels internally@atlas/biological-process-core
Generated TSS1,230 kg TSS/dExternal solids generated@atlas/biological-process-core
WAS external loss1,131.414 kg TSS/dExternal loss@atlas/biological-process-core
Effluent external loss98.586 kg TSS/dExternal loss at imposed TSS boundary@atlas/biological-process-core
Closure residual0 kg TSS/dGeneration − WAS loss − effluent lossTolerance 0 kg/d; RAS net generation is zero

Coefficient registry & provenance

CoefficientValueAuthority / source / policy
Flow/concentration mass-load divisorFLOW_CONCENTRATION_LOAD_DIVISOR1,000 L/m³ and mg/gREFERENCE_SUPPORTEDQ[m³/d]×C[mg/L]/1000 = kg/dSI dimensional conversion.Steady-state volumetric flow and mass concentration.Fixed dimensional conversion.
Heterotroph gross yield on BOD5 removedSCREEN_HET_Y_BOD50.6 kg VSS/kg BOD5 removedSCREENING_ASSUMPTIONGross synthesis before decay; BOD5 basisWave 02A independent benchmark project assumption. It is not an EPA default.Editable initial value for preliminary steady-state screening only.Visible, editable screening assumption; site/project calibration required.
Heterotroph endogenous decay at 20°CSCREEN_HET_DECAY_200.05 d⁻¹SCREENING_ASSUMPTIONSpecific heterotroph decay rateWave 02A independent benchmark project assumption. It is not an EPA default.Temperature-corrected with the separately declared project θ.Visible and editable.
Heterotroph decay temperature coefficientSCREEN_HET_THETA_DECAY1.04 dimensionlessSCREENING_ASSUMPTIONbH(T)=bH,20×θ^(T−20°C)Screening assumption; no universal value established in Gate 02.Project temperature correction for heterotroph decay only.Visible and editable; not shared with AOB kinetics.
Biomass nitrogen contentSCREEN_BIOMASS_N0.08 kg N/kg active VSSSCREENING_ASSUMPTIONNitrogen assimilation for heterotroph and autotroph net productionWave 02A independent benchmark project assumption; not a universal plant constant.Explicit ammonia assimilation term in the steady-state N balance.Visible and editable.
Endogenous residue fraction of decaySCREEN_ENDOGENOUS_RESIDUE_FRACTION0 dimensionlessSCREENING_ASSUMPTIONExplicit residue yield from decay lossDisabled in the independent reference case; no universal fraction established.Zero disables residue production; nonzero values are separately reported as inert/endogenous VSS.Visible project input; default is disabled, not a biological law.
Influent inert VSS loadSCREEN_INFLUENT_INERT_VSS200 kg VSS/dSCREENING_ASSUMPTIONExternally supplied influent inert solids massWave 02A independent benchmark project assumption.Added to VSS production and inventory separately from active biomass.Visible and editable; replace with influent characterization.
Influent fixed/inorganic TSS loadSCREEN_FIXED_TSS230 kg TSS/dSCREENING_ASSUMPTIONExternally supplied fixed solids loadWave 02A independent benchmark project assumption.Added to TSS production only; not active or volatile biomass.Visible and editable; replace with influent characterization.
Externally supplied chemical TSSSCREEN_EXTERNAL_CHEMICAL_TSS0 kg TSS/dSCREENING_ASSUMPTIONChemical solids supplied by a separate process calculationNo chemical solids are included in the Wave 02A benchmark.External input only; this core does not size or select chemical reagents.Visible project input; default zero means none supplied.
WAS TSS concentrationSCREEN_WAS_TSS8,000 mg/L as TSSSCREENING_ASSUMPTIONProcess-continuity assumption onlyWave 02A independent benchmark project assumption; not a clarifier capacity prediction.Used to derive WAS flow from required external WAS solids loss.Visible and editable.
RAS/underflow TSS concentrationSCREEN_RAS_TSS8,000 mg/L as TSSSCREENING_ASSUMPTIONProcess-continuity assumption onlyWave 02A independent benchmark project assumption; not a clarifier capacity prediction.Algebraic RAS continuity balance; no settling/flux inference.Visible and editable.
Imposed effluent TSS boundarySCREEN_EFFLUENT_TSS10 mg/L as TSSSCREENING_ASSUMPTIONIMPOSED_DESIGN_BOUNDARYWave 02A independent benchmark project assumption; not predicted by this product.External solids mass closure only; not a secondary clarifier prediction.Visible and editable.
Project RAS/plant-flow operational screenSCREEN_MAX_RAS_RATIO1.2 m³/m³SCREENING_ASSUMPTIONContinuity operating limit; not a hydraulic/clarifier capacity ratingScreening assumption only.If required RAS exceeds this value, return CAPACITY_CONFLICT; never cap a required result.Visible and editable; optional.
Ultimate BOD to BOD5 ratioSCREEN_BODU_BOD51.5 kg BODu/kg BOD5SCREENING_ASSUMPTIONCarbonaceous AOR oxygen-equivalent inputWave 02A independent benchmark project assumption. Not universal.Used only for BOD5-basis carbonaceous AOR when entered; not used to convert BOD5 to COD.Visible and editable; use measured/site-specific ultimate BOD where available.
Biomass synthesis oxygen equivalentBIOLOGICAL_OXYGEN_BIOMASS_EQUIVALENT1.42 kg O2/kg VSSREFERENCE_SUPPORTEDEmpirical-cell oxygen equivalent 160/113US EPA, Biological Concepts for Design and Operation of the Activated Sludge Process, empirical biomass formula C5H7NO2 and oxygen equivalent 160/113.Applied only as the explicitly named net active heterotroph biomass credit in the Wave 02A AOR basis.Fixed empirical conversion; changing the biomass-credit method requires a new model revision.

Warnings / limitations

  • No calculation warningsReview the declared model assumptions and references before design adoption.
  • Clarifier boundaryEffluent TSS is imposed as a design boundary. FluxMatrix owns settling, blanket, geometry and capacity behavior.
  • Oxygen boundaryThis is biological AOR only. OxyMatrix owns future oxygen-transfer and blower calculations and must consume accepted AOR without recalculating biology.
  • Alkalinity boundaryThe core reports residual biological alkalinity. NutriMatrix owns purchased alkalinity reagent selection, feed and cost.
01

Engineering Basis

Methodology

Deterministic steady-state process calculation on an explicit BOD5 or COD basis. Heterotroph synthesis and decay remain separate from inert and fixed solids.

The selected BOD5 or COD values are the biological design substrate basis. COD is used as entered without automatic fractionation into biodegradable, soluble, inert, or particulate non-biodegradable COD; provide an appropriate project/site biological COD basis or explicitly accept the un-fractionated screening assumption. For BOD5, the model does not predict downstream clarification-related particulate BOD5 effects.

Selected SRT is defined on total MLVSS inventory divided by external MLVSS loss. Carbon-removal mode requires a user-selected SRT; nitrification mode screens minimum SRT from temperature, effluent NH4-N, DO, AOB growth and decay.

F/M is applied substrate load divided by aeration-tank MLVSS inventory. Biological AOR is calculated before oxygen transfer and blower requirements.

Standards / Reference Basis

US EPA Nutrient Control Design Manual (2010), Table 4-4 and nitrification equationsUS EPA Process Control Manual: Aerobic Biological Wastewater Treatment Facilities, Section II F/M exampleUS EPA Biological Concepts for Design and Operation of the Activated Sludge Process, empirical biomass oxygen equivalent

Assumptions

  • Heterotroph yield, decay, temperature correction, BODu/BOD5, biomass nitrogen content and solids composition are visible project or screening assumptions, not universal EPA defaults.
  • The EPA-based AOB coefficient set is a reference set only; project/site calibrated overrides remain available and carry their source note.
  • Secondary-effluent TSS is an imposed design boundary unless a later clarifier model supplies a prediction.

Scope / Limitations

  • Preliminary steady-state activated-sludge process calculation; no dynamic, toxicity, alkalinity reagent-dose, denitrification, EBPR or chemical phosphorus model.
  • Process RAS continuity is an algebraic solids-balance requirement. It does not predict settling flux, blanket behavior, clarifier geometry capacity or effluent TSS.
  • Biological AOR is not oxygen-transfer performance, diffuser airflow or blower sizing. OxyMatrix remains the oxygen-transfer authority.
02

Engineering Path

Conventional activated-sludge branch

  • Primary wastewater clarification
  • Activated Sludge Designer
  • OxyMatrix Consumes an accepted biological AOR for future linked operation; no automatic transfer is active.
  • Secondary solids separation — FluxMatrix Clarifier settling and capacity are reviewed separately from process RAS continuity.

Alternative nutrient-removal branch

  • BNRMatrix Alternative biological process for nutrient-removal configurations; not a required step after this designer.
03

Related Resources

Tools