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Oxygen Transfer Design

Aeration Design

Calculate oxygen transfer, diffuser selection, and blower sizing for wastewater treatment systems.

SOTR/AOTR

Conversion

Diffuser Types

3 Types

Energy Analysis

kWh/kg O2

Cost Estimate

CAPEX/OPEX

Open a shared project · เปิดโครงการร่วม to keep this analysis with its design basis.

Aeration System Design

Design diffuser system, blower sizing, and oxygen transfer calculations.

Quick Power Estimate

Power
7.4 kW
Daily Energy
178 kWh
Specific Energy
0.178 kWh/m³

Design Parameters

Tank Parameters

Oxygen Demand

Conditions

Blower energy duty / ภาระพลังงานเครื่องเป่า

When disabled, energy is an explicit full design-duty scenario. Supply aggregate electrical input for all operating blowers, including stated auxiliaries; do not enter a single motor nameplate. This separate duty does not prove airflow capacity or process adequacy. / ระบุขอบเขตเครื่องที่เดินและอุปกรณ์ร่วม การประเมินนี้ไม่ยืนยันสมรรถนะการเติมอากาศ

Oxygen Transfer Correction Factors

Diffuser Types Comparison

Fine Bubble

SOTE:25-35%
Alpha:0.4-0.8
Applications:

Activated sludge, deep tanks

Pros:

  • High efficiency
  • Low energy
  • Good for deep tanks

Coarse Bubble

SOTE:10-15%
Alpha:0.6-0.9
Applications:

Mixing, equalization, pre-treatment

Pros:

  • Low fouling
  • Simple maintenance
  • Good mixing

Mechanical Surface

SOTE:1.2-2.4 kg O2/kWh
Alpha:0.8-0.95
Applications:

Oxidation ditches, lagoons

Pros:

  • No diffuser fouling
  • Good for shallow basins

Key Design Factors

Alpha (α)

Wastewater correction factor

Typical:0.4-0.8 for domestic wastewater
αSOTE = OTE in wastewater / OTE in clean water

Beta (β)

Salinity correction factor

Typical:0.95-0.99 for domestic wastewater
Cs* = β × Cs (standard)

Theta (θ)

Temperature correction factor

Typical:1.024 standard value
KLa(T) = KLa(20) × θ^(T-20)

Fouling Factor (F)

Diffuser performance decline

Typical:0.65-0.90 over time
Actual SOTE = Design SOTE × F

Key Formulas

Oxygen Requirement

AOR = Q × (So - S) / (1000 × f)
+ 4.57 × Q × (TKNo - TKN) / 1000
- 2.86 × Q × (NOx) / 1000

SOTR from AOTR

SOTR = AOTR × (Cs,20 / (β × Cs,T - CL))
× (1 / α) × (1 / θ^(T-20))

Size aeration systems: convert standard oxygen transfer (SOTR) to actual field conditions (AOTR), select fine/coarse-bubble diffusers, size blowers with redundancy, and estimate energy cost.

ออกแบบระบบเติมอากาศ: แปลงค่าการถ่ายเทออกซิเจนมาตรฐาน (SOTR) เป็นสภาวะจริง (AOTR), เลือก diffuser แบบฟองละเอียด/หยาบ, เลือกขนาด blower พร้อมสำรอง และประเมินต้นทุนพลังงาน

When to use

  • Determining oxygen demand and blower capacity for an aeration basin
  • Comparing fine- vs coarse-bubble diffuser efficiency and energy
  • Sizing standby blowers for reliability

How to use

  1. 1Enter oxygen demand, basin depth, temperature and elevation.
  2. 2Choose diffuser type and α, β, F (fouling) factors.
  3. 3Read required SOTR, air flow, blower power and energy cost.

Key formulas

Field to standard transfer

AOTR = SOTR · [(β·C_s,T,H − C_L)/C_s,20] · 1.024^(T−20) · α · F

α = transfer factor; β = salinity/surface factor; F = fouling

Blower adiabatic power

P_w = (w·R·T₁)/(k₁·e) · [(p₂/p₁)^k₁ − 1]

k₁ = (k−1)/k, k≈1.395 for air; e = efficiency

AOTR derate

SOTR
100 kg O₂/h
α, β, F
0.50, 0.95, 0.90
T, C_L
28 °C, 2.0 mg/L

AOTR ≈ 100 · (0.95·7.8 − 2.0)/9.08 · 1.024^8 · 0.50 · 0.90 ≈ 26 kg O₂/h

References

  • • Metcalf & Eddy (2014), Wastewater Engineering, 5th ed., Ch. 5
  • • ASCE/EWRI 2-06 — Standard Guidelines for In-Process Oxygen Transfer Testing

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