Oxygen Requirement (Aeration)
Calculate the oxygen requirement of an aerobic treatment system, O₂ = Q × ΔS ÷ 1000 × f, multiplying the flow (m³/day) by the BOD removed (mg/L) and an oxygen-demand factor (typically 1.0–1.5 kg O₂/kg BOD). The result, in kg O₂/day, sizes blowers and aerators in activated sludge and aerated lagoons, ensuring enough oxygen for the biological oxidation of organic matter. Enter the flow, the BOD removed and the oxygenation factor.
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Necessidade de oxigênio (aeração)
Num tratamento aeróbio, as bactérias oxidam a matéria orgânica usando oxigênio — e fornecer esse oxigênio (por sopradores e difusores ou aeradores mecânicos) é geralmente o maior consumo de energia de uma ETE. Estimar quanto O₂ por dia o sistema precisa é, portanto, essencial. A forma simplificada é O₂ = Q × ΔS ÷ 1000 × f: multiplica-se a vazão Q (m³/dia) pela DBO removida ΔS (mg/L, dividida por 1000 para virar kg/m³) para obter a carga de matéria orgânica oxidada por dia, e aplica-se um fator f (kg O₂ por kg DBO, tipicamente 1,0–1,5) que cobre tanto a oxidação do carbono quanto a respiração endógena da biomassa. O resultado, em kg O₂/dia, é o ponto de partida para dimensionar a capacidade dos sopradores, já corrigida depois por fatores de transferência (α, β) e pela altitude/temperatura. Subdimensionar a aeração derruba a eficiência e gera odores; superdimensionar desperdiça energia. Informe a vazão, a DBO removida e o fator de oxigenação.
Related Tools
Sludge Production
Calculate the biological sludge production of a plant, P_x = Y × ΔS ÷ 1000 × Q, multiplying the cell yield coefficient (Y, kg VSS/kg BOD), the BOD removed (mg/L) and the flow (m³/day). The result, in kg/day, estimates the excess sludge mass generated by biomass growth, key to sizing wasting, thickening, dewatering and final disposal — a step that often drives much of a treatment plant's operating cost. Enter the yield Y, the BOD removed and the flow.
Solids Loading Rate (Clarifier)
Calculate the solids loading rate (SLR) of a secondary clarifier, SLR = Q × X ÷ A, multiplying the flow (m³/day) by the mixed-liquor solids concentration (mg/L, converted to kg/m³) and dividing by the surface area (m²). The result, in kg/(m²·day), is a design criterion independent of the surface overflow (hydraulic) rate: an activated-sludge secondary clarifier must satisfy both the hydraulic limit and the solids loading limit, since it receives a concentrated mixed liquor that must thicken at the bottom. Excessive solids loading causes sludge to wash out with the effluent. Enter the flow, the solids concentration and the clarifier area.
Sludge Recycle Ratio
Calculate the sludge recycle ratio (R) of an activated-sludge system by mass balance, R = X ÷ (X_r − X), from the mixed-liquor suspended solids (MLSS) and the return sludge concentration. The result (dimensionless, or ×100%) gives the fraction of influent flow that must be recycled from the secondary clarifier to keep the desired biomass in the reactor. Typical ratios range from 0.25 to 1.0. Enter the reactor MLSS and the return sludge concentration.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.