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.
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Relação de recirculação de lodo
Num sistema de lodos ativados, o lodo que sedimenta no decantador secundário é recirculado de volta ao reator para manter lá dentro uma concentração de biomassa alta e estável. A relação de recirculação (R) diz qual fração da vazão afluente precisa retornar para isso, e sai de um balanço de massa de sólidos no reator: R = X ÷ (X_r − X), onde X é a concentração de sólidos no licor misto (SSLM) que se quer manter e X_r é a concentração do lodo adensado que retorna do fundo do decantador. Como o lodo de retorno é mais concentrado que o licor misto, R fica tipicamente entre 0,25 e 1,0 (25% a 100% da vazão). Quanto melhor o lodo adensa no decantador (X_r alto), menor a recirculação necessária. Se a sedimentação piora e X_r cai, é preciso recircular mais para não perder biomassa. A recirculação é, portanto, o elo que acopla o reator biológico ao decantador e mantém o sistema em regime. Informe a SSLM do reator e a concentração do lodo de retorno.
Related Tools
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.
Concentration Ratio
Compute the concentration ratio of a processing operation, CR = feed mass / concentrate mass, how many tonnes of raw ore are needed to produce one tonne of concentrate. It measures the degree of upgrade: high ratios indicate lean ores that require heavy processing. It is useful in the mass balance and plant sizing. Enter the feed mass and the concentrate mass.
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.
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.