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.
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Taxa de aplicação de sólidos (SLR)
O decantador secundário de um sistema de lodos ativados tem uma tarefa dupla: clarificar o efluente (produzir um sobrenadante limpo) e adensar o lodo no fundo para recirculação. Por isso ele precisa ser verificado por dois critérios independentes. O primeiro é a taxa de escoamento superficial (hidráulica), Q/A, ligada à clarificação. O segundo é a taxa de aplicação de sólidos (SLR, solids loading rate), SLR = Q × X ÷ A, que multiplica a vazão pela concentração de sólidos do licor misto (X) e divide pela área — ou seja, a massa de sólidos que chega por m² de decantador por dia, em kg/(m²·dia). Esse critério existe porque, diferente de um decantador primário (água quase limpa), o secundário recebe um licor misto carregado de biomassa que tem de espessar no fundo; se a carga de sólidos exceder a capacidade de adensamento, o manto de lodo sobe e escapa pelo vertedouro, deteriorando o efluente e perdendo biomassa. O dimensionamento correto adota a área que satisfaz simultaneamente o limite hidráulico e o limite de sólidos — geralmente o mais restritivo dos dois governa. Informe a vazão, a concentração de sólidos e a área do decantador.
Related Tools
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.
Spray Volume
Calculate the spray volume applied per hectare, volume = (q × 600) ÷ (L × v), from the total nozzle flow q (L/min), the boom width L (m) and the travel speed v (km/h). The result, in liters per hectare, is the application rate — a critical spraying parameter that must match the pesticide recommendation and the target. The factor 600 converts units. Increasing speed or width lowers the applied volume; increasing nozzle flow raises it. Calibrating correctly ensures the right agrochemical dose, avoiding underdosing (ineffectiveness) or overdosing (waste and phytotoxicity). Enter the nozzle flow, the boom width and the speed.
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.