Calculate nitrogen and phosphorus removal requirements, anoxic reactor volume, oxygen demand, and chemical precipitation doses for biological nutrient removal (BNR) processes.
Enter your process parameters below to calculate design values. All calculations follow industry-standard methodologies.
BNR processes combine nitrification-denitrification for nitrogen removal and enhanced biological phosphorus removal (EBPR) for phosphorus control. The A²O process uses anaerobic, anoxic, and oxic zones in sequence. The Modified Ludzack-Ettinger (MLE) process provides pre-denitrification. The 4-stage Bardenpho process achieves very low effluent nitrogen. SBR and MBBR configurations can also achieve BNR with appropriate cycle timing or zone sequencing.
Chemical precipitation is often used alongside biological P removal or as the sole P removal method. Ferric chloride (FeCl₃) precipitates as FePO₄ at a molar ratio of ~1.8:1. Aluminium sulphate (alum) precipitates as AlPO₄ at ~1.5:1. Polyaluminium chloride (PAC) is more efficient at ~1.2:1. Lime produces Ca₁₀(PO₄)₆(OH)₂ at ~3:1 but generates more sludge. Chemical P removal can achieve < 0.5 mg/L TP regardless of influent variability.
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