Your firm has been asked to do a preliminary study of the feasibility of a new A /O™ BPR wastewater treatment plant for Pittsburgh. Begin the design of the complete-mix BOD removal and nitrification...

Your firm has been asked to do a preliminary study of the feasibility of a new A /O™ BPR wastewater treatment plant for Pittsburgh. Begin the design of the complete-mix BOD removal and nitrification stage. As a first step determine the SRT and volume of tank required for nitrification using the following design data:

Influent data after primary settling

Design flow rate = 35,500 m³
/d

BOD = 200 mg/L

bCOD = 320 mg/L

rbCOD = 60 mg/L

Total Kjeldahl nitrogen (TKN) = 45 mg/L

NH -N = 35 mg/L

Soluble phosphorus = 7 g/m³

Total suspended solids (TSS) = 75 mg/L

Volatile suspended solids (VSS) = 65 mg/L

Biodegradable volatile suspended solids = 40 mg/L

Minimum sustained temperature = 15°C

pH = 7.0

Alkalinity = 220 mg/L as CaCO

Effluent discharge standards

bCOD ≤ 20 mg/L

 NH₃
-N ≤ 1.0 mg/L

NO₃
-N ≤ 10 mg/L

TSS ≤ 10 mg/L

Total phosphorus ≤ 2.0 mg/L

Assume DO for aeration tank nitrification = 2.0 mg/L; MLSS = 3,500 mg/L, MLVSS = (0.8) MLSS, NO = 80% of TKN, and RAS = 0.54(Q).