1.Method One: Calculate According To The Air-Water Ratio
2.Method Two: Calculated by removing 1 kg of BOD and 1.5 kg of O2
3.Methoa Three: Calculate the aeration intensity accordina to the unit tank area
4.Method 4: Calculate according to the number of aeration heads
Known to:
(1) Water flow: 46m3/h
(2) COD: 1200mg/L
(3) No data for BOD,here we assume BOD=0.5*COD=600mg/L
Four Calculate Methods
Method 1
Calculate According To The Air-Water Ratio
Contact oxidation Tank 15:1,so the air volume is: 15*46=690m3/h
Activated sludge tank is 10:1, then the air volume is: 10*46=460 m3/h
The adjustment tank is 5:1, then the air volume is: 5*46=230 m3/h
The total air volume is: 690+460+230=1380 m3/h=23 m3/min
Method 2
Calculated by removing 1 kg of BOD and 1.5 kg of O2
The removal amount of BOD per hour is 0.6kg/m3*1100m3/d÷24=27.5kgBOD/h
Oxygen demand: 27.5*1.5=41.25kgO2
The weight of oxygen in the air is 0.233kg O2/kg air,
Then the required air volume is: 41.25 kgO2÷0.233 O2/kg air=177.04 kg of air
The density of air is 1.293 kg/m3
Then the air volume is: 177.04kg÷1.293 kg/m3=136.92 m3
The oxygen utilization rate of the microporous aeration head is 20%,
Then the actual air demand is: 136.92 m3÷0.2=684.6m3=11.41m3/min
Method 3
Calculate the aeration intensity according to the unit tank area
The aeration intensity is generally 10-20 m3/m2h, taking the middle value, the aeration intensity is 15 m3/m2h
The total area of the contact oxidation tank and activated sludge tank is: 125.4 m2
Then the air volume is: 125.4*15=1881 m3/h=31.35 m3/min
The aeration intensity of the regulating tank is 3m3/m2h, and the area is 120m2, the air volume is 3*120=360m3/h=6m3/min
A total of 37.35 m3/min is required
Method 4
Calculate according to the number of aeration heads
Calculate the pool capacity according to the residence time, and then calculate that a total of 350 aeration heads are required, and the air demand is 3 m3/h.
Then the total required air is 350×3=1050 m3/h=17.5 m3/min
In addition, the gas demand of the regulating tank is 6 m3/min,
Total required air: 23.5 m3/min