Example of medium load activated sludge sizing

3 Example of medium load activated sludge sizing 

Cj = saturation in O2 under effective salinity, temperature and pressure conditions. 

Cj( = oxygen content in the purification water, often chosen between 1 and 2 mg-l . 11.25 mg l = saturation in O2 of pure water at 10°C. 

With Cj = 10 and = 1.5, Tj = 0.76 at 15 to 20 C. Disregarding the two other parameters, the corrected amount of oxygen becomes 2 358 kg day b. Correction factor F related to the shape of the aeration tank and to hydraulic conditions. Depending on the type of surface aerator and the shape of the tank, the second F fector 12 = Fi can be calculated (shape of the tank) x F2 (ratio between width and depth) x F3 (specific stirring power) char can be 0.9 for example. A nominal net specific aerator input measured at the shaft of 2 kg kWh of O2 becomes a real input of 1.8. Four aerators, with 20 kW of absorbed power, therefore supply 4 x 20 x 1.8= 144 leg of O2 per hour for a total of 74 that are required on the average. They can be run intermittently and still ensure a maximum stirring power of 37 W m of tank. 

3 Biological treatability of refining an4 steam cracking effluents 

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