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In: Civil Engineering

The Lolla Hart hospital has a small activated sludge plant to treat its wastewater. The average...

The Lolla Hart hospital has a small activated sludge plant to treat its wastewater. The average daily hospital discharge is 1,500 L per day per bed, and the average soluble BOD5 after primary settling is 500 mg/L. Their permit dictates that the effluent BOD5 and TSS cannot exceed 30 and 20 mg/L, respectively, on an annual basis. Assume the MLVSS concentration in the aeration basin will be maintained at 3,000 mg/L. Also, assume that the concentration of BOD5 of the suspended solids is equal to 60% of the suspended solids concentration. The biokinetic coefficients were measured and determined to be:

Ks=70 mg/L BOD5

um=2.5 day-1

kd = 0.06 day-1

Y = 0.6 mg VSS/mg BOD5 removed

Find:

SRT in days

The Aeration basin volume (L)

The Aeration period (days)

The kg of secondary solids wasted each day

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