The sludge from the aeration tank of the Activated Sludge Process ASP has solids content by weight 2What is the density of the sludge removed from the aeration tank-

Sludge from Aeration tank has solid content =2 Solid content =W_solidW_sludge specific gravity of solid G_S=2.2 ρ_w=1000 kg/m^3 Density of sludge =Weight o ...

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Standard IX

Biology

Solid Waste and Different Sources

The sludge fr...

Question

The sludge from the aeration tank of the Activated Sludge Process (ASP) has solids content (by weight) 2%. This sludge is put in a sludge thickener, where sludge volume is reduced to half. Assume that amount of solids in the supernatant from the thicker is negligible, the specific gravity of sludge solid is 2.2 and the density of water is $1000 k g / m^{3}$ .

What is the density of the sludge removed from the aeration tank?

990 k g / m^{3}

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1000 k g / m^{3}

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1011 k g / m^{3}

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1022 k g / m^{3}

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Solution

The correct option is C $1011 k g / m^{3}$
Sludge from Aeration tank has solid content $= 2$ % (by weight)

Solid content $= \frac{W_{s o l i d}}{W_{s l u d g e}}$
specific gravity of solid

$G_{S} = 2.2$

$ρ_{w} = 1000 k g / m^{3}$

Density of sludge
$= \frac{W e i g h t o f s l u d g e}{V o l u m e o f s l u d g e}$

$= \frac{W}{\frac{W_{s}}{G_{s} ρ_{W}} + \frac{W_{W}}{ρ_{W}}}$

$= \frac{W}{\frac{0.02 W}{2.2 \times 1000} + \frac{0.98 W}{1000}}$

$= 1011.029 k g / m^{3}$

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The correct option is C 1011kg/m3Sludge from Aeration tank has solid content =2% (by weight) Solid content =WsolidWsludge specific gravity of solid GS=2.2 ρw=1000kg/m3 Density of sludge =Weight of sludgeVolume of sludge =WWsGsρW+WWρW =W0.02W2.2×1000+0.98W1000 =1011.029kg/m3