Surface Overflow Rate (SOR) of a primary settling tank (discrete settling) is 20000 litre $/ \mathrm{m}^{2}$ per day. Kinematic viscosity of water in the tank is $1.01 \times 10^{-2} \mathrm{~cm}^{2} / \mathrm{s}$. Specific gravity of the settling particles is 2.64. Acceleration due to gravity is $9.81 \mathrm{~m} / \mathrm{s}^{2}$. The minimum diameter (in $\mu \mathrm{m},$ round off to one decimal place ) of the particles that will be removed with $80 \%$ efficiency in the tank, is

Surface Overflow Rate (SOR) of a primary settling tank (discrete settling) is 20000 litre $/ \mathrm{m}^{2}$ per day. Kinematic viscosity of water in the tank is $1.01 \times 10^{-2} \mathrm{~cm}^{2} / \mathrm{s}$. Specific gravity of the settling particles is 2.64. Acceleration due to gravity is $9.81 \mathrm{~m} / \mathrm{s}^{2}$. The minimum diameter (in $\mu \mathrm{m},$ round off to one decimal place ) of the particles that will be removed with $80 \%$ efficiency in the tank, is

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