Two identically sized primary settling tanks receive water for Type-I settling (discrete particles in dilute suspension) under laminar flow conditions. The Surface Overflow Rate (SOR) maintained in the two tanks are $30 \mathrm{~m}^{3} / \mathrm{m}^{2}$. d and 15 $\mathrm{m}^{3} / \mathrm{m}^{2}$.d. The lowest diameters of the particles, which shall be settled out completely under SORs of $30 \mathrm{~m}^{3} / \mathrm{m}^{2}$.d and $15 \mathrm{~m}^{3} / \mathrm{m}^{2}$.d are designated as $d_{30}$ and $d_{15},$ respectively. The ratio, $d_{30} / d_{15}$ (round off to two decimal places), is

Two identically sized primary settling tanks receive water for Type-I settling (discrete particles in dilute suspension) under laminar flow conditions. The Surface Overflow Rate (SOR) maintained in the two tanks are $30 \mathrm{~m}^{3} / \mathrm{m}^{2}$. d and 15 $\mathrm{m}^{3} / \mathrm{m}^{2}$.d. The lowest diameters of the particles, which shall be settled out completely under SORs of $30 \mathrm{~m}^{3} / \mathrm{m}^{2}$.d and $15 \mathrm{~m}^{3} / \mathrm{m}^{2}$.d are designated as $d_{30}$ and $d_{15},$ respectively. The ratio, $d_{30} / d_{15}$ (round off to two decimal places), is

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