(Solved): 6. It is proposed to construct a facultative pond treating \( 600 \mathrm{~m}^{3} / \mathrm{d} \) w ...

6. It is proposed to construct a facultative pond treating \( 600 \mathrm{~m}^{3} / \mathrm{d} \) wastewater with a \( B O D \) of \( 300 \mathrm{mg} / \mathrm{L} \) to \( 50 \mathrm{mg} / \mathrm{L} \). The reaction constant \( \mathrm{k} \) at \( 20^{\circ} \mathrm{C}=0.30 \mathrm{~d}^{-1} \). Compute the required surface area of the facultative pond and the effluent BOD if the temperature of the coldest month is \( 13^{\circ} \mathrm{C} . \mathrm{kT}_{T}=\mathrm{k}_{20}(1.05)^{(\mathrm{t}-20)} \). Design the facultative pond and check if it meets the surface loading, \( \lambda_{\mathrm{s}}=L, Q / A=60(1.099)^{\mathrm{T}} \) in \( \mathrm{Kg} / \mathrm{ha} / \mathrm{d} \) ( 8 marks)