Ariver has a flow velocity of 3 cm/s, an aeration coefficient of 0.5 d–1, and a temperature of 20°c. after initial mixing with wastewater, the river has a do concentration of 8.0 mg/l, an ultimate bod of 25 mg/l, and a bod decay constant of 0.8 d–1. neglecting the effect of sedimentation on bod removal, determine the distance over which the do is less than or equal to 7 mg/l.

An open feedwater heater operates at steady state with liquid entering at inlet 1 with t? = 40°c and pl = 1 .2 mpa. water vapor att2-200°c and p2 = 1.2 mpa enters at inlet 2. saturated liquid water exits with a pressure of pa 1.2 mpa. neglect heat transfer with the surroundings and all kinetic and potential energy effects, determine the mass flow rate of steam at inlet 2 if the mass flow rate of liquid water at inlet 1 is given as 2 kg/s.