(2 points) a perfectly mixed aeration pond with no recycle serves as the biological reactor for a small community. the pond receives 30 m3 /d of influent with a bod of 350 mg/l that must be reduced to 20 mg/l before discharge. it has been found that the kinetic constants for this system are: ks = 100 mg bod/l, kd = 0.10 day-1 , μm = 1.6 day-1 , y = 0.60 mg ss/mg bod. assume xo = 0. a. what must the hydraulic retention time (θ = v/q) be in the aeration pond? b. what mass of microbes will be produced in the pond each day?