It is proposed to decrease the turbidity of a small pond by filtering the very fine sediment that is causing the turbidity (the sediment is sufficiently fine that it has a negligible settling...

It is proposed to decrease the turbidity of a small pond by filtering the very fine sediment that is causing the turbidity (the sediment is sufficiently fine that it has a negligible settling velocity). It is assumed that the pond water is well mixed. The water is to be pumped out, passed through a filter, and returned to the pond. With each pass through the filter, 80% of the sediment is removed. Calculate the times required to reduce the sediment concentration to 25% of the initial value using pumping rates corresponding to retention times of (a) 1 day, (b) 2 days, (c) 5 days, and (d) 10 days.