Question

A company is using an outdoor pond to get rid of some organic material in a 500 gallons/ hour wastewater stream. In the current situation, the pond which has a surface area of 1.00 acre (= 43,560 ft^2) and the average depth of 6 ft, removes of 62% of the organic material, but the company is not satisfied with this rate of removal and plans on digging a second pond to provide additional treatment of the effluent so that a total of 95% of the organics are removed from the wastewater. The company’s data indicates that, being outdoors the existing pond is subject to evaporation at the rate of 25 gallons/hour. For geographical reasons, the additional pond cannot be dug deeper than the existing pond and must therefore have a depth of no more than 6 ft. (a) Estimate the decay coefficient of the organics in the existing pond. (b) Determine the area (in acres) that the planned needs to have to enable the company to achieve its goal of 95% removal of the organics. For this assume that the second pond is place in series from the first (that is, the effluent of the first pond feeds the second pond), that the decay constant will be the same in the second pond as it presently is in the first pond, and that water loss by evaporation is proportional to the surface area of the pond.

Answer 1

thank you.