Consider an aquifer contaminated by entrapped benzene. At a given location, downstream of the benzene entrapment, the dissolved benzene concentration is 11 mg/L. Biodegradation takes place in the...

Consider an aquifer contaminated by entrapped benzene. At a given location, downstream of the benzene entrapment, the dissolved benzene concentration is 11 mg/L. Biodegradation takes place in the aquifer, and it is assumed that 9 mg/L of oxygen is available for utilization by the microorganisms, over a time period of 12 days.

(a) Assuming that 3 mg/L of oxygen is required to biodegrade 1 mg/L of the contaminant, apply the instantaneous reaction expression to provide an estimate of anticipated reduction in benzene concentration due to the presence of 9 mg/L of oxygen.

(b) Repeat the calculation of (a), but apply the Monod kinetic expression, while assuming an oxygen half-saturation constant of 0.1 mg/L, a benzene half saturation constant of 22.6 mg/L, a maximum utilization rate of 9.3/day-mg, and a microorganism population of 0.05 mg/L.

(c) Repeat the calculation of part (a), but apply a first-order decay expression, while assuming a half-life for benzene of 5 days.