(Solved): 16.10 A site with groundwater contaminated with benzo[a]pyrene has been evaluated for in situ biorem ...

16.10 A site with groundwater contaminated with benzo[a]pyrene has been evaluated for in situ bioremediation. The mass of benzo[a]pyrene in the system is 64 kg , and it must be treated to 0.1 kg . Bioremediation is controlled by benzo[a]pyrene desorption; the rate constant for contaminant desorption is 0.017 day \( ^{-1} \). The site has 24 permanent wells on 3 m centers, which provide sufficient dissolved oxygen throughout the site. Two oxygen sources have been evaluated in benchscale treatability tests. The first option for an oxygen source is a fabric sock filled with magnesium peroxide. The magnesium peroxide lifetime is 60 days, and it costs \( \$ 44 \) to replace. The second option for an oxygen source is pumping air into each of 24 wells. The cost of the air pump, piping, and diffusers is \( \$ 8500 \). The operation cost for the pump is 3.8 \( \mathrm{kW} \cdot \mathrm{h} \) and electricity costs \( \$ 0.11 / \mathrm{kW} \cdot \mathrm{h} \). Determine the cost of each system and select the least-cost option.