Consider the design of an engineered wetland amended with limestone to treat acidic drainage from a coal mine. For the purposes of this problem, we will focus on the total dissolved solids (TDS) of the flow which is 750 mg/L. The TDS is removed in the wetland following a first-order process with k = 0.1 day^-1. Determine the required volume for the wetland needed to reduce the influent TDS to 250 mg/L in the effluent, assuming it operates under steady-state conditions and that the flow from the mine equals 50 gallons/min.