Question

1. Some pond water contains 20.O mg/L of some algae, which can be represented by the chemical formula CsHisO&N. Using the following reactions: CoHisO&N606CO2 6H2ONHa NHs 202 NOs H2O (a) Find the theoretical carbonaceous oxygen demand CBOD (b) Find the nitrogenous oxygen demand NBOD (c) Find the total theoretical biochemical oxygen demand BOD 2. A sandy soil has a hydraulic conductivity of 6.1 x104 m/d, a hydraulic gradient of 0.00141, and porosity of 20%. (a)what is the Darcy velocity (b)what is the average linear velocity of groundwater in the he groundwater, how long (in years) will it take it to reach a monitoring well located 800 m from the pumped well. lgnore retardation effect. aquifer (c)If a contaminant is travelling with 3. A wastewater treatment plant serving a community of 500,000 residents discharges 4.0 m3/s of treated effluent having an ultimate BOD of 50 mg/ into a stream that flows at 10 m/s with a BOD of its own equal to 10 mg/1. The deoxygenation constant, kd is 0.20/day. Assume complete and instantaneous mixing. (a) Estimate the ultimate BOD of the river just downstream from the outfal (b) If the stream has a constant cross section, so that it flows at a constant speed of 0.30m/s, estimate the BOD remaining in the stream at a distance 50,000 m downstream 4. Some wastewater has a BODS of 210 mg/L and an ultimate BOD of 380 mg/L. Find the five-day BOD at 25°C.

Answer 1

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