1.A sample of dry sand having a unit weight of 105 pcf and a specific gravity of 2.70 is placed outdoors. During a storm, the sample degree of saturation increased to 40% while its total volume did not change. Determine the total unit weight and water content of the sample after being wet.
2.Given the following BOD test results..
Initial DO = 8 mg?L
Final DO = 0 mg?l
Dilution = 1/10
what can you say about
a. BOD5
b. BOD ultimate
c. COD
3.a settling tank has a dimension of 3m deep, 10 m long, and 4 mwide. The flow entering the tank is 10 cubic meters perminute.
a. what is the residence time in this tank
b. what is the velocity of a critical particle in thissettleing tank