1.A hi-vol clean filter weighs 18.00 g. After a 24 hour sampling period the filter is removed and weighs 18.65 g. The initial flow rate through the filter was 2.5 m3/min. When the filter was removed the flow rate through the filter was 1 m3/min. What is the concentration of particles in the air?
A) 0.29 ?g/m3
B) 2.90 ?g/m3
C) 29.0 ?g/m3
D) 290 ?/m3
E) 2900 ?g/m3
2.An activated sludge system treats 1500 m3/day of raw wastewater with a BOD of 250 mg/L. The reactor volume is 375 m3. The kinetic parameters were determined to be: ? = 3 day-1, Y = 0.55 kg SS/kg cells, and Ks = 150 mg/L. If the required effluent BOD is 15 mg/L, what is the mixed liquor suspended solids concentration?
A) 2500 mg/L
B) 2000 mg/L
C) 1000 mg/L
D) 500 mg/L
E) 250 mg/L
3.A flow of 125,000 gallons per day enters a sedimentation basin which is 20 feet wide, 60 feet long and 12 feet deep. What is the minimum settling velocity of a particles that will be 100% removed by the basin? (There are 7.48 gallons per cubic foot)
A) 0.05 ft/hr
B) 0.5 ft/hr
C) 5.0 ft/hr
D) 0.5 ft/day
E) 5 ft/day
4.A large power plant emits 1,500 kg SO2 per day into a neutral atmosphere with a wind speed of 4 m/s. A town is located 5 km away from the plant, 5 degrees east of the wind direction. If the effective stack height of the plant is 100 m, and the ground reflects the SO2 emission perfectly what is the SO2 concentration at a sampling point located 2 m above the ground in the town.
A) 1 x 106 ?g/m3
B) 1 x 103 ?g/m3
C) 1 ?g/m3
D) 1 x 10-3 ?g/m3
E) 1 x 10-6 ?g/m3