WorksheetsSludge treatment
Total questions: 15
Worksheet time: 34mins
The SVI is the volume of the mixed liquor suspended solids divided by the density
of the mixed liquor suspended solids.
True
False
Calculate the SVI for an activated sludge sample given the following: 30-minute settleable solids volume = 150 mL, MLSS = 3,000 mg/L
50
0.5
100
20
The usual duration in conducting SVI
15 minutes
30 minutes
45 minutes
1 hour
Sludge age is used to maintain the proper amount of activated sludge in
the aeration tanks.
True
False
An aeration tank has 16,100 lb of mixed liquor suspended solids. If 2630 lb/day suspended solids enter the aeration tank in the primary effluent flow, what is the sludge age in the aeration tank?
612 days
6.12 days
7 days
None of the followings
An aeration tank contains 480,000 gal of wastewater with a MLSS concentration of 2720 mg/L. If the primary effluent flow is 2.9 MGD with a suspended solids concentration of 110 mg/L, what is the sludge age?
4.1 days
4.2 days
4.3 days
4.4 days
An aeration tank is 110 ft long by 50 ft wide and operates at a depth of 14 ft. The MLSS concentration in the aeration tank is 2510 mg/L. If the influent flow to the tank is 2.88 MGD with a suspended solids concentration of 111 mg/L, what is the sludge age?
4.3 days
4.4 days
4.5 days
4.6 days
The MLSS concentration in the aeration tank is 2960 mg/L. The aeration tank is 110 ft long by 50 ft wide and operates at a depth of 14 ft. If the influent flow to the tank is 1.98 MGD and has a suspended solids concentration of 110 mg/L, what is the sludge age?
7.9 days
8 days
14 days
11 days
An oxidation ditch has a volume of 211,000 gal. The 270,000-gpd flow to the oxidation ditch has a suspended solids concentration of 205 mg/L. If the MLSS concentration is 3810 mg/L, what is the sludge age in the oxidation ditch?
1.46 days
14.6 days
146 days
None of the followings
The desired sludge age for a plant is 5 days. The aeration tank volume is 780,000 gal. If 2810 lb/day suspended solids enter the aeration tank and the MLSS concentration is 3740 mg/L, how many pounds per day MLSS should be wasted?
806 lb
807 lb
8067.68 lb
806.76 lb
A mixed liquor sample with a 4000 mg/L total suspended solid concentration settles to a volume of 500 mL after 30 minutes in a 1 L cylinder. If the 30 minutes settling volume for the mixed liquor sample was 25%, what is the sludge volume index?
125
62.5
120
65.2
The settleability test indicates that, after 30 min, 600 mL of sludge settle in the 1-L graduated cylinder. If the mixed liquor suspended solids (MLSS) concentration in the aeration tank is 3600 mg/L, what is the sludge volume index?
155.2
166.67
16.67
15.52
The MLSS concentration in an aeration tank is 3500 mg/L. If the activated sludge settleability test indicates 250 mL settled in the 1-liter graduated cylinder, what is the sludge density index?
1.1
1.2
1.3
1.4
The MLSS concentration in an aeration tank is 4500 mg/L. If the activated sludge settleability test indicates 450 mL settled in the 1-liter graduated cylinder, what is the sludge density index?
1
2
3
4
The MLSS concentration in an aeration tank is 5000 mg/L. If the activated sludge settleability test indicates 250 mL settled in the 1-liter graduated cylinder, what is the sludge density index?
1
2
3
4
