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More Wastewater Math Problems & Charts

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If the volatile solids concentration in raw sludge is 66% and the volatile solids concentration in the digested sludge is 56%, what was the volatile solids reduction?

Match the following:

What is the formula for the solids loading rate on a final clarifier in an activated sludge plant?

mg/L x 8.34 x MGD is the formula for calculating

A. Chlorine demand

B. lbs

C. lbs/day

D. Volume of a cylindrical tank

Your raw TSS is 230 mg/L and your primary effluent TSS is 175 mg/L. Your flow is 25 MGD. Calculate the lbs/day of TSS removed and % removal efficiency.

Click on the thumbnail below for a chart of BOD and TSS math and have some fun!!!

Click on the thumbnail below for a chart of pump station math for cylindrical tanks and have some fun!!!

Click on the thumbnail below for a chart of pump station math for rectangular tanks and have some fun!!!

Click on the thumbnail below for a chart of pipe math and have some fun!!!

The formula for the volume of a rectangular tank is

A.  (Length)(Width)

B.  (0.785)(Diameter²)

C.  (Length)(Width)(Height)

D.  (0.785)(Diameter²)(Height)

The formula for the volume of a cylindrical tank is

A.  (Length)(Width)

B.  (0.785)(Diameter²)

C.  (Length)(Width)(Height)

D.  (0.785)(Diameter²)(Height)

Given a tank measures 50 feet long, 25 feet wide, and 15 ft deep, calculate:

• Surface area in ft²
• Cross-sectional area in square feet
• Volume in cf
• Capacity in gallons

The flow through an activated sludge plant is 15 mgd.  The BOD of the primary effluent is 110 mg/L and the BOD of the final effluent is 8 mg/L.  The rate of air flow to the aeration tank is 2,000 cfm.  The MLSS is the aeration tank is 2,500 mg/L.  The 30-minute settleable solids test is 225 mL/L.  The TSS of the primary effluent is 115 mg/L and the TSS of the final effluent is 12 mg/L.  The return sludge ratio is 20%.  60,000 gallons of 2% sludge are wasted each day.  The flow is split evenly between two rectangular aeration tanks.  All tanks are the same size.  Each tank is 175 feet long, 75 feet wide, and 12 feet deep.

The perimeter of one aeration tank is ________ feet.

 

 

The surface area of one aeration tank is ________ square feet.

 

 

The volume of one aeration tank is ________ cubic feet.

 

 

The volume of one aeration tank is ________ 1000-cubic feet.

 

 

The total volume of both aeration tanks together is ________ cubic feet.

 

 

The total volume of both aeration tanks together is ________ 1000-cubic feet.

 

 

One aeration tank holds  ________ gallons.

 

 

One aeration tank holds  ________ million gallons.

 

 

The two aeration tanks together hold  ________ gallons.

 

 

The two aeration tanks together hold  ________ million gallons.

 

 

The return sludge flow is ________ mgd.

 

 

The applied flow to the aeration tanks is ________ mgd.

 

 

The applied flow to one aeration tank is ________ mgd.

 

 

The applied flow to one aeration tank is ________ gpd.

 

 

The detention time is ________ hours.

 

 

The total organic load to both aeration tanks is ________ lbs BOD/day.

 

 

The organic load to one aeration tank is ________ lbs BOD/day.

 

 

The organic loading rate on one aeration tank is ________ lbs BOD/day/1000-cf.

 

 

The MLSS in one aeration tank is ________ lbs MLSS.

 

 

The MLSS in both aeration tanks is ________ lbs MLSS.

 

 

The F/M is ________.

 

 

The total amount of sludge wasted daily is ________  lbs WAS/day.

 

 

The amount of sludge wasted from each aeration tank is ________ lbs WAS/day.

 

 

The SRT is ________ days.

 

 

The effluent TSS is ________ lbs TSS/day.

 

 

The MCRT is ________ days.

 

 

The influent TSS is ________ lbs TSS/day.

 

 

The sludge age is ________ days.

 

 

The SVI is ________

The flow through an activated sludge plant is 15 mgd.  The BOD of the primary effluent is 110 mg/L and the BOD of the final effluent is 8 mg/L.  The MLSS is the aeration tank is 2,500 mg/L.  The 30-minute settleable solids test is 225 mL/L.  The TSS of the primary effluent is 115 mg/L and the TSS of the final effluent is 12 mg/L.  The return sludge ratio is 20%.  60,000 gallons of 2% sludge are wasted each day.  The flow is split evenly between two equal-sized rectangular aeration tanks and final clarifiers.  Each aeration tank is 175 feet long, 75 feet wide, and 12 feet deep.  Each final clarifier has a 75 feet diameter, a SWD of 8 feet, and they are 12 feet deep in the center.

The circumference of a final clarifier is ________ feet.

 

 

The surface area of a final clarifier is ________ square feet.

 

 

The volume of a final clarifier is ________ cubic feet.

 

 

A final clarifier holds  ______ gallons.

 

 

The detention time of a final clarifier is _______ minutes.

 

 

The detention time of a final clarifier is _______ hours.

 

 

The surface settling rate of a final clarifier is _______ gpd/square foot

 

 

The weir overflow rate of a final clarifier is ________ gpd/ft

 

 

The solids loading rate of a final clarifier is ________ lbs/day/sq ft

 

 

The BOD removed is ______ mg/L.

 

 

The BOD removed is ______ lbs/day.

 

 

The BOD discharged by the plant is ______ lbs/day.

 

 

The TSS removed is ______ mg/L.

 

 

The TSS removed is ______ lbs/day.

 

 

The TSS discharged by the plant is ______ lbs/day.

 

 

The BOD removal efficiency is _____ %.

 

 

The TSS removal efficiency is _____ %.

The surface area of a tank 120 feet in diameter and 14 feet deep is ________ ft².

The surface area of a tank 90 feet in diameter and 9 feet deep is _____ ft².

The cross-sectional area of a tank 100 ft long, 25 ft wide, and 12 ft deep is _____ ft².

The surface area of a tank 100 feet long, 25 feet wide, and 12 feet deep is _____ ft².

A lot that measures 1,200 feet by 2,500 feet contains ______ acres.

The strength of a chemical solution made with 6 pounds of chemical and 55 gallons of water is _____ %.

200 gallons of a 2.5% solution contains _____ pounds of chemical.

Two solutions are being combined.  250 gallons of a solution containing 1.5 lbs of chemical per gallon of solution is being added to 1,500 gallons containing 4.8 lbs of chemical per gallon of solution.  The solution contains _____ pound(s) of chemical.

Two solutions are being combined. 250 gallons of a solution containing 1.5 lbs of chemical per gallon of solution is being added to 1,500 gallons containing 4.8 lbs of chemical per gallon of solution.  The weight of chemical in the new solution is _____ lbs/gal.

A drum contains 55 gallons of a chemical solution with a specific gravity of 1.12. The dry chemical weighs _______ pounds.

A dosage of 7 mg/L into a flow of 250,000 gpd uses ________ lbs/day of chemical.

Twenty-five pounds of chemical per day are being added to a flow of 500 gpm is _______ mg/L.

The maximum rate for a chemical feeder is 640 lbs/day. The feed rate is _____ pounds/minute.

The solution in a 15 foot by 35 foot by 55 foot tank with a specific gravity of 1.05 weighs _____ pounds.

A drum contains 55 gallons of a solution with a specific gravity of 1.25.  The empty drum weighs 25 pounds.  The weight of the filled drum is _____ pounds.

55 gallons of a 0.15% chemical solution contains _____ pound(s) of dry chemical.

A feed pump lowers a 15 foot diameter chemical solution tank containing a 4.5% solution 8 inches in 20 minutes.  The pump delivers ______ pounds/day of solution.

A feed pump that lowers a 15 foot diameter chemical solution tank 8 inches in 20 minutes delivers _______ gpd.

A pump that lowers a 15 foot diameter chemical solution tank 8 inches in 20 minutes delivers _______ gpm.

A slurry was prepared by adding two 40 pound bags of a chemical to a 55 gallon drum and adding enough water to fill the drum.  The slurry contains _____ pound(s) of chemical.

If a bag of polymer weighs 60 pounds and contains 4.5% of a certain chemical by weight, the weight of that chemical is ______ pounds.

You need to control an algae bloom in your 20,000,000 gallon raw water reservoir.  The herbicide directions recommend applying 25 pounds/acre.  If the average depth of the reservoir is 15 feet and each bag contains 40 pounds of herbicide, you need ____ bags.

To dose a flow of 0.6 mgd at 1.8 mg/L, you need ____ 40 pound bags of the chemical.

You try to maintain a 120 day supply of all chemicals.  If a bag contains 40 pounds of chemical, how many bags of a chemical are needed to dose a flow of 0.6 mgd at 1.8 mg/L?

The hopper for your chemical feeder is conical in shape with a reserve tank on top.  The hopper has a diameter of 12 feet and a depth of 8 feet.  The reserve tank is 20 feet high.  The total volume of the hopper and the reserve tank is _______ ft³.

The hopper for your chemical feeder is conical in shape.  If it has a diameter of 12 feet and a depth of 8 feet, the volume of the hopper is _______ ft³.

Calculate the molecular weight of H₂CO₃.  The atomic weight of calcium is 40, oxygen is 16, carbon is 12, and hydrogen is 1.

Calculate the molecular weight of H₂O.  The atomic weight of calcium is 40, oxygen is 16, carbon is 12, and hydrogen is 1.

Calculate the molecular weight of Ca(HCO₃)₂.  The atomic weight of calcium is 40, oxygen is 16, carbon is 12, and hydrogen is 1.

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