A primary sedimentation tank that has a removal efficiency of 65% and settles out solids from a wastewater that has concentration of 220 mg/L. The wastewater flows into the sedimentation tank at a rate of 2.35 million gallons per day (MGD). How many tons (as dry mass) of primary sludge are produced each day?
The answer is 1.40 tons, but I don't know how to do it.
tons=.65*.220g/liter*3.9liters/gal*2.35e6gallons/day*ton/9.06e5 grams=140 tons
those tons are US tons, not metric.
To find the amount of primary sludge produced each day, you need to follow these steps:
Step 1: Convert flow rate to liters per day
- The given flow rate is 2.35 MGD (million gallons per day)
- To convert gallons to liters, multiply by 3,785.41 (1 gallon = 3,785.41 liters)
- So, the flow rate is 2.35 MGD * 3,785.41 L/gallon = 8,877,293.35 liters per day
Step 2: Calculate the mass of suspended solids (SS) removed each day
- The SS concentration in the wastewater is given as 220 mg/L
- Multiply the SS concentration by the flow rate to find the total mass of SS removed per day:
Mass of SS removed = 220 mg/L * 8,877,293.35 L/day
Step 3: Calculate the mass of primary sludge produced
- The removal efficiency of the primary sedimentation tank is given as 65%
- Multiply the mass of SS removed by the removal efficiency:
Mass of primary sludge = (220 mg/L * 8,877,293.35 L/day) * (65/100)
Step 4: Convert mass of primary sludge to tons (as dry mass)
- The given answer is in tons, so we need to convert the mass from milligrams to tons:
1 ton = 1,000,000 mg
- Divide the mass of primary sludge by 1,000,000 to convert it to tons:
Mass of primary sludge (in tons) = Mass of primary sludge (in mg) / 1,000,000
Now let's do the calculations:
Mass of SS removed = 220 mg/L * 8,877,293.35 L/day = 1,952,804,337 mg/day
Mass of primary sludge = (1,952,804,337 mg/day) * (65/100) = 1,268,982,227.05 mg/day
Mass of primary sludge (in tons) = 1,268,982,227.05 mg/day / 1,000,000 = 1.27 tons (rounded to two decimal places)
Therefore, the amount of primary sludge produced each day is approximately 1.27 tons (as dry mass). Note that the given answer of 1.40 tons may have used slightly different calculations or rounding.