What is the required MLSS concentration if the desired solids loading rate is 40 lbs/day/sq ft for a clarifier with a flow of 6.5 MGD?

To determine the required Mixed Liquor Suspended Solids (MLSS) concentration based on a solids loading rate and flow rate, you need to understand the relationship between these variables. The solids loading rate provides a means to calculate the necessary solids concentration to achieve the desired treatment performance in a clarifier.

In this scenario, the desired solids loading rate is 40 lbs/day/sq ft, and the flow rate is 6.5 million gallons per day (MGD). The first step is to convert the flow rate from MGD to cubic feet per day, as the solids loading rate is given in pounds per square foot per day.

1 MGD is equivalent to approximately 7.48 cubic feet, which means:

[

6.5 \text{ MGD} \times 7.48 \text{ cf/MG} = 48.62 \text{ cubic feet/day}

]

Next, to find the area of the clarifier, which is necessary for calculating the actual solids loading in terms of lbs/day, we would divide the total flow by the loading rate:

[

Solids , Loading , Rate = \frac{Total , Solids , Load}{Area}

]

Rearranging