MLSS Given BOD Load Applied To Aeration System Calculator

Formula Used:

\[ MLSS = \frac{(Total\ Microbial\ Mass \times Sewage\ Flow \times Influent\ BOD)}{(Volume\ of\ Tank \times Daily\ BOD)} \]

Total Microbial Mass:

Sewage Flow:

m³

Influent BOD:

kg/m³

Volume of Tank:

m³

Daily BOD:

MLSS:

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1. What is MLSS?

MLSS (Mixed Liquor Suspended Solids) is the concentration of suspended solids in the mixed liquor within an aeration tank during the activated sludge process. It represents the total microbial mass present in the system.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ MLSS = \frac{(Total\ Microbial\ Mass \times Sewage\ Flow \times Influent\ BOD)}{(Volume\ of\ Tank \times Daily\ BOD)} \]

Where:

Total Microbial Mass — Cumulative mass of microorganisms (kg)
Sewage Flow — Flow into the aeration tank (m³)
Influent BOD — BOD concentration in incoming sewage (kg/m³)
Volume of Tank — Capacity of flocculation and mixing tank (m³)
Daily BOD — Daily BOD load (kg)

Explanation: This formula calculates the MLSS concentration based on the relationship between microbial mass, sewage flow, BOD inputs, and tank volume.

3. Importance of MLSS Calculation

Details: Accurate MLSS calculation is crucial for monitoring and controlling the activated sludge process, ensuring optimal treatment efficiency, and maintaining proper microbial population balance in wastewater treatment systems.

4. Using the Calculator

Tips: Enter all values in appropriate units (kg for mass, m³ for volume/flow, kg/m³ for concentration). All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for MLSS in activated sludge systems?
A: MLSS typically ranges from 1500-4000 mg/L (1.5-4.0 kg/m³) in conventional activated sludge systems.

Q2: How does MLSS affect treatment efficiency?
A: Higher MLSS concentrations generally improve treatment efficiency but require more oxygen and may cause settling problems if too high.

Q3: What factors can affect MLSS concentration?
A: Wastewater characteristics, sludge age, temperature, aeration capacity, and sludge wasting rates all affect MLSS concentration.

Q4: How often should MLSS be monitored?
A: MLSS should be monitored daily in most treatment plants to maintain optimal process control.

Q5: What is the relationship between MLSS and F/M ratio?
A: The Food to Microorganism (F/M) ratio is calculated using MLSS. Lower F/M ratios indicate more microorganisms relative to the food supply.