The key difference between MLSS and MLVSS is that MLSS measures the total solids weight of the given sample, whereas MLVSS measures the total volatile fraction of the total solids in the given sample.
The term MLSS stands for Mixed Liquor Suspended Solids, while the term MLVSS stands for Mixed Liquor Volatile Suspended Solids. These terms are important in analytical chemistry, mainly in wastewater treatment plants, to evaluate the treatment process by analyzing the total solid content in the tanks.
CONTENTS
1. Overview and Key Difference
2. What is MLSS
3. What is MLVSS
4. MLSS vs MLVSS in Tabular Form
5. Summary – MLSS vs MLVSS
What is MLSS (Mixed Liquor Suspended Solids)?
The term MLSS stands for Mixed Liquor Suspended Solids. It is the concentration of suspended solids in an aeration tank (during the process of activated sludge formation) in wastewater treatment. Primarily, this parameter is measured using the unit milligrams per liter (mg/L). However, we can measure activated sludge mostly in grams per liter (g/L). This is equal to kilograms per cubic meter. This mixed liquor can be described as a combination of raw or unsettled wastewater or pre-settled wastewater and activated sludge within the aeration tank.
MLSS mostly contains microorganisms and non-biodegradable suspended matter. It is an important part of the activated sludge process because it ensures a sufficient quantity of active biomass for the applied quantity of organic pollutants to consume at any time. We call it the food to microorganism ratio or F/M ratio.
It is important to maintain this ratio in order to get a higher consumption of food by the biomass. This, in turn, minimizes the loss of residual food in the effluent. Moreover, the higher the consumption of biomass, the lower the biochemical oxygen demand (BOD).
What is MLVSS (Mixed Liquor Volatile Suspended Solids)?
The term MLVSS stands for Mixed Liquor Volatile Suspended Solids. Generally, we can describe it as the microbiological suspension in the aeration tank of an activated-sludge biological wastewater treatment plant. We can use the unit mg/L to measure this parameter in the mixed liquor of an aeration tank.
Typically, biomass solids in a biological wastewater reactor are indicated as total suspended solids or TSS and volatile suspended solids or VSS. The combination of recycled sludge with influent wastewater in the bioreactor gives mixed liquor volatile suspended solids. These solids contain biomass, non-degradable volatile suspended solids, and inert inorganic total suspended solids.
What is the Difference Between MLSS and MLVSS?
MLSS and MLVSS are important terms in analytical chemistry regarding wastewater treatment plants. They help to evaluate the treatment process by analyzing the total solid content in the tanks. MLSS stands for Mixed Liquor Suspended Solids, whereas MLVSS stands for Mixed Liquor Volatile Suspended Solids. The key difference between MLSS and MLVSS is that MLSS measures the total solids weight of the given sample, whereas MLVSS measures the total volatile fraction of the total solids in the given sample. Moreover, the solid in MLSS has microorganisms and non-biodegradable suspended matter, while MLVSS has biomass, non-degradable volatile suspended solids, and inert inorganic solid substances.
Below is a summary of the difference between MLSS and MLVSS in tabular form for side-by-side comparison.
Summary – MLSS vs MLVSS
The term MLSS stands for Mixed Liquor Suspended Solids, while the term MLVSS stands for Mixed Liquor Volatile Suspended Solids. The key difference between MLSS and MLVSS is that MLSS measures the total solids weight of the given sample, whereas MLVSS measures the total volatile fraction of the total solids in the given sample.
Reference:
1. “Waste Water Treatment Plant.” An Overview | ScienceDirect Topics.
Image Courtesy:
1. “Sewage treatment plant” By eutrophication&hypoxia (CC BY 2.0) via Flickr
2. “Treatment-plant-wastewater” (CC0) via Pixabay