Question

Which of the following is an indicator of wastewater salinity?

• A. Conductivity
• B. Total suspended solids (TSS)
• C. pH level
• D. BOD level

Hint:

• Salinity is the measure of dissolved salts in water.
• Electrical Conductivity (EC) measures the ability of water to conduct electricity, which is directly related to the concentration of dissolved ions (salts).
• Higher salt content leads to higher conductivity.
• TSS measures undissolved particles. pH measures acidity/alkalinity. BOD measures organic pollution.

Answer 1

The Correct Option is A

Wastewater salinity refers to the concentration of dissolved salts (ions) in the water. These salts can include chlorides, sulfates, carbonates, sodium, potassium, calcium, magnesium, etc. A common and convenient indicator of the total dissolved salt content, and thus salinity, is electrical conductivity (EC) or simply conductivity.

• Conductivity (option a): Pure water is a poor conductor of electricity. Dissolved ionic substances (salts) increase the water's ability to conduct an electrical current. The higher the concentration of dissolved salts, the higher the electrical conductivity of the water. Therefore, conductivity is widely used as a quick and easy surrogate measure for total dissolved solids (TDS) and salinity.

Let's look at other options:

• Total Suspended Solids (TSS) (option b): This measures the mass of undissolved particulate matter suspended in the water. It is not a direct measure of dissolved salt content or salinity.
• pH level (option c): This measures the acidity or alkalinity of the water (hydrogen ion concentration). While certain dissolved salts can influence pH, pH itself is not a direct measure of overall salinity.
• BOD level (Biochemical Oxygen Demand) (option d): This measures the amount of oxygen required by microorganisms to decompose organic matter. It indicates organic pollution, not salinity.

Therefore, conductivity is the most direct indicator of wastewater salinity among the given options. \[ \boxed{\text{Conductivity}} \]