A Sewage Treatment Plant (STP) is designed to treat wastewater before it is discharged or reused. To ensure the treated water meets environmental standards, routine laboratory testing is essential. These tests require a variety of laboratory chemicals and reagents for accurate analysis.
In this article, we discuss the basic chemicals required for routine STP water quality testing.
If you're new to laboratory water testing, you may also find our guide on Laboratory Chemicals vs Reagents: What's the Difference? helpful. Understanding the difference between laboratory chemicals and analytical reagents can help you choose the right products for accurate STP testing.
1. pH Testing
Purpose: Measures whether the water is acidic or alkaline.
1. pH Buffer Solution (pH 4.00)
2. pH Buffer Solution (pH 7.00)
3. pH Buffer Solution (pH 10.00)
Note: These buffer solutions are mainly used for pH meter calibration.
2. Dissolved Oxygen (DO) Test
Purpose: Determines the amount of dissolved oxygen available in water.
Manganous Sulphate Solution
Alkaline Iodide Azide Reagent
Concentrated Sulphuric Acid
Sodium Thiosulphate Solution
Starch Indicator
3. Chemical Oxygen Demand (COD) Test
Purpose: Measures the amount of oxygen required to chemically oxidize organic matter.
1. Potassium Dichromate
2. Sulphuric Acid Reagent with Silver Sulphate
3 .Mercuric Sulphate
4. Ferroin Indicator.
5. Ferrous Ammonium Sulphate (FAS)
4. Biochemical Oxygen Demand (BOD) Test
Purpose: Measures biodegradable organic pollution in wastewater.
1 .Phosphate Buffer Solution
2 .Magnesium Sulphate Solution
3 .Calcium Chloride Solution
4. Ferric Chloride Solution
5. Seed Inoculum (when required)
5. Chloride Test
Purpose: Determines chloride concentration in wastewater.
1. Silver Nitrate Solution
2. Potassium Chromate Indicator
6. Alkalinity Test
Purpose: Measures the buffering capacity of water.
1.Sulphuric Acid Standard Solution
2.Phenolphthalein Indicator
3.Methyl Orange or Mixed Indicator
7. Residual Chlorine Test
Purpose: Measures free chlorine after disinfection.
1. Potassium Iodide
2. Starch indicator
3. Sodium Thiosulphate
4. Acetic Acid
8. Total Suspended Solids (TSS)
Purpose: Measures suspended particles in wastewater.
1. Glass Fiber Filter Paper
2. Distilled Water
10. Total Dissolved Solids (TDS)
Purpose: Determines dissolved solids present in water.
1.Distilled Water
2. Conductivity Standard Solution (for meter calibration)