GB/T 15818-2018 in English

Interpretation of GB/T 15818-2018 Test Method for Biodegradability of Surfactants

Standard Overview

GB/T 15818-2018 standard specifies the test method for the primary biodegradability of surfactants, which is applicable to various types of surfactants, including anions, cations, zwitterions and fatty acids.

• The requirements for shaking culture machines have been modified
• New basic nutrient solution has been added
• The cotton wool filtration method has been deleted
• The determination method for fatty acid surfactants has been added
• The determination method for surface tension method has been added

Comparison of standard frameworks

Technical Specification Interpretation

Reagent and Instrument Requirements

The standard specifies detailed reagent preparation methods and instrument parameters, for example:

• Basic nutrient solution: including ammonium chloride, dipotassium hydrogen phosphate and other ingredients
• Oscillating culture machine: amplitude ≥ 20mm, frequency range 40-300 times/min
• Microbial source: activated sludge mass concentration controlled at 10-20 g/L

Detailed explanation of test steps

The test procedures in the standard include:

1. Sample preparation: prepare the surfactant into a neutral solution
2. Basic nutrient solution preparation: adjust the formula according to different types of surfactants
3. Test solution preparation: Add standard control solution and blank test solution
4. Activated sludge inoculation: Add activated sludge suspension into the culture bottle
5. Oscillating culture: Cultivate for 72 hours under set conditions
6. Biodegradation determination: Determine by spectrophotometry or surface tension method

Implementation suggestions

To ensure the accuracy and reliability of the test, it is recommended that:

• Strictly control reagent preparation and instrument calibration
• Select an appropriate determination method according to the type of surfactant (such as methylene blue method, cobalt thiocyanate method, etc.)
• Properly save the culture condition data for subsequent analysis and traceability