How do I use ATU (allyl thiourea) for CBOD?

Document ID

Document ID TE182

Published Date

Published Date 27/05/2017
Question
How do I use ATU (allyl thiourea) for CBOD?
Summary
Allyl Thiourea (ATU) for CBOD analysis
Answer
ATU is a nitrification inhibitor mentioned in the 21st edition of Standard Methods for measuring CBOD. Standard Methods mentions that ATU may not work as well as TCMP (contained in Hach nitrification inhibitor), and concentrations above 2 mg/L will cause high results.

To use:

1. Dissolve 2 grams ATU in 1 liter water
2. Mix
3. Add 0.3 mL of this solution to each 300 mL BOD bottle.

The BOD bottles should be at least two-thirds full with diluted sample before adding the ATU.