Operator Master
Level ILevel IIPractice ExamMath CenterLab CourseAbout
Start Practicing
Operator Master

Free exam practice for Washington wastewater treatment operators.

AboutSupportPrivacyTermsExam Disclaimer

Appearance

Operator Master is independent and is not affiliated with WPI, PSI, ABC or the Washington State Department of Ecology.
Math MasteryPercent Removal
Exit

Try independently

Solve It Your Way

BOD entering treatment is 200 mg/L. The effluent BOD is 20 mg/L. What percent was removed?

Choose one answer

Optional help

Use Only What You Need

Hints stay hidden unless you ask for them.

0
Family source boundary

Curated values teach the governed percent-removal relationship. They are not permit limits, treatment requirements, performance targets, design criteria, operating recommendations, certification weighting, or claims about a specific plant.

This Draft family uses selected mathematical facts only. It does not reproduce an official formula sheet or claim Washington exam weighting.

  • Printed page 5 of 10, Removal, %: (In − Out) ÷ In × 100%
  • Printed page 8 of 10, Abbreviations: BOD5, mg, L, and TSS