Operator math practice quiz
10 questions, free, no sign-up. Answers and reasons appear when you check your answers, and you can try again as many times as you like.
Ten operator math questions of the kind found on certification exams: area, overflow and weir rates, detention time, volume, alkalinity, digester solids, volatile solids reduction, retention time and methane.
Practice quiz: it does not give a certificate. Certificates are issued to paid students after passing the certification quiz for their class.