Guest Column | February 15, 2017

Math Solutions: Certification Examination Prep Calculations

Wastewater Dan Theobald

By Daniel Theobald, "Wastewater Dan"


The written examination, generally the mathematics portion, is repeatedly a considerable hurdle operators face in the certification process.

While it is natural to be worried about the unknown, being apprehensive can lead to less achievement. Conversely, knowing what to expect more likely leads to relaxation and accomplishment — and can ultimately help you pass the exam.

This tool for operators, represented through video tutorials, offers mathematical templates to help prepare you and/or your colleagues for Wastewater Certification Examination math word problems via calculation solutions.

The tool also provides definitions, explanations, and alternative applications for the calculations beyond the specific examples presented. In addition to operators, it may also serve educators, engineers, regulators, and others.

Representative Certification Examination Prep math word problems and exact step-by-step solutions are presented  below.

Certification Examination Prep Calculation Solutions:

Calculate biochemical oxygen demand (BOD) (mg/L):

Calculate food-to-mass (F:M) ratio:

Calculate alkalinity required to convert ammonia:

Calculate lime (lbs) to stabilize sludge:

Calculate dry lime (lbs) in a slurry tank:

Convert infiltration rate in a pond from gallons to inches:

Calculate detention time with multiple flow sources:

Calculate total metals (lbs) from three flow sources:

Playlist of all 165-plus Math Solutions

This is the Certification Examination Prep Calculations presentation in my series of “Math Solutions.” If you have specific wastewater math queries, please submit a question

About Dan Theobald:

Known in the industry as “Wastewater Dan,” Daniel L. Theobald, proprietor of Environmental Services (, is a professional wastewater and safety consultant/trainer. He has more than 24 years of hands-on industry experience operating many variants of wastewater treatment processing units and is eager to share with others his knowledge about water conservation.

Theobald serves as an active consultant for industries looking to achieve and maintain improved wastewater treatment at reduced cost. He is a Lifetime Member of the Who’s Who Registry of Professionals and holds numerous certifications from wastewater management regulatory boards and professional organizations. Theobald contributed one chapter to the Water Environment Federation’s ( Manual of Practice # 37 (MOP-37), a technical manual resource guide for biological nutrient removal, published in 2013.

Image credit: "#2 Pencils," Carol VanHook © 2014, used under an Attribution 2.0 Generic license: