Guest Column | May 4, 2016

Math Solutions: Efficiency And Recovery Calculations

Wastewater Dan Theobald

By Daniel Theobald, "Wastewater Dan"

“Wastewater Dan” helps wastewater operators understand efficiency and recovery with more easy-to-apply mathematical templates.

The thought process behind this presentation of “Math Solutions” comes from my 24-plus years of training experience in wastewater. I learned that many operators were held back from advancing their operating license because they struggled with the mathematics portion of wastewater operator certification examinations.

This tool for operators — represented through video tutorials — offers mathematical templates for performing accurate wastewater calculations. 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.

Efficiency and Recovery Calculations may have different requirements such as expressing the results as percent, square feet, cubic feet, increment of millions, or even incorporating a time element in calculation solutions. Also bear in mind that calculations involving pipes or shapes of tanks require explicit formula use.

Some common efficiency and recovery calculations are accessible below:

Efficiency Calculation:

Calculate Efficiency Rate (%):

Recovery Calculation and the Supporting Math Solutions:

Calculate Sludge Solids Filtered (lbs):


Calculate Filtered Cake Solids (lbs):


Calculate Solids Recovery Rate (%):



Playlist of 15-plus process control calculations (including efficiency and recovery)

Playlist of all 120-plus Math Solutions

This is the ‘Efficiency and Recovery 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.