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An Introduction to Secondary Wastewater Treatment

COURSE NO: C04-022
An Introduction to Secondary Wastewater Treatment
Course Highlights

This online engineering PDH course will introduce you to processes and equipment for secondary treatment of wastewater. You will be introduced to descriptions, functions and design considerations for trickling filter plants, activated sludge plants, and wastewater treatment ponds.  You will be introduced to special considerations for wastewater treatment plants in hot and cold climates.  You will learn how the secondary treatment processes work together with the preliminary, primary, tertiary and sludge handling processes to form a complete wastewater treatment plant.


Wastewater treatment is usually characterized as consisting of four sequential processes: preliminary, primary, secondary and tertiary treatment. 


This 4 PDH online course is intended for civil, environmental and chemical engineers as well as construction professionals seeking an introduction to secondary wastewater treatment.

Learning Objectives

This PE continuing education course is intended to provide you with the following specific knowledge and skills:

  • Understanding design basis and criteria for trickling filter plants
  • Learning about the different dosing intervals for different classifications of trickling filters
  • Learning about the biochemical oxygen demand (BOD) efficiency of different classifications of trickling filters
  • Learn how recirculation increases BOD removal efficiency in high rate trickling filter processes
  • Understanding the four common flow diagrams for single-stage and two-stage trickling filter plants
  • Understanding why loading rate is the key design factor whether the surface application is continuous, intermittent, constant or varying rate
  • Understanding the importance of ventilation in providing aerobic conditions for effective treatment
  • Understanding how performance of trickling filters will be affected by temperature changes in the wastewater and filter films
  • Learning about design formulas for determining BOD removal efficiencies for single- and two-stage trickling filters
  • Understanding the purpose of secondary sedimentation tanks
  • Learn about the conventional plug-flow, step aeration,  contact stabilization, and completely-mixed activated sludge processes
  • Learning about the closed-loop reactor (oxidation ditch) extended aeration process
  • Learning about the classifications of wastewater treatment ponds
  • Learning about shallow and aerated aerobic ponds
  • Learning about aerobic-anaerobic and facultative wastewater treatment ponds
Course Document

In this professional engineering CEU course, you need to review the course document titled, "An Introduction to Secondary Wastewater Treatment".

To view, print and study the course document, please click on the following link(s):
Introduction to Secondary Wastewater Treatment (1.14 MB)
Course Quiz
Once you complete your course review, you need to take a multiple-choice quiz consisting of twenty five (25) questions to earn 2 PDH credits. The quiz will be based on the entire document.


The minimum passing score is 70%. There is no time limit on the quiz, and you can take it multiple times until you pass at no additional cost.
Certificate of Completion

Upon successful completion of the quiz, print your Certificate of Completion instantly. (Note: if you are paying by check or money order, you will be able to print it after we receive your payment.) For your convenience, we will also email it to you. Please note that you can log in to your account at any time to access and print your Certificate of Completion.

To buy the course and take the quiz, please click on: