Know Your Process.

ORP measures the oxidizing or reducing tendency of water in millivolts — instantly distinguishing aerobic, anoxic, and anaerobic conditions. Learn how operators use it and what the exam tests.

COD measures total oxygen demand of all oxidizable material in hours — not 5 days like BOD. Learn the test, the COD/BOD ratio, CBOD vs. NBOD, and what the operator exam tests.

Primary treatment uses physical processes to remove settleable solids and floatables before biology takes over. Learn what it removes, how clarifiers work, common problems, and what the exam tests.

Anaerobic digestion stabilizes sludge, reduces volume, and produces biogas — all without oxygen. Learn the four stages, key parameters operators monitor, common digester upsets, and what the exam tests.

Dissolved oxygen is the single most important operational parameter in activated sludge. Learn target DO levels, what causes DO crashes, how aeration works, and what the exam tests.

Two processes, one goal: remove nitrogen. Learn how nitrification and denitrification work, the bacteria involved, operator controls, and exactly what the exam tests.

SVI measures how well activated sludge settles. Learn the formula, normal ranges, what a high SVI means, and how to run the settleometer test.

ORP measures the oxidizing or reducing tendency of water in millivolts — instantly distinguishing aerobic, anoxic, and anaerobic conditions. Learn how operators use it and what the exam tests.

COD measures total oxygen demand of all oxidizable material in hours — not 5 days like BOD. Learn the test, the COD/BOD ratio, CBOD vs. NBOD, and what the operator exam tests.

Primary treatment uses physical processes to remove settleable solids and floatables before biology takes over. Learn what it removes, how clarifiers work, common problems, and what the exam tests.

Anaerobic digestion stabilizes sludge, reduces volume, and produces biogas — all without oxygen. Learn the four stages, key parameters operators monitor, common digester upsets, and what the exam tests.

Dissolved oxygen is the single most important operational parameter in activated sludge. Learn target DO levels, what causes DO crashes, how aeration works, and what the exam tests.

Nitrification converts ammonia to nitrate. Denitrification converts nitrate to nitrogen gas. Learn how both processes work, what controls them, and what every Class II exam tests.

MLSS (Mixed Liquor Suspended Solids) is the headcount of your treatment army. Learn target ranges for different process types, how MLSS connects to SVI and sludge age, and what the operator exam tests.

A clear, practical guide — what's on the exam, how to study, and what separates operators who pass from those who don't.

Understand activated sludge from the ground up — how it works, why it fails, and what exam questions you'll see.

These are not the same problem — and the exam knows it. Learn the causes, how to identify each, and what to do.

Chlorine, UV, ozone — the exam tests all of them. A clear breakdown of how each works and what you need to know.

BOD is one of the most important parameters in wastewater treatment — and one of the most tested on the operator exam. Here's what it means and why it matters.

A complete walkthrough of the wastewater treatment process — preliminary, primary, secondary, and tertiary — and what operators need to know about each stage.

BOD, MLSS, SVI, F:M, HRT — if these acronyms trip you up on the exam, this guide is for you.

Key formulas, SVI ranges, safety numbers, and the most tested concepts for Class I and II exams — all in one place.

How much do wastewater operators make? Salary by certification level, state, and experience — plus how to earn more.

What wastewater operators actually do day-to-day — duties, skills, certification requirements, and what employers look for.

Seven steps from start to certificate — experience requirements, application process, exam prep, and what happens after you pass.

From application to certificate — a complete timeline including experience requirements, exam scheduling, and study time.