Course Glossary

This shows the specialized terms used in EarthWise Academy. This section contains all the definitions used in the various course glossaries used by each course.

Browse the glossary using this index

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Entries starting with: D

Detected Contaminant

Any contaminant detected at or above its detection limit.

  • (CCR01)Consumer Confidence Report (CCR) Overview (2338)

Detection Limit

The amount of a substance with that EPA has determined to be the minimum concentration that can be measured and reported with 99% confidence that the true value is greater than zero.

  • (CCR01)Consumer Confidence Report (CCR) Overview (2338)

Detention Time

The theoretical time that a parcel of water or other liquid spends in a particular treatment unit or reservoir.

  • (COA01) Coagulation – Part 1: The Chemistry of Coagulation (1248)

Diatomaceous Earth

A fine material made up mostly of the skeletal remains of single cell, microscopic algae with a rigid, box-like internal structure consisting mainly of silica.

  • (DBP40) Enhanced Coagulation – Basics (1280)

Digester Capacity

The total volume in gallons that a digester(s) can hold, or the volume used during the monitoring period, if not operating at full capacity.

  • (BIO10) Estimating Sludge Volume (2343)

Discharge Monitoring Report

Discharge Monitoring Report (DMR)


Substances that are added for the purpose of killing or inactivating the pathogenic (disease-causing) bacteria found in water.

Chlorine, Chloramines, & Chlorine Dioxide are disinfectants.

  • (DBP01) DBP Rule – Overview (1282)
  • (DBP02) DBP Rule Monitoring and Reporting – Job Aids (1283)
  • (DBP10) DBP Rule Monitoring and Reporting for Chlorine⁄Chloramines (1284)
  • (DBP13) DBP Rule Monitoring and Reporting for TTHM⁄HAA5 (1285)

Disinfection Byproducts Precursors

Organic substances that combine with disinfectants to form potentially carcinogenic compounds such as HAA5’s and TTHM’s.

  • (DBP43) Jar Testing for Process Control of Conventional Filtration: Part 1 (2019)

Dissolved Oxygen

Dissolved Oxygen (DO)

A measure of the amount of free or molecular oxygen dissolved in water, expressed as:

  1. mg/L, which is the absolute amount of oxygen dissolved in the water mass or
  2. the percentage saturation of water with O2 (% sat).
    • (BNR01) Nitrification and Denitrification – An Introduction to Nitrogen Removal (1485)
    • (BNR02) Nitrification Factors – Suspended Growth Treatment Systems (1821)


DMR – Discharge Monitoring Report

  • (BIO10) Estimating Sludge Volume (2343)

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