Water Quality & Treatment Flashcards

In drinking water treatment, what is the purpose of maintaining a chlorine 'residual' throughout the distribution system?

Answer: To provide continuous disinfection protection against pathogen growth and regrowth during distribution

A minimum chlorine residual (typically 0.2 mg/L free chlorine at the tap) is maintained throughout the distribution system to prevent microbial contamination and regrowth between the treatment plant and consumers.

What is the difference between Total Suspended Solids (TSS) and Total Dissolved Solids (TDS) in water quality analysis?

Answer: TSS is retained on a filter (typically 0.45 μm); TDS passes through the filter

TSS is determined by filtering a water sample through a 0.45 μm filter and weighing the retained solids, while TDS consists of dissolved ions and molecules that pass through the filter.

Which water quality standard provision under the Clean Water Act designates specific bodies of water for a primary intended use such as 'cold water fishery' or 'primary contact recreation'?

Answer: Use Designations in Water Quality Standards

States assign use designations to water bodies (aquatic life support, primary/secondary contact recreation, drinking water supply) as part of water quality standards, which then drive the numeric criteria applied to protect those uses.

What does the term 'water hammer' describe in a drinking water distribution system, and what hazard does it present?

Answer: A pressure surge caused by rapid flow velocity changes that can damage pipes and joints

Water hammer is a hydraulic shock wave created when flowing water is suddenly stopped (by fast valve closure or pump shutdown), producing pressure surges that can rupture pipes, damage fittings, and compromise system integrity.

A municipality uses UV disinfection as a final treatment step before distribution. What is the primary advantage of UV over chlorination for drinking water disinfection?

Answer: UV does not produce disinfection byproducts (DBPs) such as trihalomethanes

UV disinfection inactivates pathogens by damaging their DNA without adding chemicals, so it does not generate regulated disinfection byproducts like trihalomethanes (THMs) or haloacetic acids (HAAs) that form when chlorine reacts with natural organic matter.

What is the primary environmental concern associated with pharmaceutical and personal care products (PPCPs) detected in surface water and groundwater?

Answer: PPCPs are endocrine-disrupting compounds that can affect aquatic organism reproduction and development at trace concentrations

Many PPCPs are endocrine-disrupting compounds (EDCs) that interfere with hormonal signaling in aquatic organisms at parts-per-trillion concentrations, causing reproductive impairment, intersex conditions, and population-level effects.