Water Treatment Equipment & Technologies Flashcards

What is the primary mechanism by which activated carbon reduces chlorine from drinking water?

Answer: Chemical reduction (chemisorption) reaction with carbon surface

Chlorine is removed by activated carbon primarily through a chemical reduction reaction at the carbon surface, where chlorine is converted to chloride ion — not by physical adsorption alone.

In a whole-house sediment filtration system, which filter media configuration is called a 'multi-media' or 'multimedia' filter?

Answer: Layered beds of anthracite coal, sand, and garnet arranged by density

Multimedia filters use layered beds — typically anthracite on top, silica sand in the middle, and garnet on the bottom — allowing filtration from coarse to fine throughout the bed depth.

A water softener's 'capacity' is typically expressed in:

Answer: Grains of hardness removed between regenerations

Softener capacity is rated in grains, representing the total amount of hardness (calcium and magnesium) the resin can remove before it must be regenerated.

Which process does an electrodeionization (EDI) unit use to continuously remove ions from water without chemical regeneration?

Answer: Ion exchange resin regenerated by an electric current and ion-selective membranes

EDI combines ion exchange resin with ion-selective membranes and a DC electric current to continuously remove ions and regenerate the resin electrochemically, eliminating acid/caustic regenerant chemicals.

What is 'channeling' in a granular water treatment media bed and why is it problematic?

Answer: The formation of preferential flow paths through the media that bypass proper contact time

Channeling occurs when water carves pathways of least resistance through media, significantly reducing contact time and treatment effectiveness because much of the water bypasses the active media.

What is the purpose of an 'air injection' or 'air charge' system when treating water for iron and hydrogen sulfide removal?

Answer: To oxidize dissolved iron and hydrogen sulfide so they can be filtered out

Air injection introduces oxygen (from ambient air) into the water to oxidize soluble ferrous iron and hydrogen sulfide into insoluble forms that a downstream filter can capture.

Which NSF/ANSI standard specifically covers the performance and materials of reverse osmosis drinking water treatment systems?

Answer: NSF/ANSI 58

NSF/ANSI Standard 58 covers reverse osmosis drinking water treatment systems, including contaminant reduction performance, structural integrity, and materials safety.