CME Water & Wastewater Systems Flashcards

What is the purpose of a sanitary sewer system's lift (pump) station?

Answer: Pump wastewater to a higher elevation when gravity flow is not feasible

Lift stations pump sewage uphill to overcome topographic barriers where gravity-only sewer routing is impractical or uneconomical.

Which treatment process removes the majority of suspended solids and biochemical oxygen demand (BOD) in secondary wastewater treatment?

Answer: Activated sludge or biological treatment

Secondary treatment using activated sludge or other biological processes removes 85–95% of BOD and suspended solids through microbial action.

What document establishes the effluent limits a municipal wastewater treatment plant must meet when discharging to a water body?

Answer: NPDES Permit

An NPDES (National Pollutant Discharge Elimination System) permit sets the specific effluent limits a treatment plant must meet under the Clean Water Act.

In sewer system design, what does 'peaking factor' account for?

Answer: Ratio of peak instantaneous flow to average daily flow used for sizing sewers

The peaking factor is applied to average daily flows to size sewers and treatment facilities for the highest expected instantaneous or peak-hour flows.

Which sewer rehabilitation method installs a resin-impregnated liner inside an existing pipe without excavation?

Answer: Cured-in-place pipe (CIPP)

CIPP (cured-in-place pipe) involves inserting a resin-saturated felt tube and curing it in place to form a new pipe inside the deteriorated host pipe without digging.

What is the primary concern with combined sewer overflows (CSOs) in older US cities?

Answer: Discharge of untreated sewage and stormwater to waterways during rain events

CSOs occur when combined sewers overflow during storms, releasing untreated sewage mixed with stormwater directly into receiving waters, causing significant water quality impairment.