Chemical Feed Systems & Dosing Flashcards

What type of pump is most commonly used for metering chemicals in water treatment plants?

Answer: Diaphragm metering pump

Diaphragm metering pumps deliver accurate, adjustable flow rates at high pressures, making them ideal for precise chemical dosing.

Which chemical is typically added to water to raise pH for corrosion control in the distribution system?

Answer: Lime (calcium hydroxide)

Lime increases water pH, which reduces corrosion of distribution system pipes and limits lead and copper leaching into drinking water.

When a 150-lb chlorine cylinder is being connected and there is risk of chlorine gas release, which personal protective equipment is required?

Answer: SCBA or supplied-air respirator with full-face protection

Chlorine gas is immediately dangerous to life and health (IDLH) at 10 ppm; SCBA or supplied-air respirators with full-face protection are required.

A gas chlorinator feeds at 8 lbs/day and plant flow is 2 MGD. What is the applied chlorine dose in mg/L?

Answer: 0.48 mg/L

Dose (mg/L) = Feed rate ÷ (Flow × 8.34): 8 lbs/day ÷ (2 MGD × 8.34) = 8 ÷ 16.68 = 0.48 mg/L.

What does 'flow-paced' chemical feeding mean?

Answer: Automatically adjusting chemical feed rate proportional to plant flow

Flow-paced feeders automatically vary the chemical feed rate in direct proportion to water flow, maintaining a consistent dose as flow changes.

Which chemical is used as an oxidizing agent for taste and odor control and iron/manganese removal in water treatment?

Answer: Potassium permanganate

Potassium permanganate (KMnO4) is a strong oxidizer used to remove iron, manganese, and hydrogen sulfide and to control taste and odor.

Sodium hypochlorite solution degrades most rapidly when exposed to which conditions?

Answer: High temperature and direct sunlight

Heat and UV light accelerate decomposition of sodium hypochlorite, reducing available chlorine concentration over time.