EXAM QUESTIONS AND VERIFIED ANSWERS
GRADED A+
◉ combined system of sewers. Answer: transports storm water
runoff and sewer together
◉ separate system of sewers. Answer: transports storm water runoff
and sewer separately (or directly to surface water)
◉ physical pollutants. Answer: -solids
high density- stones; swimming- wood; suspended particle-
grit,sand, organic, oil
-soluble materals
-emulsions
-gases
◉ chemical pollutants. Answer: -organic
biochemical, chemical oxygen demand-
-inorganic
nitrogen, phosphorus, toxic metals, cyanide
, ◉ BOD5. Answer: measure of biodegradable organic matter in
wastewater; gives oxygen consumed for biodegration of organic
compounds at 20 degrees Celsius over 5 days in 1 L w water, aerobic
◉ COD. Answer: measure of oxygen consumed from chemical
oxidizing agents under control; greater than BOD5
◉ flow of communal w water treatment plant. Answer: see picture
Wastewater -> primary treatment -> secondary -> tertiary-> treated
wastewater
Primary and secondary leads to sludge treatment which produces
treated sludge and water
◉ screens (primary). Answer: device with openings for removing
big, suspended or floating matter in sewage that would otherwise
interfere operation or damage equipment (man made objects,
debris, sand)
types: coarse, medium, fine, perforated plate, mesh, bar, self cleaning
step, radial bar
◉ dewatering (primary). Answer: refuse
screw press