Wastewater Characteristics Flashcards
T/F: The Federal Pretreatment Act defines industrial and commercial users differently from one another?
False: The Pretreatment Act does not distinguish between commercial and industrial users. It only defines domestic and industrial dischargers.
T/F Influent wastewater consists of domestic, industrial and commercial wastewater as well as contributions from inflow and infiltration?
True
T/F: Influent flow patterns reflect activities taking place in the service area?
True
An operator must take a piece of equipment out of service for maintenance. They will need to bypass pump wastewater around this piece of equipment during repairs. Assuming the WRRF has a typical diurnal flow pattern for domestic wastewater, when should maintenance be scheduled to minimize the amount of bypass pumping?
a: Midmorning
b: After lunch
c: Afternoon
d: Late evening
D
Which type of service area is likely to see the greatest variation in influent flow over a single day?
a; Town with 500 residents
b: City with separate domestic and storm sewers
c: City with more than 50,000 residents
d: Town without large commercial or industrial users
A
A WRRF receives wastewater from two ski resorts. Assuming the number of full-time residents in the service area is constant year around, when should the operator expect to see the highest influent flows and loads?
D
T/F When water use increases in a community, the influent wastewater concentrations
decrease assuming that the populations served has not changed.
True
T/F: An influx of stormwater from a combined sewer can increase average influent wastewater temperatures.
False: An influx of stormwater would likely decrease the influent temperature.
T/F: Septic conditions in the collection system upstream of the influent flow to a WRRF can cause the influent to be darker than the usual and can smell like rotten eggs.
True
T/F: Conductivity meters can also be used to accurately measure total dissolved solids?
False: While some conductivity meters give a TDS result, it is not a true measurement. TDS is calculated by applying a factor to the conductivity measurement. Although it is possible to build a correlation between conductivity and TDS for a particular wastewater, the only way to accurately measure TDS is by drying down a sample of filtered wastewater and weighing the residue left behind.
Domestic wastewater includes contributions from:
a: Significant industrial users
b: Categorical industrial users
c: Homes and businesses
d: Heavy industrial users
C
Fresh domestic wastewater will typically be:
a: White to pale yellow
b: Light brown to grey
c: Grey to black
d: Orange, yellow, or blue
B
Hydrogen sulfide is a concern for all of these reasons EXCEPT:
a: Poisonous at low concentrations
b: Corrodes concrete and metal
c: Potentially explosive
d: Smells strongly of garlic
D
Turbidity is a measure of:
a: Light scatter
b: Cloudiness
c: Solids concentration
d: Organic matter
A
Alkalinity is a measure of:
a: pH
b: Buffering capacity
c: Calcium carbonate concentration
d: Hydroxide content
B
