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50 terms

Wastewater Grade 2 t/f

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Hydraulic loading to a facultative wastewater pond is measured in units of Inches/day
True
An Imhoff cone is often used to measure the effectiveness of primary sedimentation
True
A well-operating primary clarifier will generally remove nearly all settleable solids
True
The trickling filter recirculation ratio is calculated as follows Qr/Q
True
Chlorine dose = Lbs of chlorine/day divided by the flow in MGD
False
needs 8.34
A combined sewer carries domestic waste , industrial waste and storm water
True
Algae use oxygen at night in a facultative pond
True
The pH of digesting sludge in a healthy anaerobic digester should be near 7.0
True
Percent volatile solids reduction equals :
IN-OUT over IN-(IN x OUT) X 100%
True
A chlorine dose of 5 ppm or mg/L is equivalent to adding 5 lbs. of chlorine per million pounds wastewater flow
True
The main function of a secondary digester in normal operation is to allow liquids and solids to separate
True
Poor grit removal would affect the operation of a anaerobic digester
True
BOD removal efficiency in a well-operating primary clarifier is generally in the range of 25-40%
True
The M in the F to M ratio refers to the pounds of mixed liquor suspended solids under aeration in an activated sludge aeration tank
False
A barminutor may be set to start automatically based on a loss of head pressure through this device
True
Ppm ( parts per million) and mg/L are essentially equivalent units
True
The terms "high rate" and "low rate" refer to the rate at which gas is produced in an anaerobic digester
False
A grit chamber with a flow velocity of 0.2 ft/sec may allow a significant quantities of volatile material to setle out
True
Secondary wastewater treatment processes generally involve the aerobic decomposition of organic matter
True
Preliminary wastewater treatment is used to protect pumping equipment and to facilitate subsequent treatment processes
True
Oxygen may be referred to as either combine oxygen or free molecular oxygen
True
Solids in a wastewater effluent may undergo aerobic decomposition in the receiving water if dissolved oxygen is available.
True
The MPN test measures the number of pathogens in a wastewater effluent
False
Wastewater treatment ponds that receive raw wastewater are called stabilization ponds
True
Pre-aeration of raw wastewater may result in better removal efficiencies in the primary clarifier
True
Domestic wastewater contains approximately 0.1% Total solids.
True
A well-operating anaerobic digester should have a CO2 concentration of more than 40%
False
Wastewater having a pH of 7.3 is slightly basic or alkaline
True
Gas production in an anaerobic digester results from the destruction of organic solids
True
Pre- chlorination of raw wastewater requires that a chlorine residual of at least 0.5mg/L be attained in order to assure odor control
False
Velocity in a grit chamer may be controlled by a proportional weir
True
The only function of flights in a rectangular sedimentation tank is to push the settled sludge toward the sludge hopper
False
Percent efficiency of solids or BOD removal is calculated using the following formula:
IN-OUT / IN X 100
True
Velocity is an important consideration in the operation of a collection system or a grit chamber
True
One acre-ft of water contains 45,336 ft cubed
False
MGD and ft cubed/sec are both units of flow
True
BOD5 and SS are both used as measures of the strength of wastewater
True
Hydraulic loading to a clarifier is expressed in units of gallons per day
False
The solids in primary sludge contains both a volatile and fixed part
True
Chlorine feed rate and chlorine residual are both usually expressed in units of ppM
False
SVI is a measure of the rate at which activated sludge mixed liquor settles
False
A shear pin that constantly breaks should be replaced with a pin of greater strength
False
Septic sludge probably have a low pH
True
When computing anaerobic digester organic loading one must take into account the loss of solids in the digester supernatant
False
The F in the F to M ratio may be measured as either BOD or COD
True
An anaerobic digester is generally equipped with a combination pressure-vacuum relief valve
True
Extended aeration activated sludge plants are designed to have aeration tanks that can hold approximately one day's flow
True
A 5 foot deep facultative pond is usually mixed with floating aerators during cloudy days
False
A parshall flume measures velocity of the influent flow
False
When BOD and COD are measured on a primary effluent sample the BOD will generally be greater than the COD
False