TEXAS WASTEWATER D UPDATED EXAM SCRIPT
QUESTIONS AND SOLUTIONS RATED A+
✔✔Hydrogen sulfide - ✔✔A dangerous byproduct of organic material decomposition
that increases with biological activity.
✔✔COD - ✔✔Chemical Oxygen Demand, typically ranging between 200 and 600 mg/L
in raw wastewater.
✔✔BOD:COD relationship - ✔✔The typical relationship between BOD and COD is 0.5:1
for raw wastewater.
✔✔Dissolved oxygen - ✔✔The amount of oxygen that can be maintained in water,
which decreases as water temperature increases.
✔✔CBOD test - ✔✔A test that measures carbonaceous BOD in biological process
effluent water, requiring a nitrification inhibitor.
✔✔Viruses in wastewater - ✔✔Viruses do not increase in number while in wastewater
as they require a host cell to reproduce.
✔✔Total Solids - ✔✔A term used to describe all solids contained within wastewater.
✔✔Ammonia levels in primary clarifier - ✔✔Increasing ammonia levels indicate a septic
condition in the primary sludge.
✔✔Storm events - ✔✔Commonly cause large amounts of sand, gravel, and grit to enter
the treatment plant.
✔✔Combined wastewater collection system - ✔✔A system that carries both sanitary
wastewater and stormwater runoff.
✔✔Total solids concentration - ✔✔In most wastewater, it is approximately 0.1%.
✔✔Suspended solids - ✔✔Approximately 30% of the total solids in wastewater are
characterized as suspended solids.
✔✔Dissolved solids - ✔✔Approximately 70% of the total solids in wastewater are
characterized as dissolved solids.
✔✔Septic conditions - ✔✔Caused by a lack of dissolved oxygen and the presence of
anaerobic bacteria.
✔✔Floatable scum - ✔✔Usually removed from wastewater in the primary clarifier.
,✔✔Aerobic bacteria - ✔✔Will deplete the dissolved oxygen in a river or lake if domestic
wastewater is discharged without proper treatment.
✔✔Anaerobic bacteria - ✔✔Will dominate a natural body of water that lacks dissolved
oxygen.
✔✔Secondary treatment - ✔✔Defined as consistently producing an effluent that
contains no more than 30 mg/L BOD and 30 mg/L Suspended Solids based on a 30-day
average.
✔✔Clean Water Act - ✔✔Requires WWTPs to achieve greater than or equal to 85%
removal of TSS and BOD.
✔✔Grab Sample - ✔✔A sample collected by the operator at a specific point in the
treatment process at a specific time.
✔✔Composite Sample - ✔✔A sample in which a series of grab samples are combined
during a 24 hour period.
✔✔Continuous Sample - ✔✔Used by online instrumentation to monitor parameters
typically collected by a grab sample.
✔✔Sample Preservation - ✔✔Stopping the chemical and/or biological degradation of a
sample by adding a chemical or lowering the temperature to about 4°C.
✔✔Chain of Custody - ✔✔A legal document providing a history of each person involved
in the handling of a sample from collection through final analysis.
✔✔Beaker - ✔✔Used for weighing and mixing chemicals, not for measuring liquid
volume.
✔✔Graduated Cylinder - ✔✔Used to quickly measure liquid volume, less accurate than
a pipette but more accurate than a beaker.
✔✔Pipette - ✔✔Used to accurately measure small volumes of liquid.
✔✔Buret - ✔✔Used for titrating chemical reagents and accurately measuring the
amount of titrant used.
✔✔Volumetric Flask - ✔✔Designed to accurately measure a fixed volume of liquid when
filled to the calibrated line.
, ✔✔Settleometer - ✔✔Used for determining the 30 minute settled sludge volume on a
mixed liquor sample.
✔✔Imhoff Cone - ✔✔The Imhoff cone is used to determine the settleable solids
contained in 1 liter of wastewater.
✔✔Composite Sample - ✔✔The appropriate type of sample for pH, dissolved oxygen
and chlorine residual.
✔✔Types of Composite Samples - ✔✔There are two types of composite samples which
are time-based and flow-proportional.
✔✔Continuous Samples - ✔✔Continuous samples are used by online instrumentation
to monitor parameters that would typically be collected by a grab sample.
✔✔Compliance Sample Points - ✔✔Compliance sample points are determined by the
primacy agency while process control sample points are determined by treatment plant
staff.
✔✔Sample Preservation with Acid - ✔✔Preserving samples with acid results in a
sample pH less than 2 pH units.
✔✔Cooling for Sample Preservation - ✔✔When cooling is used for sample preservation,
the sample should be stored at 4°C plus or minus 2 degrees.
✔✔Coliform Samples - ✔✔Coliform samples should be collected in 125 mL, sterile
sample bottles containing sodium thiosulfate to neutralize the chlorine residual.
✔✔Chain of Custody Form - ✔✔Samples collected for regulatory purposes and sent to
an outside laboratory for analysis must have a completed chain of custody form.
✔✔BOD Test Duration - ✔✔The BOD test takes 5 days to complete.
✔✔Lab Analysis Timing - ✔✔Lab analysis of pH, temperature and dissolved oxygen
should be performed within 15 minutes of samples collection since they can change
rapidly once collected.
✔✔pH Buffers for Calibration - ✔✔pH buffers used for pH meter calibration should
bracket the expected pH and be at least 2 pH units apart.
✔✔Dissolved Oxygen Determination - ✔✔Dissolved oxygen can be determined by the
Azide modification of the Winkler titration method.
QUESTIONS AND SOLUTIONS RATED A+
✔✔Hydrogen sulfide - ✔✔A dangerous byproduct of organic material decomposition
that increases with biological activity.
✔✔COD - ✔✔Chemical Oxygen Demand, typically ranging between 200 and 600 mg/L
in raw wastewater.
✔✔BOD:COD relationship - ✔✔The typical relationship between BOD and COD is 0.5:1
for raw wastewater.
✔✔Dissolved oxygen - ✔✔The amount of oxygen that can be maintained in water,
which decreases as water temperature increases.
✔✔CBOD test - ✔✔A test that measures carbonaceous BOD in biological process
effluent water, requiring a nitrification inhibitor.
✔✔Viruses in wastewater - ✔✔Viruses do not increase in number while in wastewater
as they require a host cell to reproduce.
✔✔Total Solids - ✔✔A term used to describe all solids contained within wastewater.
✔✔Ammonia levels in primary clarifier - ✔✔Increasing ammonia levels indicate a septic
condition in the primary sludge.
✔✔Storm events - ✔✔Commonly cause large amounts of sand, gravel, and grit to enter
the treatment plant.
✔✔Combined wastewater collection system - ✔✔A system that carries both sanitary
wastewater and stormwater runoff.
✔✔Total solids concentration - ✔✔In most wastewater, it is approximately 0.1%.
✔✔Suspended solids - ✔✔Approximately 30% of the total solids in wastewater are
characterized as suspended solids.
✔✔Dissolved solids - ✔✔Approximately 70% of the total solids in wastewater are
characterized as dissolved solids.
✔✔Septic conditions - ✔✔Caused by a lack of dissolved oxygen and the presence of
anaerobic bacteria.
✔✔Floatable scum - ✔✔Usually removed from wastewater in the primary clarifier.
,✔✔Aerobic bacteria - ✔✔Will deplete the dissolved oxygen in a river or lake if domestic
wastewater is discharged without proper treatment.
✔✔Anaerobic bacteria - ✔✔Will dominate a natural body of water that lacks dissolved
oxygen.
✔✔Secondary treatment - ✔✔Defined as consistently producing an effluent that
contains no more than 30 mg/L BOD and 30 mg/L Suspended Solids based on a 30-day
average.
✔✔Clean Water Act - ✔✔Requires WWTPs to achieve greater than or equal to 85%
removal of TSS and BOD.
✔✔Grab Sample - ✔✔A sample collected by the operator at a specific point in the
treatment process at a specific time.
✔✔Composite Sample - ✔✔A sample in which a series of grab samples are combined
during a 24 hour period.
✔✔Continuous Sample - ✔✔Used by online instrumentation to monitor parameters
typically collected by a grab sample.
✔✔Sample Preservation - ✔✔Stopping the chemical and/or biological degradation of a
sample by adding a chemical or lowering the temperature to about 4°C.
✔✔Chain of Custody - ✔✔A legal document providing a history of each person involved
in the handling of a sample from collection through final analysis.
✔✔Beaker - ✔✔Used for weighing and mixing chemicals, not for measuring liquid
volume.
✔✔Graduated Cylinder - ✔✔Used to quickly measure liquid volume, less accurate than
a pipette but more accurate than a beaker.
✔✔Pipette - ✔✔Used to accurately measure small volumes of liquid.
✔✔Buret - ✔✔Used for titrating chemical reagents and accurately measuring the
amount of titrant used.
✔✔Volumetric Flask - ✔✔Designed to accurately measure a fixed volume of liquid when
filled to the calibrated line.
, ✔✔Settleometer - ✔✔Used for determining the 30 minute settled sludge volume on a
mixed liquor sample.
✔✔Imhoff Cone - ✔✔The Imhoff cone is used to determine the settleable solids
contained in 1 liter of wastewater.
✔✔Composite Sample - ✔✔The appropriate type of sample for pH, dissolved oxygen
and chlorine residual.
✔✔Types of Composite Samples - ✔✔There are two types of composite samples which
are time-based and flow-proportional.
✔✔Continuous Samples - ✔✔Continuous samples are used by online instrumentation
to monitor parameters that would typically be collected by a grab sample.
✔✔Compliance Sample Points - ✔✔Compliance sample points are determined by the
primacy agency while process control sample points are determined by treatment plant
staff.
✔✔Sample Preservation with Acid - ✔✔Preserving samples with acid results in a
sample pH less than 2 pH units.
✔✔Cooling for Sample Preservation - ✔✔When cooling is used for sample preservation,
the sample should be stored at 4°C plus or minus 2 degrees.
✔✔Coliform Samples - ✔✔Coliform samples should be collected in 125 mL, sterile
sample bottles containing sodium thiosulfate to neutralize the chlorine residual.
✔✔Chain of Custody Form - ✔✔Samples collected for regulatory purposes and sent to
an outside laboratory for analysis must have a completed chain of custody form.
✔✔BOD Test Duration - ✔✔The BOD test takes 5 days to complete.
✔✔Lab Analysis Timing - ✔✔Lab analysis of pH, temperature and dissolved oxygen
should be performed within 15 minutes of samples collection since they can change
rapidly once collected.
✔✔pH Buffers for Calibration - ✔✔pH buffers used for pH meter calibration should
bracket the expected pH and be at least 2 pH units apart.
✔✔Dissolved Oxygen Determination - ✔✔Dissolved oxygen can be determined by the
Azide modification of the Winkler titration method.
