Wastewater Treatment Overview

The correct order of major treatment stages in a conventional activated-sludge plant is:

Bar screening is part of which stage?

Grit is removed at the:

The final treatment step before discharge to receiving water is usually:

The main purpose of preliminary treatment is to:

Return activated sludge (RAS) is returned from the secondary clarifier to the:

Waste activated sludge (WAS) is normally routed to:

An 'influent' is best described as:

In a conventional plant, where does effluent filtration (tertiary) usually fit?

Anaerobic digestion belongs to which side of the plant?

Which unit directly precedes the aeration tank in a conventional activated-sludge plant?

Scum and grease are skimmed from the surface of the:

Which is NOT a physical/chemical treatment step?

The headworks is best described as the plant's:

BOD stands for which of the following and what defines the standard test?

The BOD5 test is incubated under which conditions?

Ultimate BOD (BODu) compared to BOD5 is:

Carbonaceous BOD (CBOD) differs from total BOD because the CBOD bottle contains:

A BOD5 result is generally considered valid only when:

High influent BOD most directly indicates:

BOD5 is reported in which units?

Why is 'seed' sometimes added to BOD bottles?

A toxic influent that kills the BOD seed would most likely cause:

Compared to the BOD test, the COD test is:

For a given sample, COD is generally:

A high COD-to-BOD ratio in an influent typically signals:

A typical COD/BOD ratio for municipal wastewater is roughly:

Which test does NOT rely on a microbial population?

TOD (Total Oxygen Demand) measures:

TSS is the abbreviation for:

TSS is analyzed using which filter?

Volatile suspended solids (VSS) approximates the:

Fixed (non-volatile) suspended solids are mostly:

Total Solids (TS) equal which combination?

Settleable solids are most often reported in which units?

TDS measures the solids that:

In mixed liquor, the ratio MLVSS / MLSS is typically about:

Turbidity is most commonly measured in:

On the pH scale, a neutral solution at 25 °C reads approximately:

A solution with pH 5 is:

A solution with pH 9 is:

The pH scale commonly runs from:

Moving from pH 7 to pH 5 means the hydrogen-ion concentration changes by a factor of:

Alkalinity in wastewater is best described as the water's:

The dominant form of alkalinity in typical domestic wastewater is:

Nitrification affects alkalinity by:

Typical target dissolved oxygen in an aeration tank is about:

Dissolved oxygen is most commonly measured with:

Persistently low DO in an aeration tank most commonly promotes:

Biological treatment is generally inhibited when pH falls outside approximately:

Alkalinity is valuable in the aeration tank because it:

Most NPDES effluent permits restrict pH to a range of about:

Nitrification in an activated-sludge plant slows markedly below about:

A rough rule is that biological reaction rate changes by roughly a factor of ~2 for every:

A standard mesophilic anaerobic digester is held near:

As water temperature rises, the saturation concentration of dissolved oxygen:

Cold influent conditions most directly require operators to:

Which stage physically settles suspended solids and removes a portion of BOD before any biological step?

Primary treatment most effectively removes which pair?

Primary clarifiers do NOT significantly remove:

Typical primary clarifier detention time is about:

Primary sludge is most commonly pumped to:

Floatables (FOG and scum) are removed from primary clarifiers by:

Compared with no primary treatment, adding primary settling mainly:

The primary purpose of secondary (biological) treatment is to remove:

Which process is a common form of secondary treatment?

In secondary treatment, microbes convert dissolved organics mainly into:

The secondary clarifier's main job is to:

Nitrification occurs in the secondary system and converts:

Typical overall BOD removal for a conventional primary + activated-sludge plant is about:

Extended-aeration activated sludge generally operates in which growth phase?

Which is NOT a secondary (biological) process?

Tertiary treatment is best described as:

Effluent filtration (a tertiary step) primarily removes:

Chemical phosphorus removal is usually accomplished by adding:

Enhanced biological phosphorus removal (EBPR) relies on:

UV disinfection inactivates pathogens mainly by:

Chlorinated effluent is typically dechlorinated before discharge using:

Disinfection CT is best described as:

Which is NOT a common disinfection method?

Membrane bioreactors (MBR) combine which two functions?

The main purpose of sludge thickening is to:

Sludge stabilization is most commonly achieved by:

Common mechanical dewatering devices include:

A dewatered sludge 'cake' is typically about:

Final biosolids destinations include all EXCEPT:

Class A vs Class B biosolids differ mainly in:

A grab sample is best defined as:

A 24-hour composite sample is typically built from:

Which parameter is BEST measured by a grab sample analyzed immediately?

BOD and TSS compliance samples are usually taken as:

Nutrient samples (ammonia, nitrate, phosphorus) are commonly preserved by:

A chain-of-custody form primarily documents:

Every analytical parameter has:

NPDES is best defined as:

On monthly reports, DMR stands for:

An SSO is most commonly a:

Conventional municipal NPDES permits commonly limit all EXCEPT:

Typical effluent pH range in an NPDES permit is approximately:

Monitoring data on the DMR is most often reported:

An MS4 permit governs:

Hydrogen sulfide becomes immediately dangerous to life and health (IDLH) at about:

Acceptable oxygen for confined-space entry is approximately:

A permit-required confined space entry requires:

LOTO is best described as:

For an IDLH atmosphere (e.g., H₂S, low O₂), required respiratory protection is:

The most frequent cause of injury at wastewater plants is:

COD stands for:

TDS stands for:

MLSS stands for:

RAS stands for:

WAS stands for:

SVI stands for:

F/M stands for:

MCRT (SRT) stands for:

HRT stands for:

SCADA stands for:

ORP stands for:

BNR stands for:

EBPR stands for:

MBR stands for:

RBC stands for:

SBR stands for:

UVT in UV disinfection refers to:

NTU is the unit for:

SCADA is most valuable to an operator for:

Which conversion factor converts concentration (mg/L) × flow (MGD) into pounds per day?

How many gallons are in one cubic foot of water?

One cubic foot of water weighs about:

One gallon of water weighs about:

Which value is closest to π used for quick plant calculations?

The standard formula relating flow, area, and velocity is:

A parameter that indicates septicity (anaerobic conditions) in a sample is:

Which measurement best reflects how 'clear' a final effluent is?

An operator's first responsibility under all operating decisions is: