BNR & Nutrient Removal

Total Kjeldahl Nitrogen (TKN) is the sum of:

In wastewater, 'ammonia nitrogen' usually refers to:

The dominant ammonia species at typical wastewater pH (~7–7.5) is:

Which nitrogen form is most toxic to fish?

Oxidized nitrogen (NOx) usually means:

Nitrite is an intermediate in which process?

Organic nitrogen in raw wastewater comes mostly from:

Ammonification in the sewer/primary refers to:

Nitrification in an activated-sludge plant is best described as:

The two key nitrifying organism groups are:

Nitrifiers are best classified as:

Compared with carbon-oxidizing heterotrophs, nitrifiers generally:

Nitrification requires which environmental condition most directly?

Nitrification produces:

Free ammonia inhibition of Nitrobacter can cause:

A loss of nitrification is often signalled first by:

The minimum SRT needed for nitrification mainly depends on:

Why is a residual DO higher than ~1 mg/L common in nitrifying plants?

Materials toxic to nitrifiers include (commonly):

If the plant nitrifies in summer but loses nitrification in winter, the action is usually to:

Nitrification consumes approximately how much oxygen per mg of NH₃–N converted to NO₃⁻?

Nitrification consumes approximately how much alkalinity (as CaCO₃) per mg NH₃–N oxidized?

Denitrification recovers how much oxygen equivalent per mg NO₃⁻–N reduced?

If a plant nitrifies fully (10 mg/L NH₃–N in, near zero out) without denitrification, the net alkalinity consumed is about:

Alkalinity should be checked during nitrification because:

Common chemicals to supplement alkalinity include:

The minimum DO below which nitrification slows markedly is around:

Adding too much alkalinity to maintain nitrification at cold temperature would mainly:

If a plant has high influent alkalinity but is still losing nitrification, the likely non-alkalinity cause is:

Oxygen from nitrification recovery (denitrification) appears as:

Nitrifiers are strongly affected by temperature; cold conditions require:

Low pH (<~6) affects nitrification by:

Nitrifier growth is favored by:

A sudden influent pH drop is most likely to first affect:

Which is the most common seasonal nitrification problem?

Operators can detect early nitrification loss by trending:

Higher MLSS (longer SRT) is most often used in cold weather to:

When the plant nitrifies well but effluent nitrite (NO₂⁻) climbs, suspect:

Denitrification is best summarized by which reaction?

Denitrification requires which environment?

Why is denitrification valuable beyond compliance?

What gas is the end product of full denitrification?

Denitrification generally:

The carbon source for conventional (post-) denitrification in the main train is usually:

When influent BOD is insufficient for full denitrification, the operator typically adds:

An internal mixed-liquor recycle (nitrate recycle) in an A²O process sends nitrate-rich mixed liquor to:

Free dissolved oxygen in the anoxic zone:

Low ORP (≈ −100 to +50 mV) most closely indicates:

Methanol-fed denitrification commonly requires a C:N ratio (methanol:NO₃–N) of about:

Methanol feed should be paced to:

Denitrification with too little carbon produces:

An ORP 'nitrate knee' on the ORP profile indicates:

Post-anoxic (after aerobic) denitrification without mixing risks:

Too much denitrification caused by overfeeding carbon can lead to:

An unexpected effluent BOD rise after starting methanol dosing usually means:

Hydraulic shortcutting in an anoxic zone typically results in:

EBPR stands for:

Which organisms drive EBPR?

EBPR requires which zone sequence in the main train?

In the anaerobic zone, Poly-P bacteria:

In the aerobic zone, Poly-P bacteria:

Phosphorus actually leaves the EBPR plant mainly via:

EBPR needs which carbon source most?

How do plants increase VFAs for EBPR when influent VFAs are low?

EBPR is most directly inhibited in the anaerobic zone by:

Poly-P bacteria store carbon intracellularly as:

A common EBPR failure mode is:

GAOs are best controlled by:

Secondary (anaerobic) phosphorus release in a clarifier/digester results in:

Signs EBPR is working include:

Chemical P removal is often used to:

EBPR is particularly attractive relative to chemical P removal because:

Why does encouraging EBPR require limiting nitrate recycle into the anaerobic zone?

When EBPR breaks down, total phosphorus (TP) usually:

Chemical phosphorus removal primarily uses:

The dose of metal salt for P removal is typically expressed as:

Chemical P removal produces:

Adding alum/ferric affects alkalinity and pH by:

Simultaneous precipitation in activated sludge means:

Pre-precipitation in primary clarifiers removes:

Which best describes post-precipitation?

Chemical P removal benefits include:

A²O stands for:

In an A²O process, the internal recycle returns:

RAS in an A²O process is normally returned to:

The 4-stage Bardenpho process adds:

A 5-stage Bardenpho adds which zone at the front?

A modified A²O / VIP process differs mainly by:

SBR can perform BNR by:

Oxidation ditches with anoxic zones can perform BNR by:

Which configuration best suits a stringent very-low TN + TP permit?

Membrane bioreactor (MBR) BNR advantages include:

Post-denitrification filters (e.g., denite) are used to:

An MBR + EBPR + polishing chemical step balances:

Oxidation-Reduction Potential (ORP) is most useful in BNR to:

Typical ORP for a healthy anaerobic (EBPR) zone is about:

Which lab results are most essential for nutrient monitoring?

Total Nitrogen (TN) is best calculated as:

Monitoring orthophosphate (ortho-P) versus total phosphorus (TP) tells you:

Online nutrient analyzers need:

A rising effluent NO₃–N with normal NH₃ usually indicates:

Operators use mass balances to:

An alkalinity mass check during BNR confirms whether:

Recommended trend for BNR control includes all EXCEPT:

Anammox is best used:

ANAMMOX (anammox) converts ammonia and:

Side-stream treatment reduces main-plant load by:

Struvite (MgNH₄PO₄·6H₂O) forms when:

Struvite can be intentionally recovered to:

Anaerobic digester centrate/filtrate often contains a 'spike' of:

Why can struvite damage equipment?

An operator seeing white crystal deposits on dewatering equipment first suspects:

Total Nitrogen (TN) compliance is best computed as:

A typical A²O internal nitrate recycle ratio (relative to influent flow) is about:

RAS return to the anaerobic zone should be managed to:

Anammox needs which ratio of substrates roughly?

ORP in a healthy aerobic zone is commonly about:

EBPR organism failure producing low anaerobic P release but still taking up P aerobically suggests:

Operating an anoxic zone cooler than design typically:

A viable EBPR 'release test' shows:

Carbon dosing with glycerin (vs methanol) typically needs attention to:

Recycle of anaerobic-digester centrate can spike the main process with:

Magnesium dosing or inhibition is used to control:

Alkalinity should be checked during denitrification because:

A common EBPR metric is the 'P released/C uptake' ratio; abnormal values suggest:

Cold-weather nitrate breakthrough (NO₃ high, NH₃ low) usually means:

A 'slug' of high-fat influent most directly risks EBPR by:

Favorable EBPR pH relationship (vs GAOs) means operators often:

An operator should suspect a VFA shortage when:

Sidestream nitritation/anammox is favored over mainstream because: