Biochemical Oxygen Demand Quiz

The amount of dissolved oxygen needed by aerobic microorganisms to break down organic matter in water.

A two-stage process: Stage I oxidizes simple and complex organic compounds, while Stage II (after 6-10 days) includes nitrification (oxidizing nitrogen compounds).

A technique used to measure dissolved oxygen levels in water samples.

Reducing the concentration of a sample by adding a solvent, typically water.

Allowing a water sample to sit and undergo biological processes (usually for 5 days).

A process where ammonia is oxidized into nitrites then nitrates by specialized aerobic bacteria.

The amount of oxygen dissolved in a water sample, a key measurement in water quality.

The ratio comparing the final volume of a diluted solution to the initial volume of the concentrated solution.

Biochemical Oxygen Demand after 5 days, a measure of the amount of dissolved oxygen consumed by microorganisms in a water sample.

Biochemical Oxygen Demand after 7 days, a measure of the amount of dissolved oxygen consumed by microorganisms in a water sample

Dilution Water containing phosphate buffer, magnesium sulphate, calcium chloride, magnesium chloride, microorganisms that are saturated with oxygen and adjusted to pH 7.2

Ratio of dilution water to the original sample, commonly 1:5 or 1:10

Calculated using oxygen concentration in the sample before and after incubation with the dilution water.

The first of 2 dilution steps in a BOD measurement with a dilution ratio of typically 1:5 or 1:10

Second dilution step in a BOD measurement, twice as large as the first, with a dilution ratio.

500 ml is used for BOD procedure; 1000ml for calculations

Iron exists in two forms: Fe2+ (ferrous) and Fe3+ (ferric).

High DO levels favor Fe3+, while low DO levels favor Fe2+.

High concentrations of iron and manganese can affect taste, odor, and potentially cause pipeline blockage.

Metals dissolve from soil, rocks, and minerals when groundwater contacts them.

500 mL is often used when testing and analyzing chemical properties of a sample.

1000 mL is often used to calculate the amount of a parameter or substance present in the sample.

The process of reducing the concentration of a sample by adding dilution water.

Parameters measured, such as oxygen concentration, and amount of sodium thiosulfate used, can be measured (titrated) before and after incubation.

Groundwater iron reacts with atmospheric oxygen, changing from Fe2+ to Fe3+ (oxidation), and forming rust-colored deposits.

Measures iron concentration by adding reagents (hydroxylamine hydrochloride, acetate buffer, 1.10 phenanthroline) to a water sample then measuring the absorbance at 510nm with a spectrophotometer.

Measures manganese concentration by adding a special reagent (a mixture of HgSO4, HNO3, and AgNO3) to a water sample, heating, and measuring the absorbance at 525nm with a spectrophotometer.

The maximum acceptable concentration of iron in drinking water is 200 µg/L.

Detects sulphate concentration by adding a specific reagent ('A reagent') to a water sample, shaking and measuring the absorbance at 430nm using a spectrophotometer.