List of Organic Matter in Water, Nonspecific Tests

Organic Matter in Water, Nonspecific Tests

Test

Description

BOD

Biochemical oxygen demand. Measures the ability of common bacteria to digest organic matter, usually in a 5-day incubation at 2O0C, by analyzing depletion of oxygen. This measures biodegradable organic matter. Expressed as O2.

CCE

Carbon-chloroform extract. Organics adsorbed on an activated carbon

cartridge are extracted from the carbon by chloroform. The extract

is weighed or further analyzed.

CAE

Carbon-alcohol extract. Organics adsorbed on an activated carbon

cartridge are extracted from the carbon by ethyl alcohol. (This is

performed after the chloroform extraction of the same column.)

COD

Chemical oxygen demand. Measures the ability of hot chromic acid

solution to oxidize organic matter. This analyzes both

biodegradable and nonbiodegradable (refractory) organic matter.

Expressed as O2.

Color

Color. This is a rough measure of tannin, lignin, and other humic

matter in surface waters and certain wastes, such as kraft pulping

wastes. Reported in APHA units, related to platinum standard.

IDOD

Immediate dissolved oxygen demand. Measures the presence of strong reducing matter in wastes which would have an immediate

effect in reducing the oxygen level of receiving streams. Determined by measuring reduction in oxygen 1 5 min after dilution of sample with an O2-saturated water. Expressed as O2

LOI

Loss on ignition. In this determination, the water sample is first

evaporated to dryness, then weighed. The solids are then heated to

a dull red heat and reweighed. The difference in the two weights is

loss on ignition. The firing step burns off organic matter, but it also

affects mineral composition, as in the breakdown of carbonates to

oxides, so the loss is not all organic.

O2 consumed

Oxygen consumed from permanganate. Measures the susceptibility of

organic matter in sample to oxidation by KMnO4. Not as strongly

oxidizing as chromic acid. Preceded the COD test and still a useful

control test. Reported as O2.

Solvent

Extractables. Measures the organic matter directly extractable from

extractables

water, usually using hexane, although CCl4 and CHCl3 are also

used.

TOC

Total organic carbon. Measures the CO2 produced from organics when a water sample is atomized into a combustion chamber.

The CO2 equivalent to the alkalinity may be removed first, or this equivalent may be subtracted from the total CO2 to determine organic carbon reported as C

 

Author: T.P.Sivanandan


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