On-line analysis of COD by the Standard Method

The Applikon Process Analyser ADI 2040 mimics the COD (Cr) test and delivers its results at regular time intervals.

Law enforcement on staying in compliance with environmental legislation demands COD levels to be within specification, and accurately chemically analysed.

The accurate and true value of COD to both law enforcing bodies and "polluters" is of vital importance from the perspective of control and avoiding fines.

Hence the requirement, for having analysis done frequently, and for the potential "polluting party" also quickly, in order to stay in close touch with the water quality and treatment process.

The problem however, using the normalised and widely accepted method is, that it takes 2 hours to run the analysis and it releases a nasty waste (chromium).

Attempts have been made to solve these problems: e.g: analysers using OH radicals, either generated by an electrode or by ozone, these did produce quick results but were very unreliable because the vast majority of organic matter can not be oxydised within the short life time of the OH radicals.

Another option was to use UV spectrophotometry by the normalised method DIN 38404.

Although basically suitable in many cases, the correlation between the UV and the standard method is not general, since each component has its own absorption characteristics.

Only for individual processes one can obtain correlation, based on experience.

The answer is to have an analytical system which utilises a quick test and verifies itself against the standard (DIN 38409- 44, EPA 410.4).

This is a realistic option with the Applikon Process Analyzer ADI 2040, which truly mimics the COD (Cr) test.

It delivers its results at regular time intervals or upon "if-command," based on readings from its attached UV spectrophotometer.

The 2040 really offers the best of both worlds: continuously in touch by the UV photometer, backed by the standard test, but run only when off-limit.

Thus minimising reagent usage.

Besides its main duty to provide reliable results, the ADI 2040 may also compensate for chloride when present, thus omit- ting the need for masking agent (mercury).

On top of that, the ADI 2040 has room enough for other analyses and an automatic calibration.

In this way, just one 2040 will be the dependable basis for many of your environmental analyses.

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