Below the Surface: Measuring Organic Sum Parameters in Water

Related Vendors

Another issue is toxicity: Although the nitrification inhibition test has not seen much consideration, its results are remarkable: Studies demonstrated the significantly lower EC20 and EC50 values of the determined substances in comparison to tests with luminescent bacteria (the common biomass for online toxicity tests). For Cyanide for example, the EC50 value in the nitrification respiration inhibition test is ≤ 0.15mg/l compared to 8.5 mg/l with luminescent bacteria.

Testing Toxicity Online

Important criteria for online toxicity measurements are an easy handling as well as a fast determination. Latest innovations allow to constantly grow nitrifying bacteria in a fermenter within the analyzer, providing enough biomass at any time. A small amount of this self–sustaining biomass is mixed with the sample in the measuring cell where subsequently the actual respiration measurement takes place by monitoring the oxygen consumption. This method stands out through its high reproducibility, as the measuring cell is flushed with a cleaning solution after each measurement, avoiding any cross contamination or memory effects of previous samples.

A Proven Alternative

Based on the above mentioned criteria, the best choice for sum parameter monitoring of organic matter in water are high-temperature TOC and TOD analyzers. The online determination of TOD is a clean and fast method to define the oxygen demand of a water sample that is both relatively environmentally friendly and a suitable alternative for COD measurements.

Additionally, innovative online toxicity analyzers offer a reliable and fast detection of pollutants: Using highly sensitive nitrifiers as test organisms, these units show, how toxic substances affect the biology of public waters. In several international project these innovative solutions are used to monitor reliably the condition of rivers and lakes.

* The author works for LAR Process Analysers.

(ID:42594995)