An instrument for fast and sensitive detection of toxic substances in water

The bbe Algae Toximeter continuously analyses water for the presence of toxic substances. Standardized algae are added to the water sample and the instrument detects the photosynthetic activity of the chlorophyll. If the algae are damaged, for example by herbicides, a reduction in algae activity and indirectly in oxygen production is caused and an alarm is activated after a pre-defined threshold has been exceeded.

The bbe Algae Toximeter also serves as a measuring instrument for the precise determination of algae concentration in the water.  This is done by excitation with colored LEDs. It enables the calculation of the content of green algae, blue-green algae, brown algae (diatoms and dinoflagellates) and cryptophyceae. Additionally, an algae group differentiation applied to the sample water offers the possibility of the quantitative allocation to different spectral algae classes. This measurement principle corresponds to that of bbe's tried and tested AlgaeOnlineAnalyser and AlgaeLabAnalyser.

The bbe Algae Toximeter works with a double test loop, short measuring intervals and a PC for online data analysis, which permits a high temporal resolution of the water to be monitored. The instrument has an automatic cleaning device and a low level of maintenance.

Principles of the bbe Algae Toximeter

The cultivation of the algae takes place in a fermenter, which is regulated "turbidostatically" by a second fluorescence measurement. This regulation ensures that the algae concentration and their activity are maintained.

The measurement procedure requires the water samples be almost continually pumped into the bbe Algae Toximeter, in which the concentration and the activity of the naturally occurring algae are determined. A precisely defined amount of algae from the fermenter is then added to the measuring chamber by way of a loop. The activity of the added algae remains constant as long as no toxic substances are present. If any toxic substance is present, its interaction with the photosynthesis centre leads to an inhibition of algae activity. The dimensions of the inhibition can be estimated by comparing the algal activity with and without water sample.

After each measurement, the measuring chamber is automatically cleaned by a piston. This prevents the growth of algae and biofilms within the measuring chamber.

Applications:

• drinking water supply
• dam monitoring
• waterway analysis and assessment
• general environmental assessment
• intake monitoring
• chemical analysis
• limnological work
• research and education

Brochures:

• bbe Algae Toximeter

Measurements:

• direct chlorophyll fluorescence:
  corresponds to wet-chemical chlorophyll analysis
• active chlorophyll fluorescence in the sample (Genty method):
  determines the percentage of active chlorophyll under illumination and serves as a toxicity measurement
• differentiation of fluorometric algae classes:
  to simultaneously determine the content of chlorophyll according to green algae, blue-green algae, brown algae (diatoms and dinoflagellates) and cryptophyceae
• transmission:
  takes place automatically during each analysis and if necessary, can be used to compensate the influence of substances which cause turbidity.

The bbe Toximeter:

• is highly sensitive with regard to the detection of herbicides and their by-products
• is sensitive to a wide range of toxic substances
• has controlled independent cultivation of algae
• provides cultivation control due to active chlorophyll measurement
• reduces dosage error due to aging tubes
• has an anti-fouling system due to automatic cleaning of the measuring unit
• has auto start function after power failure
• is certified - CE-sign

The Software:

The database software is used to record and analyze the data. The most important features are...

• saving of data and parameters at any time
• graphic display of all measurement values
• online display in LAN
• calibration of the instrument
• parameterization of the measurement
• data export to EXCEL and to text files
• print function
• subsequent recalibration of algae classes

Specifications of the Algae Toximeter

• inhibition of photosynthesis
• total chlorophyll [µg Chl-a/l]
• concentration of green algae [µg Chl-a/l]
• concentration of blue algae [µg Chl-a/l]
• concentration of diatoms [µg Chl-a/l]
• concentration of cryptomonades [µg Chl-a/l]
• yellow substances
• photosynthetic activity (Genty)
• transmission (at 5 wavelengths)