DescriptionCOD Analyser: CX3000 Series
The COD of effluent water is a critical parameter for environmental requirements, and one often checked by regulatory authorities. This fast and reliable on-line measuring system is ideal.
The method used is UV absorption; it requires no filtering, no reagents, no consumables and no dilution. To limit the quantity of lab analysis, samples are only taken when measurements exceed a critical value.
Application is ideal for river water / waste water:
The measurement principle is based on the absorption of UV light by unsaturated organic molecules at 254 nm, according to the Beer-Lambert law.
Generally, real-life water samples are amix of many different compounds. Since we work with a single absorption co-efficient, the instrument must be calibrated using a laboratory COD measurement before use.The effect of the calibration is to assign an average absorption co-efficient for the water matrix to be measured. This assumes that the ratio of the different compounds in the sample remains approximately constant to assume a good correlation with the laboratory value.
UV absorption can be considered as an alternative method for COD when fast, reliable and inexpensive measurements with very low maintenance are required.
Results are excellent for river water or urban wastewater, while you may need to experiment for industrial waste water.
Turbidity, suspended solids or dirt on the flow cell are automatically compensated for by a differential measurement with a second detector at a reference wavelength.
This standard is in accordance with DIN38404-C3 standard and can be considered as an alternative to the AFNOR XPT90-210 standard.
Several ranges are available according to the flow cell installed. River-water applications usually require low ranges, while urban waste-water usually requires high ranges.
For a specific effluent, the ratio COD/UV can be entered according to laboratory COD measurements.
Once daily, a low cost cleaning solution (10% Sulphuric Acid) automatically cleans the flow cell. An auto-zero is performed at the same time. The 5-litre container (standard accessory) provided hols sufficient soltution for about 3 weeks. An alarm is generated when the container becomes empty.
The operating cost is limited to the refilling of the 5-litre cleaning solution container every 2 weeks with 10% Sulphuric acid. For effluent measurements, you can normally use distilled water instead.
Operating costs (including labour) are about $100 per year.