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Two-in-one UV analyser family for disinfection measures ammonia, nitrate, or COD in wastewater

Electro-Chemical Devices (ECD) has released a new single or dual parameter CA-6 UV family of spectroscopic analysers that can monitor any two selected parameters in separate measurement ranges for ammonia, nitrate, or chemical oxygen demand (COD 254 nm).


ECD’s CA-6 UV analyser family provides a highly accurate, reliable, and economical on-line sampling system that is designed with UV absorption sensor technology to monitor harmful pollutant parameter levels.

The analyser’s sensors are available in multiple parameter measurement ranges, including ammonia from 0-10mg/l or 0 to 1000mg/l, nitrate from 0-30mg/l, 0-100mg/l, or 0-250mg/l, and COD 254 nm from 0-200mg/l or 0-20,000mg/l.

Each model is available with either a single parameter or dual parameters in the factory pre-calibrated measurement ranges.

A single technician can complete the analysers’ installation process in 15 minutes by connecting the sample, waste, and cleaning solution (reagent) lines and powering up the device.

Accessing the chosen factory pre-calibrated parameter data or customising an analysis routine is easily done with user-friendly intuitive menus and a touch screen display.

Each parameter is analysed based on the measurement of UV absorption in the sample.

The absorbance of the solution or gas is measured through a quartz flow cell at a specific wavelength using a long-life Xenon lamp and photo detectors.

The absorbance level is directly related to the sample concentration according to Beer-Lambert’s Law, which correlates the attenuation of light to the properties of the material through which the light is traveling.

To measure ammonia, a reagent is added to the liquid sample and converts the ammonia to gas for measurement by the CA-6’s UV sensor with a fast Fourier transform algorithm that provides a measurement equivalent to the level of ammonia.

A water temperature probe performs automatic temperature compensation for high accuracy.

In measuring the nitrate found in turbid, organic-rich wastewater, the CA-6 UV’s advanced self-cleaning design relies on the strong absorption of UV light by the chromophore N-O, which again is according to Beer-Lambert’s Law.

Automatic internal linearization compensates for high concentrations of nitrate, while a second wavelength and detector compensates for dirty matter in the flow cell to ensure high accuracy and reliability.

For the measurement of COD 254 nm, the CA-6’s sensor detects UV light absorption by unsaturated organic molecules at the 254 nm wavelength.

COD 254 nm levels in river water and municipal wastewater are closely correlated to the permanganate and dichromate water standard methods.

Measurement is highly responsive, less than 10 seconds, and requires no reagents or calibration solutions.

Accuracy is 5% for the measurement of ammonia, nitrate, and COD with the CA-6 UV analyser, based on a sample temperature range of 0 to 80°C, but the sample must be liquid and not frozen.

Repeatability varies based on the parameter chosen and the single or dual parameter configuration, ranging from 0.15 to 3%. 

The CA-6 analyser is designed with four alarm relays, with a single 4-20mA analogue output included with 12-bit resolution.

RS232 communications are provided for data download to a CSV file, with an optional RS485 MODBUS communication module available.