The clean COD determination in the laboratory. Chemical-free
Chemical oxygen demand (COD) describes the amount of oxygen that is needed to chemically oxidise organic compounds in water, using an (often environmentally dubious) oxidant. The aim is to determine the demand for oxygen, which is primarily required to oxidise organic matter. This oxygen demand is relevant for the\ planning, control and cleaning efficiency of waste water treatment plants, as well as a basis for the calculation of sewage charges. The standard potassium dichromate method (DIN 38409 H41-H44) dominates the market. It is also available in a modified form as cuvette tests (DIN ISO 15705:2003). Here, potassium dichromate is used as an oxidising agent, silver sulphate as a catalyst, as well as sulphuric acid. Mercuric chloride is also used to mask chloride interferences. This risky chemical cocktail is heated after the aqueous sample has been added, and then simmered for approx. two hours. The oxygen demand is calculated from the concentration of residual dichromate.
The COD procedure from LAR Process Analysers AG is based on the thermal oxidation of the sample at 1,200°C, with subsequent detection of the oxygen consumption. This method (ASTM D6238- 98) has been employed hundreds of times in the field of online monitoring and has been specially developed for use in the laboratory. The crucial point with QuickCODlab: The high-temperature procedure developed by LAR enables the reliable oxidization of all the organic compounds in the sample at a temperature of 1,200°C. The procedure does not need any catalysts or other hazardous or corrosive reagents. Furthermore, the measurement results are free of chloride interference due to the unique process management. The homogenized sample is injected directly into the reactor (Fig.1), where it is completely oxidised and accurately analysed with an O2 detector. Fast. Clean. Precise. Determining the COD within minutes. The QuickCODlab ensures a high operational reliability and is easy to use. The measured values are output directly to a standard computer and can be quickly and easily processed. The COD measurement is available in just a few minutes.
COD measurement is accomplished in less than 3 minutes. Thus, 3 replication measurements per sample can be determined within just 10 minutes. The QuickCODlab offers enormous time and cost savings in comparison to standard procedures.
ADVANTAGES & FEATURES
- Accurate determination of the real COD
- Measurements in just three minutes
- Extensive measuring ranges
- Proven thermal oxidation principle at 1,200°C
- No catalyst needed
- Reliable measurement without reagents
- Easy to operate
- Predefined injection volumes
- Excellent chloride acceptance
- Very low measurement costs
- High operational reliability
- Very low operating and maintenance costs