The parameter Chemical Oxygen Demand (COD) is of special importance in water analysis. In contrast to common cuvette tests, the COD can be measured in an environmentally-friendly way using high-temperature combustion technology.
COD is one of the most important sum parameters in water analysis as it provides a reference for organic loading in wastewater.
There are various methods currently available for laboratory use, such as dichromate reflux and cuvette digestion.
However, the wet chemical potassium dichromate methods require the use of hazardous and dangerous chemicals that often become an OH&S concern, while cuvette tests may become costly for high-sample volumes due to non-automated procedures.
LAR’s new QuickCODlab utilises the thermal oxidation method. A precision sample volume is injected directly into the reactor.
Following injection, the sample is fully oxidized by the non-catalytic high-temperature combustion technology at 1,200°C.
This method guarantees the complete oxidation of all organic substances. Compared to the cuvette test, no interferences with chlorides occur, which is preferable when rapid results are required.
Testing in action
As one of the major issues to address in the AKIZ project, wastewater from industrial zone Tra Noc in Can Tho City, Vietnam, contained pollutants in dissolved, colloidal and particulate forms from seafood processing facilities in the area. This resulted in high amounts of nitrogen compounds and a varying composition of organic matter.
As part of this project, comparative measurements from wastewater were taken using both common cuvette tests and the new QuickCODlab.
The benefits of the new QuickCODlab were found to include:
- Fast analysis of oxygen demand in three minutes
- No chemicals required
- Practise-proven oxidation technique: high temperature combustion at 1,200°C
- Total oxygen demand (TOD) detection according to ASTM
Wastewater in a fruit and vegetable processing plant
When processing fruit and vegetable waste such as seeds and skin, as well as residues of processed products, food additives and salts are produced. Therefore, the composition of wastewater is very heterogeneous.
Such samples have to be pre-treated prior to measurement in order to ensure that particles within the sample are included.
Below are the results of the high temperature COD method comparable to the cuvette tests.
Sample High Temperature COD COD cuvette test Deviation
FW-1 2,076 mg/l 1,901 mg/l 8.4%
FW-2 667 mg/l 698 mg/l 4.6%
FW-3 9,030 mg/l 8,708 mg/l 3.6%
FW-4 1,098 mg/l 1,008 mg/l 8.2%
Deviation of the results demonstrate high level of oxidation at 1,200°C for samples with high amount of suspended matter, and shows that it detects the oxygen demand completely and reliably.
Wastewater in a beer bottling facility
Wastewater from brewing and bottling facilities can contain a myriad range of contaminants, including organics, sugars, paper fragments and high salt levels.
QuickCODlab analyser can process alkaline wastewater with concentrations of up to 12g/L aluminium and 20g/L sodium hydroxide (used to remove bottle labels).
The thermal oxidation technology, at 1200°C, allows the high salt concentrations to travel through reactor, discharging with the condensate.
Sample High Temperature COD COD cuvette test Deviation
WSB-1 4,480 mg/l 4,314 mg/l 3.7%
WSB-2 3,412 mg/l 3,359 mg/l 1.6%
WSB-3 3,810 mg/l 3,948 mg/l 3.6%
The above table shows the LAR laboratory analyser detected the COD concentrations in line with common cuvette tests.
After two years of implementation in the AKIZ Vietnam pilot facility for recovery of valuable materials by use of membrane filtration, QuickCODlab has proved it has many advantages in comparison to cuvette tests for a range of wastewater compositions.
Measurement results were available within two to four minutes based on the application and because the QuickCODlab analyser doesn’t require any chemicals, it prevented contamination of the environment, while being competitively cost-effective.
This partner content is brought to you by ThermoFisher. For more information, visit thermofisher.com.au/QuickCODlab.
