2. Innovation / 3. Water & Environmental / Biochemical Oxygen Demand

New COD technology as a tool for fast BOD estimation

As well as offering a safer, faster method of COD analysis, the PeCOD system of COD analysis may also offer a fast method for BOD level estimation. This offers a fantastic tool for fast paced sites that cannot afford to wait the 5 or more days for traditional BOD results.

One wastewater treatment site in Guelph, Canada, has made the switch to PeCOD technology and has already seen the benefits in operational efficiency.

Unfortunately the PeCOD system is no longer available. You can click here to view our COD range.

The general manager Ian Culverwell commented; “Speed of results creates a more efficient process and really drives clean compliance which is critical for us”

Clean Harbors PeCOD system
The Clean Harbors team in Guelph, Canada, with their PeCOD system for COD analysis and BOD estimation

Industrial Waste Water Treatment

Clean Harbors offers services in the environmental, energy and industrial sectors throughout North America. These include a series of wastewater treatment facilities, which use chemical precipitation processes to remove heavy metals, suspended solids and organics from contaminated water, leaving it safe for discharge into standard sewerage systems.

The plant in Guelph, Canada, manages particularly large quantities of oily water and non-hazardous sludge from a range of industries, with approximately 37 million litres processed each year on site.

Meeting Discharge Consents

Discharge of treated waste from the plant is controlled by a BOD (Biological Oxygen Demand) cap, which batches may not exceed.

A standard BOD test includes a 5 day incubation period. As with many industrial sites, Clean Harbors did not have the holding capacity to store batches of waste while waiting for these results.

Faster Results

The measurement of COD was implemented on site as an indicator of BOD.

The traditional dichromate method of COD analysis (CODcr) using COD vials offered a good time saving versus BOD analysis, but the results can still take up to 3 hours to complete.

There was also concern about performing the tests due to the potentially toxic chemicals present in the COD vials – mercury, potassium dicrhomate and concentrated sulphuric acid.

On Site Trials

After hearing about PeCOD technology the site began a trial to see if the system could resolve their problem, and to see;

  1. How do PeCOD results for COD compare to CODcr results?
  2. How do PeCOD results for COD relate to BOD results?
  3. Can the continuous online monitoring speed up processes on the plant?

During the trial samples from a range of batches were tested by PeCOD, CODcr and BOD analysis at an accredited laboratory.

Positive Results

Over a range of samples the correlation between PeCOD and BOD results was stronger than the correlation between CODcr and BOD – meaning PeCOD is better as a BOD indicator.


PeCOD results correlate well with BOD results
The correlation between PeCOD and BOD results was strong with an R2 value of 0.8 – stronger than the correlation of traditional CODcr method with BOD results.

As well as the successful technical results, the management team were impressed with the improvements in speed and efficiency.

General Manager Ian Culverwell commented; “We run a 16-hour per day operation, so retention time on the majority of our waste is less than 24 hours. Timing on the PeCOD is critical for us. With the PeCOD we can get results in 15 minutes, allowing us to turn over our processing tanks much quicker, and process more waste without increasing the size of our tank farm.”

It is hoped that the PeCOD technology can be used in the same way on other sites, allowing huge time savings that in turn relate to cost and environmental savings too.

Unfortunately the PeCOD system is no longer available. You can click here to view our COD range.

For more information, or to discuss how PeCOD could be used on your site, just contact us;