Chemical Oxygen Demand (COD) Online

Chemical Oxygen Demand (COD)

Understanding Chemical Oxygen Demand (COD) and its Real-Time Measurement with UV254
Chemical Oxygen Demand (COD) is a crucial parameter used to assess the organic pollution level in water and wastewater. It quantifies the amount of oxygen required to chemically oxidize both biodegradable and non-biodegradable organic compounds present in the water. Monitoring COD is essential to evaluate the water's pollution potential and determine the effectiveness of treatment processes.

Traditional COD Measurement using Chemistry
Traditionally, COD measurement involves chemical methods like the dichromate reflux method or closed reflux colorimetric method. In these methods, the sample is chemically digested with a strong oxidizing agent, and the consumed oxygen is indirectly measured to determine the COD. While accurate, these methods are time-consuming, require skilled personnel, and involve the use of hazardous chemicals.

Real-Time COD Measurement with UV254
Advancements in technology have introduced a more efficient and real-time approach to measuring COD using UV254 spectroscopy. UV254 refers to the ultraviolet absorbance at a wavelength of 254 nanometres, which is particularly sensitive to aromatic and unsaturated organic compounds.

Benefits of UV254 for Real-Time COD Measurement

Speed and Real-Time Monitoring: UV254-based COD measurement offers real-time results, allowing immediate monitoring of changes in organic matter levels.

. Reduced Chemical Usage: UV254 measurement eliminates the need for hazardous chemicals, making it environmentally friendly and safer for operators.

Continuous Monitoring: UV254 spectroscopy enables continuous monitoring, providing a dynamic view of organic matter levels over time. Ease of Use: UV254 measurements are relatively easy to perform, and the equipment requires minimal maintenance.

COD Online Measurement


Multiple Measurements

UVT,UVA, IRT & indicative readings COD, TOC, BOD and others


Accurate COD results

Our online COD measurements are ±0.5% 

€ $ £ 

Low Cost COD measurement

No reagent or other consumable costs

10 Sec


A COD measurement every ten seconds


Low Maintenance 

Self cleaning COD probe

Online COD sensor system

Probe System

Photonic Measurements' easy installed UV254 COD system used for optimising your water treatment process. Self–maintained COD measurement with integrated cleaning technology

Online COD Applications


• Food Beverage
• Dairy
• Semiconductor
• Ballast water
• Commercial Aquaculture
• Pharma
• Other Industrial markets


• Distribution system contamination • Reverse Osmosis
• By-product formation
• Detect changes in coagulant demand

Drinking Water

• Source water monitoring 
• Coagulant optimisation
• UV Disinfection

Online COD Benefit


• No consumables
• No ongoing costs
• Long life light source
• Low energy consumption
• No reagent purchase or disposal

Ease of Use

• Measured sample dischargeable to drain
• Communicate results to control room using 420mAmp
• Controls process with two relays for valves and alarms

Trend Data

• Trend Data Measurements every 10 seconds
• Datalogging up to 20 years
• Calibration saved on Probe
• Realtime BOD, COD, TOC & DOC indicative readings in addition to UVA, UVT, IRA, IRT and TSS

Low Maintenance & Install 

• Easy installation and placement
• Automated self cleaning
• Prevents reverse water flow


3 Crescent Business Park
Lisburn, BT28 2GN, GB

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