What is BOD measurement?

BOD measurement is an important part of water and wastewater analysis. BOD stands for Biochemical Oxygen Demand. The value shows how much oxygen microorganisms need to break down organic substances in a water sample.

The BOD value is a key parameter, particularly at wastewater treatment plants, environmental labs, industrial facilities, and research institutions. It helps assess the organic load of water samples more accurately and reliably monitor wastewater treatment processes.

OxiTop® by WTW – proven for BOD determination

With the OxiTop® measuring system from WTW, biochemical oxygen demand can be determined simply, safely, and conveniently. The system works on the respirometric measurement principle. Oxygen consumption in a sealed sample bottle is detected via a change in pressure.

The advantage: measurement happens directly within the system, without laborious manual calculations. Depending on the version, readings are displayed clearly, documented, and evaluated. This makes OxiTop® especially well suited for labs that regularly determine BOD values and place value on simple operation, reproducible results, and efficient workflows.

Why choose OxiTop® for BOD measurement?

Daily lab work demands reliable technology, clear workflows, and dependable results. This is exactly where OxiTop® offers clear advantages.

Key benefits at a glance:

• Simple BOD measurement in water and wastewater samples
• Respirometric measurement principle via pressure change
• Direct display of BOD values, depending on the system version
• Suitable for self-monitoring, laboratory analysis, and environmental monitoring
• Convenient handling thanks to well-designed WTW system technology
• Ideal for treatment plants, in-house labs, industry, and research
• Various system configurations for different sample numbers and requirements

Typical application areas for OxiTop®

OxiTop® is used wherever the oxygen consumption of biological degradation processes needs to be reliably determined. The system is especially common in the following areas:

Wastewater treatment plants and municipal wastewater technology In municipal wastewater analysis, regular monitoring of the BOD value is an important part of process control. OxiTop® helps labs measure samples efficiently and reliably document trends over time.

Industrial and in-house labs Industrial wastewater must also be tested regularly. Especially in sectors such as food production, chemicals, pharmaceuticals, biotechnology, or surface treatment, BOD measurement can provide important insight into organic load.

Environmental analysis and research In environmental labs, universities, and research institutions, OxiTop® is used for water samples, degradation studies, and respirometric tests. This makes the system suitable not only for routine analysis but also for more advanced investigations.

How does OxiTop® BOD measurement work?

For BOD measurement with OxiTop®, the sample is placed in a special measuring bottle. Microorganisms break down the organic constituents and consume oxygen in the process. The carbon dioxide produced is absorbed within the system. Oxygen consumption creates a pressure change, which is detected by the OxiTop® measuring head.

The BOD value is calculated and displayed based on this pressure change. This makes the method especially user-friendly, since many steps are simplified and readings can be tracked conveniently.

OxiTop®-i and OxiTop®-IDS – modern solutions for BOD analysis

WTW offers various OxiTop® variants for different requirements. The OxiTop®-i system is especially well suited for classic BOD self-monitoring and offers simple operation directly at the measuring head.

The OxiTop®-IDS system is the modern solution for labs that also place value on digital data transfer, documentation, and flexible evaluation. Thanks to digital system integration, measurement data can be conveniently processed further.

Which variant is the right fit depends, among other things, on the number of samples, the desired documentation, the lab's workflow, and the requirements for evaluation.

Who benefits from an OxiTop® system?

An OxiTop® BOD measurement system is especially worthwhile for labs that regularly determine BOD values and want to save time, reduce sources of error, and standardize their workflows.

OxiTop® is suitable for, among others:

• Wastewater treatment plants
• Environmental labs
• Industrial labs
• Research institutions
• Colleges and universities
• Quality control in production and process monitoring
• Labs for water and wastewater analysis

Conclusion: OxiTop® makes BOD measurement easier

BOD determination is an important parameter in water analysis. With OxiTop® from WTW, labs get a proven, user-friendly, and reliable system for respirometric BOD measurement.

Whether at a treatment plant, environmental lab, or industrial facility: OxiTop® helps determine BOD values efficiently, simplify measurement workflows, and evaluate results reliably.

Buy OxiTop® BOD measurement systems and accessories

Looking for the right WTW OxiTop® system for BOD measurement, or need accessories for your existing BOD analysis setup?

häberle LABORTECHNIK helps you select the right OxiTop® systems, measuring heads, stirring platforms, sample bottles, and accessories for your application in water and wastewater analysis.

OxiTop® by WTW – measuring BOD simply and reliably.

Potential sources of error with the BOD measurement system

Even with a reliable BOD measurement system like OxiTop®, results can be affected by certain application errors or sample conditions. Clean working practices, correct sample preparation, and adherence to the specified measurement conditions are therefore essential for reproducible BOD values.

1. Incorrect sample volume The sample volume must match the expected BOD measuring range. If the wrong volume is used, the measuring range may be exceeded, or the sensitivity of the measurement may be compromised. Before measuring, you should check which BOD range is expected and which sample volume is appropriate for it.

2. Leaking measuring bottles or measuring heads Since OxiTop® BOD measurement is based on a pressure change in a closed system, leaks can distort the result. Measuring bottles, seals, and measuring heads should therefore be clean, intact, and properly sealed before use.

3. Unsuitable or inadequately prepared sample Heavily loaded, toxic, or particle-rich samples can affect microorganism activity. Insufficient homogenization of the sample can also lead to deviating results. Before measurement, the sample should be well prepared and treated according to the intended method.

4. Missing or incorrect inhibition of nitrification In certain wastewater samples, nitrification can additionally increase oxygen consumption. This can result in a higher measured BOD value. Depending on the purpose of the analysis, the use of a nitrification inhibitor may be necessary to determine carbonaceous BOD specifically.

5. Incorrect storage temperature or temperature fluctuations BOD measurement is temperature-dependent. If samples are not incubated at the intended temperature, or if strong temperature fluctuations occur during the measurement period, this can affect biological activity and therefore the result.

6. Insufficient oxygen supply at the start of measurement Sufficient oxygen must be present in the system at the start for a correct BOD determination. If the sample load is too high or not properly diluted, oxygen consumption can exceed the measuring range. In such cases, sample dilution is required.

7. Contaminated vessels or residue from cleaning agents Residue in measuring bottles, seals, or stir bars can inhibit biological activity or cause additional oxygen consumption. All components should therefore be thoroughly cleaned and free of interfering residues.

8. Incorrect calibration, operation, or documentation Operating errors can also lead to deviating BOD values. These include incorrectly selected measuring ranges, measurements not started correctly, mixed-up samples, or incomplete documentation. A clear lab routine and trained personnel help avoid these sources of error.

Practical tip for reliable BOD results

For reliable results with OxiTop®, sample volume, temperature, measuring range, incubation time, and sample preparation should be carefully coordinated with one another. It's also recommended to regularly perform control measurements and check accessories such as seals, measuring bottles, and stirring systems for proper condition.

This helps reduce typical sources of error in BOD measurement, keeping results traceable, comparable, and reproducible.