Wastewater analysis: Precise solutions for clean water and legal certainty

Photometric determination of constituents is the undisputed standard in municipal and industrial wastewater monitoring. Whether you need to determine classic sum parameters such as COD (chemical oxygen demand) and BOD (biological oxygen demand) or monitor nutrients such as ammonium, nitrate, nitrite, and phosphate, we have the right equipment for precise results.

• Spectrophotometers & Photometers: Our range extends from robust, mobile handheld devices for quick checks at the poolside to high-end spectrophotometers for certified laboratories. Modern devices from Köhler feature intuitive touch operation, guided menus, and automatic recognition of cuvette tests via barcodes. This drastically minimizes user errors.
• Round cuvette tests & reagents: We offer a wide range of ready-made test kits for almost all relevant parameters. These ready-to-use solutions minimize contact with hazardous chemicals and guarantee maximum repeatability and batch consistency thanks to standardized industrial manufacturing.
• Thermal blocks & digestion: Reliable thermal reactors are essential for the chemical digestion of samples (e.g., for COD or total phosphate determination). Our devices guarantee precise temperature control and safety in continuous operation, including automatic shutdown and overheating protection.

Our expert tip: Ask us about customized call-off orders for your annual cuvette test requirements. We can help you optimize storage costs, keep track of expiration dates, and avoid delivery bottlenecks.

Manual sampling is important, but often only provides a snapshot. It is frequently insufficient for truly understanding the dynamics of wastewater flows, especially in the case of intermittent loads or heavy rainfall events. Continuous online measurements and representative composite samples are the key to a deep understanding of the process and seamless monitoring.

• Automatic sampling devices (samplers): We offer stationary and portable samplers that work exactly according to your specifications – whether time-proportional, quantity-proportional, or event-proportional. This ensures that your analysis is based on a representative database that is 100% compliant with water law requirements. Our devices feature active cooling to keep the sample stable until analysis.
• Online sensors: Monitor critical parameters such as pH value, conductivity, turbidity, redox potential, or dissolved oxygen in real time directly in the process. Our partners offer robust, low-maintenance probes (e.g., optical oxygen probes) that work reliably even in harsh, contaminated environments and have a long service life thanks to cleaning functions.
• Container stations & measuring houses: For larger plants or remote discharge points, we work with our partners to design complete, walk-in measuring stations. These protect your valuable technology from weather, frost, and vandalism, while also providing a safe workplace for maintenance work.

An analytical measurement is only as good as the preparation of the sample. Suspended solids, particles, or emulsions can interfere with sensitive measuring instruments, clog capillaries, or distort results due to scattered light. Clean filtration is therefore often the first step toward obtaining the correct result.

• Premium filter papers & membranes: Whether for the gravimetric determination of filterable substances, for preparation for HPLC, or for clarifying samples prior to photometry—we carry filters in all pore sizes and materials (glass fiber, cellulose, syringe filters, membrane filters).
• Extraction sleeves: For the analysis of organic pollutants, we offer high-quality sleeves made of cellulose or glass fiber, which ensure consistent extraction conditions in Soxhlet apparatus.

In our online shop, you can quickly and easily find the right consumables to keep your laboratory routine running smoothly.

Handling wastewater and chemical reagents involves specific risks. Biological agents (bacteria, viruses), splashing water, and aggressive chemicals (strong acids for digestion) require consistent and uncompromising occupational safety measures. As a responsible laboratory equipment supplier, we care about your health and that of your employees.

Our PPE range at Köhler includes:

• Chemical protective gloves: Tested and certified for handling acids, alkalis, and organic solvents commonly used in laboratories. We pay attention to fit and tactile sensitivity so that precise work is not restricted.
• Respiratory protection: From simple FFP3 masks for dust to full-face masks with gas filters for working in confined spaces or where aerosols are present.
• Eye protection & body showers: Essential basics for every laboratory workplace, including eye wash bottles for quick first aid use.
• Disposable clothing: Coveralls and gowns to protect personal clothing from contamination.

Here we answer some of the most common questions our customers ask the Köhler team.

Which parameters must I measure in wastewater?
This depends largely on your specific water law permit (discharge permit for indirect or direct dischargers) and your industry. The classic parameters are almost always COD, pH value, temperature, conductivity, ammonium, nitrate, phosphate, and filterable substances. We are happy to help you put together the right equipment for your individual monitoring plan.

What exactly is the difference between COD and BOD?
COD (chemical oxygen demand) indicates how much oxygen is required for the purely chemical oxidation of all organic substances in water – essentially the "total pollution." The BOD (Biochemical Oxygen Demand, usually BOD5), on the other hand, only measures the oxygen that microorganisms need to break down organic substances within 5 days. The ratio of both values (COD/BOD) provides important information about the biodegradability of the wastewater.

How often do automatic sampling devices need to be serviced?
To ensure representative samples and avoid cross-contamination ("memory effects"), the suction hoses and dosing systems should be regularly rinsed, cleaned, and checked for cracks. We recommend thorough technical maintenance by qualified personnel at least once a year, or more often in the case of heavily contaminated wastewater.

Does Köhler Labor also offer reagents for devices from other manufacturers?
Yes, absolutely. We are not tied to any single manufacturer. In many cases, we can procure compatible reagents or original accessories from various well-known brands. Simply contact us with your device type and we will find a solution.