Stable pH measurement for reliable water treatment at BASF

pH measurements in polymer-containing process flows are challenging, especially when it comes to wastewater. At BASF Heerenveen, pH fluctuations caused disruptions in the ultrafiltration installation. In this case study, you can read how an automatic cleaning solution delivers stable pH measurements, reduced maintenance and reliable operation of the water treatment process.

BASF Heerenveen, specialist in water-based polymers for inks and coatings

BASF in Heerenveen develops and produces water-based binders for the printing ink and coating industry. A large part of these polymers is used in sustainable inks for food packaging. These additives contribute to the optimal colour and gloss quality of paints and coatings.

The automatic cleaning of the pH sensor ensures reliable measurement without any extra effort on the part of our employees.

Mark Lazonder, Asset Manager BASF Netherlands

Stable pH measurement in a polluting water flow

pH measurement in water treatment

Well-controlled water treatment plays an important role in this production environment. In Heerenveen, the polymer-containing process flow is first treated by ultrafiltration (UF) before the permeate water enters the internal water treatment system.

The UF installation is used to thicken polymers from the influent. The water passes through the membranes, while the thickened polymer fraction is collected and reused. The efficiency of this thickening process is highly dependent on the pH value of the process flow, however.

In practice, pH fluctuations were found to have a negative impact on the thickening factor of the UF installation. If the pH was too low or unstable, insufficient polymer was collected. This not only impacted the efficiency of the process, but also the operational reliability of the water treatment.

Initially, there was little control due to a lack of continuous measurement. Manual measurements showed that the pH was often outside the optimal range, which was not noticed in time.

An additional challenge is the film-forming behaviour of the polymers present, which easily adhere to surfaces, including pH sensors, causing contamination and compromising reliability.

Measurement objective: insight and control

BASF wanted to continuously monitor the pH value upstream of the ultrafiltration installation. Accurate measurement of this value allows the pH to be adjusted in good time by means of dosing, before the process flow reaches the UF installation.

Stable and continuous pH measurement allows for:

optimisation of the thickening factor of the UF installation
thickening of polymers

This is why low-maintenance and reliable pH measurement was necessary, even in this complex and polluting process flow.

The pH measurement remains stable: re-calibration was not necessary even after six months.

Mark Lazonder, Asset Manager BASF Netherlands

Automatic cleaning for reliable pH measurements

To ensure reliable pH measurements, BASF opted for an inline pH solution with automatic cleaning. The installation consists of:

a Knick Stratos Multi transmitter
a Knick Uniclean 720 for automatic sensor cleaning
a pneumatically controlled retractable fixture

This setup automatically retracts the pH sensor from the process pipe and cleans it with water. The Uniclean 720 controls both the cleaning and retraction of the sensor, fully integrated into the process.

This approach greatly reduces sensor contamination and ensures long-term reliable pH measurement without interrupting the process.

Stable measurement without extra effort

Automatic cleaning guarantees stable and reproducible pH measurement, even in a flow containing polymers. Sensor maintenance has been significantly reduced and manual intervention by the maintenance team is now hardly ever necessary.

This contributes to:

better controlled operation of the ultrafiltration unit
more stable water treatment process
less work pressure for employees

Collaboration with ELSCOLAB

BASF was able to count on ELSCOLAB's technical support for this atypical pH application. Through joint deliberation about the application and the correct configuration, a solution was developed that meets the specific process requirements.

BASF experienced the collaboration as pleasant, open and transparent, with clear technical support throughout the process.

Are you also looking for reliable pH measurement in a complex process flow?

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