Online analysis system with flow injection analysis for drinking water treatment
Automatic sample water changeover reduces investment costs – Cooperation with the Wasserversorgung Beckum
Water treatment is a demanding process, especially for drinking water as a food product. Quality monitoring is therefore a top priority for public water utility companies. Quite often “manual work” is still needed to this day: Samples are taken on site at the wells or treatment plant filters and then analysed in the laboratory.
Fully automatic monitoring of individual filter modules
Online analysis systems, which automatically determine key parameters, can offer a great deal of potential for optimisation in this field. In close cooperation with the waterworks, Bürkert has developed a solution individually tailored to the drinking water treatment at the Vohren waterworks. The BürkertPlus service division took over installation and start-up and trained the employees on site.
The fully automatic switching block enables the monitoring of individual filter modules with just one measuring unit. This ensures that more detailed information about the water treatment process can be obtained without extensive investment costs.
Preparing yourself for the future: Automated water analysis
The Vohren waterworks belong to Wasserversorgung Beckum GmbH, which employs around 40 people and supplies water to people in an area of over 1,000 square kilometres in the district of Warendorf and parts of the districts of Soest and Gütersloh.
In order to maintain the high-quality standards, also in the future, the waterworks decided to replace the manual and time-consuming sampling process for water treatment monitoring with a more economical and low-maintenance analysis and monitoring concept featuring flat bed aerators and rapid filtration.
“For starters, we compared decentralised and centralised solutions, meaning that we weighed up whether it made more sense to use analysis systems directly at the total of six measuring points in the factory, or whether a central analysis station for all filters would be more practical for us”, said waterworks supervisor Matthias Schürhörster.
It was also important to consider both the technical and financial aspects. On the one hand, automatic monitoring of the measuring points had to be implemented to relieve the burden on the workers and to guarantee high quality, also in the future. On the other hand, it was also necessary to minimise the installation and maintenance effort.
Central analysis of the water parameters
Ultimately, the decision was taken in favour of a central water analysis solution. The backbone is the Type 8905 online analysis system from Bürkert which combines microfluidic system modules for the continuous analysis of the most important water treatment parameters in just one compact device. It automatically determines the pH value, turbidity and the oxygen and iron content in the outlet of the rapid filters.
The modular water analysis system works with innovative MEMS technology (micro-electro-mechanical systems) and enabled replacement and expansion of the existing measuring points, thereby making measurements practical and future-proof. Unlike the glass probes widely used previously, the microchips do not require constant replacement.
Flow injection analysis to determine the iron content
“Even the iron content is now determined fully automatically through modern flow injection analysis (FIA)”, says a delighted Schürhörster. The FIA module for the analysis of the iron content now combines all the necessary components, including the controller, in the smallest of spaces.
What was previously only possible in the laboratory is now done by a small, compact sensor cube of the online analysis system. The special feature is a comprehensive miniaturisation using microfluidic components: When using flow injection analysis, the reagent is added to the sample water via a pump. The microfluidic mixing section following the injection provides for even and complete mixing. The homogenous measured liquid then passes through a flow photometer that measures the absorption over time. The iron content can be determined photometrically from the detected peak-shaped signal and is then available for controlling, monitoring and documenting the water treatment process.
Microfluidics determine the iron content: Miniaturised FIA module for the online analysis system
Device integration via EDIP
Communication takes place via the device platform EDIP (Efficient Device Integration Platform), which enables intelligent networking of all electronic Bürkert devices. Thanks to the digital measuring concept, all the measuring parameters, switching intervals and settings – e.g. for self-diagnosis – can be displayed on a 7-inch touch display, adjusted and transmitted to the control system of the waterworks via a bus interface. As a result, all the analysis data is available at a central location. Filter contamination can thus be detected and removed in good time before the treatment process is disrupted.
Sample water changeover and automatic sensor cleaning
To ensure each rapid filter can be checked separately, valve switching was implemented for the individual sample waters. Water is thus led from each filter to the analysis system and then switched between the individual lines by a solenoid valve.
Automatic switching could be implemented via the device’s internal visual programming software; thus no additional programming was required at the PLC. To minimise the level of maintenance, an additional cleaning unit was installed, meaning the analysis unit can now be cleaned in a time-controlled and fully automatic manner. Depending on the water quality, the sensors need to be cleaned at regular intervals in order to remove limescale, iron or organic deposits and, if necessary, recalibrated. The automatic cleaning system MZ20 carries out automatically all the tasks which once had to be done by hand.
The cleaning system cleans the measuring cells independently and fully automatically at routine intervals.
Online Analysis System
- For analysis applications for drinking water and fresh water in industrial processes
- Modular sensor and electronic system: - up to 6 measurements in one housing - up to 30 analysis sensor cubes in one Bürkert system bus (büS)
- Prepared for fielbus connectivity and remote access
- MEMS technologies allows minimal footprint and minimum sample water demand
- Automatic cleaning for type MSxx sensor cubes
- Protection against clogging in the system and inside the sensor cubes for long time accurate measurements
- Different cleaning solutions for organic and inorganic contamination
- Application specific programmable cleaning cycle