Process control for monitoring, stabilisation and optimisation
The SEIBOLD Wasser online analyser for Arsenic is used in a landfill leachate Arsenic removal plant. The online measurements are taken at different removal stages to control the whole process.
Our client needed to observe and monitor the Arsenic removal process to improve the process quality and document concentrations at different stages. The unobserved automated online measurements at different process stages, each with it’s own background matrix and signal noise profiles, is a challenging task for an online analyser. SEIBOLD Wasser Arsenic measurements procedure itself, avoiding toxic and dangerous consumables and measurement processes, is unique in this industry. This procedure was developed by SEIBOLD Wasser.
Expectations and purpose of the Multipoint online measurements in Arsenic removal process
- Replacement of the risky laboratory method, measuring Arsenic via transformation to Arsine.
- Increase the data density at all stages from once a week to every 2 hours.
- Process stabilisation and optimisation.
- Automated alarm when exceeding expected concentration at every process step.
- Documentation of outlet concentrations at the end of removal process.
Online measurements at different process stages, each with it’s own background matrix and signal noise profiles
- after biological treatment
- before filter
- outlet removal plant
Results Arsenic removal plant
In the first 6 month after installation there was no unintended and unplanned downtime. The measurement results correlated greatly with laboratory measurement results.
About SEIBOLD Wasser Arsenic measurement procedure
This Arsenic measurement procedure measures Arsenic in water in the range from 1μg-100μ. The measurement itself directly measures Arsenic concentration, without converting Arsenic to Arsine. The procedure and the reagents are researched and developed by SEIBOLD Wasser avoiding the use of any dangerous and toxic ressources. This also decreases the total costs per measurement (TCM(1)) by decreasing the costs for disposal and risc management.
The measurement itself is based on colorimetric complex and uses 2 wavelength for colour change detection. The relevant extinction, used for measurement concentration calculation, is calculated by the speed and intensity of colour change (from green to blue, as seen in the video). This measurement procedures is called “Colorimetric assays”(2).
Recording photometer values while measurement (zero value, adding reagents, wait for complexation and cleaning).
SEIBOLD Wasser online analyser for Arsenic (As)
- Modell: Seibold Composer Wilhelm Kienzl.
- Measurement technology: colorimetric measurement after complex built by reagents.
- Measurement method: colour change intensity and speed for concentration determination.
- Measurement procedure : flow through, closed photometer and stepper motor pumps (one for each liquid, all liquids are pumped).
- Measurement range: 1μg-100μg up to 2500μg via automated dilution As5.
- Fully automated, unobserved measurement of 4 samples at different process stages.
- Measurement interval 120 minutes, controlled by central visualisation.
- Measurement data (concentrations, date/time, photometer values, extinctions, warning, alarm) also collected on SD card.