Improving chemical consumption and process stability through data-driven phosphorus removal at Edar Vic wastewater treatment plant

The Edar Vic wastewater treatment plant (WWTP) is located approximately 60 km north of Barcelona in northeastern Spain and processes both municipal and industrial wastewater. The industrial component accounts for a significant share of the load handled by the plant as it serves a nearby meat processing facility along with other food production sites.

The plant’s treatment process comprises the following steps:

• Primary treatment (without coagulant dosing)
• Biological treatment (without P removal but with nitrogen removal)
• Nitrogen removal
• P removal (chemical precipitation using ferric chloride)
• Anaerobic digestion for biogas production

The plant’s operators, Depuradores d’Osona, are focused on reducing the carbon footprint of their activities, and as such have invested in solar panels to generate renewable power, complementing the power generated from the biogas produced during the anaerobic digestion treatment step.

Building on an existing P control strategy

The Edar Vic plant, a Kemira customer for more than 25 years, already had a strategy in place to control P levels, with an analyzer and a control algorithm developed in-house. The algorithm used P concentration at discharge (after secondary sedimentation) and water flow as input values arguments, adjusting the level of ferric chloride dosing according to phosphorus levels at discharge.

“We have an excellent relationship with the customer, so when they put out a tender request at the end of 2021 it gave us the opportunity to propose different ways to support them,” explains Jordi Ruiz, Advanced Water Treatment Expert at Kemira. “At the time the customer was very satisfied with their own in-house control strategy, but we were confident that our KemConnect P digital service would improve their P control even further, so we included it in our proposal.”

The tender process put a lot of weight on innovative digital solutions, which is an area where Kemira is leading the way in the industry.

KemConnect P is Kemira’s data-driven solution for enhancing phosphorus removal and optimizing chemical consumption in wastewater treatment processes. Once “trained” on site based on testing, Kemira’s algorithm for multiple dosing points enables real-time process optimization, ensuring the right dose of chemicals is administered at the right time and in the right place to maintain compliance at the lowest total cost of ownership.

“The tender process put a lot of weight on innovative digital solutions, which is an area where Kemira is leading the way in the industry,” says Aleix Barrufet, Sales Representative, Kemira. “We have several examples of WWTPs that have reduced chemical consumption and energy costs while improving the stability and effectiveness of their treatment processes. One of the big advantages at Edar Vic was that the plant already had a P analyzer system on site, so we did not need to install our own.”

Practice makes perfect

Following the decision to implement KemConnect P, the next step was to install the necessary hardware and software to gather the data needed and connect the WWTP system to Kemira’s own systems. “We began from July to the end of September by analyzing the system dynamics to build up a picture of the treatment process and how the P control strategy was working with the in-house algorithm,” explains Ruiz. “The data gathered included flow, P values at discharge, and ferric chloride dosing levels. Our experts analyzed the data to see how the plant’s system was responding to the dosing and to help build the parameters for our own algorithm.”

After this initial data gathering and algorithm training period, it was time for KemConnect P to take over the control of ferric chloride dosing, adjusting along the way to optimize the treatment process.

More efficient use of chemistries and improved process stability

Comparing data from the KemConnect P implementation (November 2022 to May 2023) with the same period one year earlier shows coagulant consumption was reduced by nearly 8% on average compared to the previous control strategy. In terms of ferric consumption per kg of P being fed to the WWTP, efficiency improved by over 15%. After the algorithm training period, P levels at discharge lower than 1 mg PO4/L were achieved. Furthermore, optimizing the dosing amount according to the actual situation helped to avoid peaks and troughs in the P values at discharge, meaning a more stable, predictable process.

KemConnect P ensured the plant remained well under the limits set out by the EU Urban Wastewater Treatment Directive while improving the efficiency of the treatment process, resulting in cost savings in terms of chemical consumption.

“KemConnect P ensured the plant remained well under the limits set out by the EU Urban Wastewater Treatment Directive while improving the efficiency of the treatment process, resulting in cost savings in terms of chemical consumption,” Ruiz highlights. “We were achieving 1.15–0.87 mg PO4/l compared to 2.35–0.50 mg PO4/l with the previous strategy. In addition, with KemConnect P the plant’s treatment process can respond quickly to unusual events or process disturbances. This is the big advantage of continuous optimization based on real-time data as opposed to cyclic on-off dosing based on P values at discharge.”

“This case demonstrates that KemConnect P has value for plants that already have some form of monitoring and automation in place,” concludes Ruiz. “There is often room to optimize and do things better even if you’re already actively analyzing and controlling P levels – with the opportunity to realize cost savings, consistent compliance, and increased efficiency.”