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Solenis Recognizes Repsol Industrial Complex in Cartagena as Winner of a 2023 Sustainability Award

February 29, 2024


Solenis is pleased to award Repsol Industrial Complex in Cartagena with a 2023 Sustainability Award.

WILMINGTON, Del. (USA) – Solenis LLC, a leading global producer of specialty chemicals, is proud to announce that Repsol, a global multi-energy company, is among the winners of a 2023 Solenis Sustainability Award in recognition of an innovative project to reduce energy use and increase water reuse at its industrial complex’s wastewater treatment plants in Cartagena, Spain.

Repsol is being recognized for process improvements to the plant’s dissolved air flotation (DAF) system. These improvements increased the facility’s efficiency and reduced sludge production, allowing the plant to use 20% less energy or 113,880 fewer kW hours per year. The changes also allowed the plant to increase its water reuse.

The Cartagena plant was experiencing challenges in its wastewater treatment processes, particularly in the DAF system, which clarifies wastewater by removing suspended solids, oils, greases, biochemical oxygen demand (BOD), chemical oxygen demand (COD), and metals. The system encountered performance and corrosion issues, along with difficulties controlling the pH in the biological reactor.

Recognizing the need for a comprehensive solution, Repsol partnered with Solenis, a trusted partner and solutions provider. Solenis conducted on-site visits, thorough analysis, and preliminary studies to understand the unique requirements of Repsol’s plant. Solenis experts designed a customized action plan to address the challenges.

The key recommendation was to replace ferric chloride with Chargepac™ 312 in the DAF system, with a swap ratio of 12:1. The impact was transformative — sludge production decreased by 8,000 metric tons per year. This contributed to reduced transportation costs of about $86,000 per year and a reduced carbon footprint. 

Furthermore, the change resulted in a better balance between COD, nitrogen, and phosphorus in the biological reactor. The solids in the biological reactors were reduced by more than 50%, maintaining the efficiency in reducing COD. With the more efficient system, the plant used about 20% less energy, equivalent to 113,880 fewer kW hours annually. This enhanced environmental performance and allowed Repsol to operate within effluent parameters with a higher contingency buffer, ensuring compliance with environmental regulations.

The project yielded impressive environmental benefits, including a reduction of 82 metric tons of CO2 per year.

Repsol is honored to receive this sustainability award, which acknowledges the company’s commitment to environmental stewardship and collaborative efforts with partners like Solenis. As the director of the Repsol industrial complex in Cartagena, Antonio Mestre said, “We are thrilled with the remarkable improvements achieved through our collaboration with Solenis. The expertise and dedication demonstrated by their team have not only addressed our operational challenges but exceeded our expectations. The transition to Chargepac™ 312 in the DAF system was seamless, and the results speak for themselves — significant cost savings, reduced energy consumption, and enhanced environmental performance. Working with Solenis was not only effective but also remarkably smooth, showcasing their commitment to understanding our unique needs. It’s a testament to the power of collaboration and innovation in driving positive change."

Solenis established the Sustainability Awards in 2020 to recognize projects that deliver reduced water use, reduced energy consumption, decreased greenhouse gas emissions, optimized raw material utilization or reduced waste. Read more about the awards and winning projects on

<div class="line">&nbsp;</div> <h2>About Solenis</h2> <p>Solenis is a leading global producer of specialty chemicals focused on delivering sustainable solutions for water-intensive industries, including consumer, industrial, institutional, food and beverage, and pool and spa water markets. Owned by Platinum Equity, the company&rsquo;s product portfolio includes a broad array of water treatment chemistries, process aids, functional additives, and cleaners and disinfectants, as well as state-of-the-art monitoring and control systems. These technologies are used by customers to improve operational efficiencies, enhance product quality, protect plant assets, minimize environmental impact, and create cleaner and safer environments. Headquartered in Wilmington, Delaware, the company has 69 manufacturing facilities strategically located around the globe and employs a team of over 16,100 professionals in 130 countries across six continents. Solenis is a 2023 US Best Managed Company, recognized three years in a row.</p> <p>For additional information about Solenis, please visit <a href="/en/"></a> or follow us on social media.</p>
<h2>About Repsol</h2> <p>Repsol is one of the top companies in the oil and gas industry and is present across the entire value chain: exploration and production, transformation, development, and marketing of energy that is efficient, sustainable, and competitive for millions of people. With over 80 years of experience, Repsol has been present in the entire oil and gas value chain in a sustainable and competitive way.</p>


Europe, Middle East and Africa

Gillian (Gill) Davies

Senior Manager, Corporate Communications, Eurasia