WUPPERTAL MUNICIPAL UTILITIES
Case Study: Reactivation Using Sustainable Coconut-Shell-Based Make-Up Carbon
WSW Energie & Wasser AG (WSW) is part of Wuppertaler Stadtwerke GmbH, located in the German federal state of North Rhine–Westphalia. WSW operates three water treatment plants with a total of 24 granular activated carbon (GAC) filters: Dabringhausen (12 filters, approx. 45m³ each), Herbringhausen (7 filters, approx. 75m³ each), and Benrath (5 filters, approx. 65m³ each).
While the Dabringhausen (Große Dhünn Reservoir) and Herbringhausen (Herbringhausen and Kerspe Reservoirs) plants treat reservoir water, the raw water for the Benrath plant comes from the bank-filtered water from the Rhine River.
WSW supplies drinking water to 358,876 people in Wuppertal via a distribution network spanning 1,114km. With 40 separate pressure zones, numerous pumping stations and pressure boosting systems, as well as redundant supply loops, the network ensures a reliable water supply for the population.
Wuppertaler Stadtwerke GmbH is committed to innovative and sustainable solutions with the goal of becoming climate neutral. By 2030, the company aims to reduce its CO₂ emissions by 80% compared to the 1990 baseline year.
The Challenge
Until 2019, re-agglomerated, coal-based activated carbon was used in all three water treatment plants. Jacobi used AquaSorb™ 6300 as make-up carbon in regular reactivation projects.
Due to the characteristics of the raw water being treated, particular attention had to be paid to the potential leaching of heavy metals from the coal-based activated carbon, requiring specialised analytical methods. Despite these measures, WSW repeatedly experienced leaching of aluminium (and/or other metals) when recommissioning their GAC filters after reactivation. As a result, extensive flushing was required before the filters could be returned to service and reconnected to the drinking water network.
In cooperation with the DVGW Technology Centre for Water (TZW – Technologiezentrum Wasser), WSW investigated the performance of a potential alternative to coal-based activated carbon: a suitable activated carbon made from coconut shells.
The Solution
In 2019, WSW and Jacobi agreed to use coconut-shell-based make-up carbon in a pilot filter during the next scheduled reactivation at the Dabringhausen water treatment plant.
Performance was closely monitored and, from 2020 onwards, the coconut-shell-based activated carbon AquaSorb™J200 was adopted as the standard make-up carbon for regular reactivations at the Dabringhausen and Herbringhausen plants.
The Result
By switching to coconut-based activated carbon, we were not only able to resolve the key issue of heavy metal leaching in reservoir water treatment but also achieved a positive impact on overall make-up carbon demand. This is because coconut-shell-based activated carbon is typically more highly activated and can be reactivated with a higher iodine number. In addition, coconut-shell-based carbon has greater mechanical hardness, resulting in lower carbon loss during reactivation.
In 2022, all filters at the Dabringhausen and Herbringhausen water treatment plants were converted to AquaSorb™ CX, also a coconut-shell-based activated carbon.
The monitoring results and subsequent analyses were jointly published by TZW and WSW in the article “Activated Carbon in Water Treatment Plants: How Coconut Shells Can Replace Bituminous Coal” (DVGW energie | wasser praxis, 10/2023).
The full article is available here
In 2024, the third and final WSW water treatment plant in Benrath was also converted from coal-based activated carbon to sustainable coconut-shell-based activated carbon, enabling the future use of AquaSorb™ CX as make-up carbon there as well. The complete transition to coconut-based, resource-efficient activated carbon across all three water treatment plants has delivered the desired solution and has significantly improved the carbon footprint of Wuppertaler Stadtwerke.
We are pleased that our team of experts has been able to provide Wuppertaler Stadtwerke with an optimal solution that also supports their long-term sustainability goals,namely, reducing their CO₂ footprint by 80% by 2030.
“What convinced us most was the quality and ease of handling — along with the time and cost savings. Since coconut-based activated carbon poses virtually no risk of heavy metal leaching, the additional costly analyses and increased flushing requirements are no longer necessary. This allows us to return the filters to operation more quickly after reactivation.”
Markus Klemann, Head of Water Treatment at WSW