Municipal wastewater treatment plants are facing two converging pressures: rising sludge disposal costs and stricter requirements for removing trace organic contaminants. A recent ozone system upgrade at the Bottrop wastewater treatment plant in Germany demonstrates how utilities can address both challenges with a single, well-integrated solution.
Bottrop’s Dual-Focus Upgrade
The Bottrop plant serves approximately 1.34 million population equivalents and has a maximum design flow of 8.5 m3/s. Its upgrade project has two goals. The first is sludge reduction. The second is micropollutant removal, which is also being studied as part of the project.
Sludge Reduction: Cutting Costs at the Source
Sludge disposal is a major operating expense for many wastewater plants. Transport, energy, and final disposal costs have all risen sharply in recent years. Reducing the volume of biological solids produced is therefore a direct way to improve a plant’s financial performance. In Bottrop, the target is a 30–50% reduction in sludge production.
The approach relies on ozone oxidation. Ozone attacks bacterial cell walls and complex organic structures, breaking them down into smaller, more biodegradable compounds. This weaker, partially oxidized material is then more easily degraded in the biological treatment train, so less residual sludge remains for disposal.
This method also brings additional operational benefits. Plant operators can expect better sludge settling, improved dewatering performance, and fewer problems with sludge bulking. Chemical use for conditioning may decline, and overall running costs can drop. These advantages make ozone a practical option not just for large facilities but also for midsize plants looking for operational efficiency.
Micropollutant Removal: A Growing Requirement
Pharmaceutical residues, hormones, and ingredients from personal care products are increasingly detected in water bodies. These compounds are present in very low concentrations, but their molecular structures are complex enough to resist conventional biological treatment. Advanced oxidation, especially ozone, can break down many of these substances effectively.
At Bottrop, a portion of the ozone output will be used in a separate test basin to evaluate the oxidation of pharmaceuticals and personal care ingredients. This research will provide practical data on removal efficiency and help guide future full-scale applications.
EU Regulation Raises the Bar
The revised EU Urban Wastewater Treatment Directive (EU 2024/3019), published in 2024, sets new expectations for micropollutant control. For relevant trace substances, treatment plants will generally need to achieve an 80% removal rate. That target is difficult to meet with biological treatment alone. As a result, many European utilities are now assessing ozone as a tertiary treatment step. The Bottrop project is one of the first large-scale implementations under this new regulatory momentum.
Evotide: One Platform, Two Functions
The selected system is Wedeco’s new-generation Evotide ozone equipment, supplied by Xylem. This order marks the first commercial project for Evotide since its global launch. The system has a total capacity of 20 kg O3/h at 10 wt%. Of this, 16 kg O3/h is reserved for sludge oxidation, while up to 4 kg O3/h is available for micropollutant removal.
Containerized Design Eases Retrofit
For existing plants, equipment performance is only part of the decision. Installation complexity can cause extended shutdowns and higher project costs. The Evotide system is containerized, with the ozone generator, electrical controls, and auxiliary components integrated onto one platform. Factory assembly and testing reduce the need for on-site labor and shorten commissioning. This modular design also lowers integration risk, accelerates project delivery, and reduces interference with normal plant operations.
Energy Efficiency with Effizon evo 3G
Evotide uses Wedeco’s latest Effizon evo 3G electrode technology. This allows stable ozone output across a wide operating range. Compared with earlier technology, it can reduce energy consumption by up to 15%, improve production stability, and lower maintenance needs. Fewer unplanned outages is another important advantage for municipal facilities that must run continuously. Over the lifecycle of a treatment plant, these improvements have a direct impact on total cost of ownership.
Filtration’s Role in Protecting Ozone Systems
Ozone systems are efficient, but they perform best when upstream solids are well controlled. Suspended particles can create additional ozone demand, foul diffusers or contactors, and complicate downstream polishing steps. For plants planning ozone upgrades, pre-filtration should be part of the engineering review.
Spuretek Filtration Co., Ltd. supplies a range of depth and surface filtration products for water treatment applications. High-flow pleated filters such as the SHF series can handle large flow rates with low pressure drop, making them suitable as pre-filtration ahead of ozone contactors. SMB melt-blown cartridges offer cost-effective depth filtration for general suspended solids removal. For applications where bag filtration is preferred, SFB filter bags provide a simple and scalable solution. In cases with aggressive chemicals or high temperatures, SSSP stainless steel pleated filters can be an appropriate alternative.
Selecting the right filtration geometry, pore size, and filter medium requires site-specific analysis. Spuretek’s team can help operators and engineering firms determine the best way to protect ozone equipment and maintain downstream water quality.
Looking Ahead
The Bottrop project shows how a single ozone system can serve both sludge reduction and micropollutant removal. It also highlights broader trends: regulations are tightening, energy costs are under scrutiny, and retrofit-friendly equipment is gaining preference. Utilities that act now can position themselves for future compliance while improving operational efficiency.
For more information about filtration solutions for ozone and other advanced water treatment processes, contact Spuretek Filtration Co., Ltd. at https://www.spuretek.com.
Source: H2O-China — https://www.h2o-china.com/news/364574.html
Based on reporting by H2O-China. Original analysis and product perspective by Spuretek Filtration Co., Ltd.. Read the source.