
Project's context and challenges
The Stora Enso mill in Ostrołęka is a combined pulp, paper, containerboard and corrugated box mill. The site was operating a high-rate anaerobic reactor that was underperforming, resulting in difficulties in the aerobic treatment stage and leading to extra costs due to the purchase of additional granular sludge. After a successful consultancy by Econvert, the existing high-rate anaerobic reactor was optimized. Shortly thereafter, the first Econvert-IR® reactor was built. Due to its COD removal efficiency and sludge growth, the Econvert-IR® outperformed the original reactor. As a result, Stora Enso decided to retrofit the existing installation with Econvert-IR® internals.
Key figures
30 ton COD/day
Econvert®08024
60 ton COD/day
Econvert-IR®11522
Customer benefits
Operational reliability
High COD removal efficiency
Growth of anaerobic sludge
Small footprint
Able to treat high calcium concentrations in wastewater
Flexibility of Econvert with unique retrofit of existing reactor
Solution
Econvert supplied an Econvert-IR® reactor designed to treat 30 ton COD/d. Once the Econvert-IR® reactor demonstrated superior COD removal efficiency and sludge growth compared to the existing anaerobic reactor, the decision was made to retrofit the original unit with Econvert-IR® internals. After the upgrade, the reactor was able to handle an additional load of 60 ton COD/d.

Scope of supply
- Design and engineering of Econvert-IR®
- Retrofit of existing anaerobic reactor with Econvert-IR® internals
- Supply of all equipment, internals and tanks
- Installation, commissioning & project management
- Start-up and training operators
- Operational support (Services)
Applied solutions
- Econvert-IR®08024
- Econvert-IR®11522
- Biogasbuffer
Other solutions
- Municipal
- Industrial
Anaerobic – Econvert-IR®
- Wastewater
- Industrial water
The Econvert-IR® (Internal Recirculation) is designed to create the ideal process conditions – even under extreme conditions. Thanks to its unique two-stage settling system, (...)
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Anaerobic – Econvert-EGSB®
- Wastewater
Econvert-EGSB® (Expanded Granular Sludge Bed) is the optimal solution after decades of experience, development and optimization. Combining a small footprint with robust internals (...)
- Industrial
Anaerobic – Econvert-UASB®
- Wastewater
- Industrial water
The Econvert-UASB® (Upflow Anaerobic Sludge Blanket) has a proven track record for decades. Its robust and reliable configuration enables the handling of large varieties of wastewater (...)
- Industrial
Anaerobic – Econvert Anaerobic Rental
- Wastewater
- Industrial water
- Resource Recovery
We understand that CAPEX is not always readily available to invest in anaerobic wastewater treatment, or that you may want to avoid long-term financial commitments. At Econvert, (...)
- Industrial
Anaerobic – Econvert-DGF®
- Resource Recovery
- Industrial water
- Wastewater
The Econvert-DGF® (Dissolved Gas Flotation) is an anaerobic solution developed to treat raw wastewater with high concentrations of total suspended solids (TSS) and fats, oils, (...)
- Municipal
- Industrial
Anaerobic – Econvert-Dsulph®
- Resource Recovery
- Industrial water
- Sludge
- Wastewater
Econvert-Dsulph® is a proven, high-efficiency biogas desulfurization solution that combines the chemical absorption of hydrogen sulfide (H2S) in the scrubber with the biological (...)
- Industrial
Anaerobic – Econvert-RTF®
- Wastewater
- Industrial water
The Econvert-RTF® is a regenerative trickling filter which achieves high H₂S removal efficiency, consumes no caustic soda and enables aerobic effluent reuse. The technology (...)
- Industrial
Services: Anaerobic wastewater treatment & biogas
- Wastewater
- Resource Recovery
In the end, it’s not just the equipment that treats your wastewater, it’s the whole process. At Econvert, part of Nijhuis Saur Industries, we offer various anaerobic wastewater (...)