MBBR Crodo Italy Fine Bubble Retrievable Aeration

When a soft drink manufacturer in Crodo, Italy needed to reduce organic load on its existing biological treatment, the team implemented a modern MBBR (Moving Bed Biofilm Reactor) solution designed for both treatment performance and long-term operability. Working alongside Depur Padana Acque S.r.l. (DPA) as EPC contractor, SSI Aeration supported a project that combined EEVE700L media, fine bubble diffusers, retention screens, and a retrievable aeration system—a configuration described as the first MBBR installation in Italy pairing these elements together.

The facility required an upgraded head-of-line treatment step to reduce BOD₅ and COD before the existing biological stage, while preparing for increased flows in a planned second step of operation.

Design wastewater flows:

Step 1: 1,214 m³/day

Step 2: 1,700 m³/day

The MBBR upgrade was engineered around a robust aeration and media package designed to maximize oxygen transfer and simplify maintenance.

• Core system components included:
• 396 m³ of SSI EEVE700L media
• Two retention screens
• 800 ECD270-PTFE fine bubble diffusers
• Air supply via blowers in two stages:
• Step 1: 3,400 Nm³/h
• Step 2: 4,000 Nm³/h

Process integration highlights:

• Wastewater pumped into the MBBR using submersible
• pH adjustment to 7.0–7.5 with flow monitoring

This project’s aeration performance was attributed to the decision to use fine bubble diffusers rather than traditional coarse bubble systems—supporting treatment efficiency while reducing air demand.

As documented:

• Fine bubble systems can deliver SOTE ~6.8%, compared with ~2.75% for coarse bubbles
• Smaller bubbles increase total surface area for oxygen transfer, meaning more oxygen with less air
• SSI EEVE700L media is described as engineered to perform optimally with fine bubble diffusers, maximizing compatibility

In the field:

• Minimum air for proper mixing: 7.5 Sm³/m²·h
• Actual (Step 1): ~9.0 Sm³/m²·h

The project notes that alternative solutions may require significantly higher aeration intensity (example given: 15 Sm³/m²·h), which can materially affect lifetime operating cost over a 20–30 year facility service life.

The MBBR upgrade achieved the required effluent quality while giving our customer operational flexibility for the next flow increase. The fine bubble aeration approach reduced the air demand compared with typical coarse bubble designs, and the retrievable aeration system simplifies maintenance without draining the tank.

The installation included a retrievable (removable) aeration system, designed to reduce downtime and simplify interventions.

Documented benefits include:

• Lift-out access without draining the MBBR tank, supporting cleaning/replacement and inspections with minimal downtime
• Faster response to diffuser clogging, mechanical damage, or air distribution imbalance
• Easier future upgrades (e.g., diffuser type changes, aeration density modifications)
• Better long-term energy performance by keeping diffuser condition observable and maintainable

Following reconstruction, the facilities achieved the required effluent quality and maintained process capacity reserve to accommodate increased flow during Step 2, supported by the presence of a DAF unit and post-treatment on a disk filter.

Project Snapshot

• Location: Crodo, Italy (industrial soft drink production)
• EPC contractor: Depur Padana Acque S.r.l.
• First shipment: Mar 10, 2025
• MBBR media: 396 m³ EEVE700L
• Diffusers: 800 ECD270-PTFE fine bubble