I need to collect information about a wastewater treatment plant based on MBBR but without addition of any chemical in the treatment line. Do you know if such a plant exists?
Yes but not as shown in your picture (2 aerated sections).
For biological phosphorus removal, a full anaerobic (no dissolved oxygen, no nitrate, no sulfate, ...) stage would needed with upstream selector and full modulating process controls (ORP, DO).
If interested, I would be happy to provide more details via email.