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PUREFLOW BIO / ENGINEERING FIELD GUIDE

Moving Bed Biofilters (MBBR)Design and Operation

Moving bed biofilters (MBBR): how they work, fill level, aeration, sizing, placement, start-up and problems such as floating media, high nitrite and falling pH.

Explore the process ↗Open the workbench
10 MIN GUIDEUPDATED NOVEMBER 2026
Reference illustration for Moving Bed Biofilters (MBBR): Design and OperationEQUIPMENT REFERENCE
Equipment reference illustration. Confirm the supplied model configuration and installation arrangement from its approved documentation.
01Understand the mechanismInspect the relevant process stages.
02Review the operating dutyKeep assumptions and measured values visible.
03Prepare the next decisionUse the guide, tools and project checks.
INTERACTIVE PROCESS ATLAS

See the mechanism.
Understand the duty.

Select a route or a stage to inspect the process. The cutaway explains the equipment and water environment; it is a teaching illustration, not a project drawing.

Swipe horizontally to inspect the equipment. Stage buttons below also centre the selected component.
Aerated biological treatment and samplingPUREFLOW / INTERACTIVE PROCESS ATLASCONCEPT LAYOUT · NOT TO SCALETAN-NpH°CPRE-SCREENED SUPPLYBIOFILM ON MOVING CARRIERSMEASURE THE PROCESSAIR DISTRIBUTIONNH₄⁺ → NO₂⁻ → NO₃⁻Motion explains the process; it is not a measured flow rate or biological time model.
Pre-screened water reaches the biological stage and continues through the retained-media outlet.
Selected process stage

Feed the reactor

Define peak feed and the nitrogen load.

How it works

Pre-screened water enters the biological stage. Effective upstream solids removal helps protect the reactor.

What to establish
  • Define peak feed and the nitrogen load.
  • Check oxygen, pH, alkalinity and temperature.
  • Use supported media performance and the specified fill arrangement.

Continue this guide ↗

Motion explains direction and mechanism; it does not represent measured performance. Geometry, stage order, pipe routes and equipment configuration are conceptual. Use the approved project design, operating instructions and verified model data.

Key takeaways

  • Air is the engine: it moves the media and supplies oxygen.
  • Use the media fill share specified for the reactor and carrier; confirm that the media can circulate as intended.
  • Pre-filter solids so the media stays clean.
  • Mature the filter for several weeks before loading it.
Reference illustration for Moving Bed Biofilters (MBBR): Design and Operation
Equipment reference visual; not evidence of a completed installation.
THE SHORT ANSWER

From ammonia to nitrate in four steps

  1. Pre-filtered water flows inSolids already removed.
  2. Air keeps everything movingAeration grid.
  3. Bacteria do the workBiofilm on carriers.
  4. Fresh water flows outRetained by a screen.
Moving Bed Biofilters - Pureflow Bio
Reference visual. Equipment configuration and project details must be confirmed separately.
Moving Bed Biofilters - Pureflow Bio
Reference visual. Equipment configuration and project details must be confirmed separately.
BIOFILTERS

How full should it be?

Use the fill share specified for the reactor and carrier. Check circulation, aeration and retention at the intended operating load.

PLANNING WORKBENCH

Work with your own numbers.

Use the tools below to explore the relevant arithmetic. Enter measured values or declared assumptions. An estimate does not establish equipment capacity, biological performance or a safe operating limit.

Biofilter media planning scenario

Relate a defined nitrogen load to an explicitly supplied media conversion rate and fill share.

Assumptions and limits

Use a conversion rate verified for the media, water chemistry, oxygen, temperature and load. Example numbers are arithmetic inputs, not approved biological capacities or fill recommendations.

—TAN-N load · g/day
—Media volume · m³
—Nominal reactor volume · m³
Enter your values, or load the labelled arithmetic example. No design values are pre-filled.
FormulaMedia m³ = feed × TAN-N yield ÷ conversion rate. Reactor m³ = media m³ ÷ fill fraction.
Convert units before you calculate
Choose units and enter a value.

Planning arithmetic · inputs remain visible for review · example values are not operating recommendations

BIOFILTERS

Air is the engine

Set airflow so all media moves gently, without violent tumbling. It also supplies oxygen and strips CO2 and affects pH.

BIOFILTERS

Which size do you need?

Size from ammonia load. See biofilter sizing. Use a conversion rate verified for the carrier, temperature, water chemistry, oxygen supply and loading.

BIOFILTERS

Where it goes

Gravity-fedAfter the drum filter, flowing by gravity.
Pump-fedA pump supplies the reactor; confirm vessel pressure rating, water level and the approved arrangement.
BIOFILTERS

A new filter needs time to mature

See start-up and cycling.

BIOFILTERS

Moving bed, static media or trickle?

Moving bedStatic mediaTrickle filter
How it worksMedia moved by airFixed media under waterWater rains over media in air
OxygenFrom air bubblesOnly what water bringsStraight from air
CleaningSelf-cleaningNeeds rinsingLow
BIOFILTERS

Problems and what to check

Media floats in a layerToo little air or too much media.
Part of the media stands stillUneven air.
Nitrite stays highImmature or overloaded.
pH keeps fallingAlkalinity used up. Buffer.
Foam on the surfaceOrganics. Check skimming.
Media in the pondCheck the outlet screen.

Pureflow Bio equipment for this

MBBR biofilters →Moving bed biofilters.Standard drum filters (RDF) →Automatic solids removal.
PROJECT REVIEW

Check the biological assumptions

Use these questions to prepare a project brief or an operating review. Check an item only when the information has been recorded for your installation.

0 of 3 checked

This checklist is a working aid in the current page session, not a saved maintenance record.

QUESTIONS

Moving Bed Biofilters FAQ

Do MBBRs need cleaning?

Inspect the reactor, aeration and retention screens routinely; carrier motion does not make the complete system maintenance-free.

How much air does it need?

Enough to move all media gently.

Can I use it in cold water?

Yes, but bacteria are slower.

KEEP READING
Biological filters→Biofilter media→Biofilter sizing→Trickle filters→

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