MBBR for Pulp & Paper Wastewater

Pulp and paper mills discharge large volumes of warm, high-COD wastewater containing fibres, lignin and its derivatives, resin acids and colour. A portion of the COD — notably lignin — is recalcitrant, so it resists biodegradation. MBBR is widely used in this sector as a high-rate biological stage that removes the biodegradable COD compactly and reliably, handling the large flows and warm temperatures typical of mills.

High-rate Treatment of Large Flows

Fibres and solids are removed upstream to protect the carriers. The biodegradable COD is treated efficiently, often at high loading, while the recalcitrant lignin fraction and colour set a floor on the achievable effluent and may require a dedicated polishing step where strict colour or COD limits apply. The warm temperature of mill effluent generally supports biological rates, and nutrient dosing may be needed because these streams can be nutrient-poor relative to their carbon.

MBBR is frequently applied as a compact high-rate stage, either standalone or ahead of or alongside other biological treatment at the mill.

Pulp & Paper Design Context (indicative literature ranges — confirm per project)

Parameter	Typical Value	Unit	Notes
Dominant load	high COD	—	Lignin, resin acids, fibres
Recalcitrant fraction	lignin, colour	—	Sets effluent floor
Temperature	warm	—	Generally favours biology
Nutrients	often dosed	—	Carbon-rich, N/P-poor

Colour and Recalcitrant COD

Where a mill faces strict colour or COD consents, the recalcitrant lignin-derived fraction that biology cannot remove is addressed with a polishing step such as coagulation or advanced oxidation. Characterising the biodegradable-versus-recalcitrant split is central to setting a realistic target.

Frequently Asked Questions

Why is some pulp and paper COD hard to remove?

Lignin and its derivatives are recalcitrant — they resist biodegradation and contribute colour — so they pass through biology and set a floor on the effluent COD, sometimes needing a polishing step.

Is MBBR suited to large mill flows?

Yes. MBBR is often used as a compact high-rate stage that removes biodegradable COD reliably from the large, warm flows typical of pulp and paper mills.

Does pulp and paper wastewater need nutrient dosing?

Often. These streams can be carbon-rich but nitrogen- and phosphorus-poor, so nutrient dosing may be needed to maintain a healthy biofilm.

MBBR for COD Removal

High-COD Wastewater

Textile Wastewater

Complex Industrial Wastewater

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