Biochemical oxygen demand (BOD) measures the readily biodegradable organic load. Effluents from food processing, breweries, dairies and similar industries are often high in BOD and highly biodegradable. Because this load is largely biodegradable, MBBR can remove a high proportion of it — but the heavy load also drives a high oxygen demand, so aeration design is central to a high-BOD MBBR.
Handling Heavy Biodegradable Load
The fixed biofilm lets an MBBR carry a high biodegradable load and recover quickly from peaks, which is valuable for industries with batch or shift-based discharges. Removing high BOD consumes a large amount of oxygen, so the aeration system must both supply that oxygen and keep the carriers in circulation. In many cases the reactor is staged, with the first stage taking the bulk of the load and later stages polishing.
High-BOD industrial effluents can be nutrient-poor relative to their carbon content; supplementary nitrogen and phosphorus dosing is sometimes needed to sustain a healthy biofilm.
High-BOD Design Context (indicative literature ranges — confirm per project)
| Parameter | Typical Value | Unit | Notes |
|---|---|---|---|
| SALR — carbon duty | 5 – 15 | g BOD/m²·d | Higher for roughing stages |
| Oxygen demand | high | — | Drives aeration sizing |
| Nutrient balance | BOD:N:P | — | Dose N/P if carbon-rich — confirm per project |
| Staging | often multi-stage | — | Bulk removal then polishing |
Aeration and Nutrient Balance
Because oxygen demand scales with the BOD removed, blower capacity is a key design and operating cost for high-BOD duty. Checking the carbon-to-nutrient balance and dosing nitrogen or phosphorus where needed keeps the biofilm healthy and treatment efficient.
Frequently Asked Questions
Is MBBR good for high-BOD effluents?
Why might nutrient dosing be needed?
What is the difference between BOD and COD duty?
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