Nitrate increases the capacity of an aerobic moving-bed biofilm reactor (MBBR) for winery wastewater treatment

Abstract

We used bench-scale tests and mathematical modeling to explore chemical oxygen demand (COD) removal rates in a moving-bed biofilm reactor (MBBR) for winery wastewater treatment, using either urea or nitrate as a nitrogen source. With urea addition, the COD removal fluxes ranged from 34 to 45 gCOD/m2-d. However, when nitrate was added, fluxes increased up to 65 gCOD/m2-d, twice the amount reported for aerobic biofilms for winery wastewater treatment. A one-dimensional biofilm model, calibrated with data from respirometric tests, accurately captured the experimental results. Both experimental and modelling results suggest that nitrate significantly increased MBBR capacity by stimulating COD oxidation in the deeper, oxygen-limited regions of the biofilm. Our research suggests that the addition of nitrate, or other energetic and broadly used electron acceptors, may provide a cost-effective means of covering peak COD loads in biofilm processes for winery or another industrial wastewater treatment. HIGHLIGHTS An aerobic MBBR for winery wastewater treatment was studied.; Kinetics and stoichiometry were determined for winery wastewater biodegradation.; COD removal fluxes in an aerobic MBBR doubled when nitrate was added.; Nitrate activates inner biofilm, where dissolved oxygen is limiting.; Nitrate supplementation may provide an effective means of treating seasonal peak loads in industrial wastewaters.;

Keywords

• biofilms
• bod removal
• denitrification
• kinetics
• modeling