Potential of Using Dual‐Media Biofilm Reactors as a Real Coffee Industrial Effluent Pre‐Treatment

Abstract

The coffee processing industry produces toxic and low biodegradable effluent, which can pollute water bodies. A pre‐treatment study on coffee effluent using a dual‐media biofilm reactor (DM‐BR) containing sand and Hexafilter (HEX) was conducted alongside a control biofilm reactor (C‐BR) containing sand media. The novelty of this study lies in the use of dual media in biofilm reactor (DM‐BR) for real coffee effluent treatment, where these processes were used individually in previous studies. The performance of DM‐BR and C‐BR in treating coffee effluent were investigated at different hydraulic retention times (HRTs), 24, 48 and 72 h, and the degrading bacteria were iden-tified. Both biofilm reactors were inoculated with a recycled paper mill‐activated sludge and accli-matised for 97 days. The DM‐BR displayed the highest removal of chemical oxygen demand (COD) and NH4+‐N at 47% and 38%, respectively, within 48 h of HRT, whereas colour and tannin–lignin reached maximum average removal of 21% and 29%, respectively, at 24 h of HRT. The combination of sand and HEX media in a system showed COD and NH4+‐N removal improvement at 48 h of HRT and encouraged a variety of bacterial species growth. Bacterial characterisation analysis revealed Proteobacteria to be dominant.