Fungal treatment of corn processing wastewater in an attached growth system

Corn processing wastewater was treated in an attached growth system of Rhizopus oligosporus fungi. The effects of hydraulic retention time (HRT) and plant-based components in the support media were evaluated in 1 L reactors under non-aseptic conditions. Plastic composite support (PCS) tubes, composed of 50% (w/w) polypropylene (PP) and 50% (w/w) agricultural products were used as support media or, as a test, PP only. A maximum chemical oxygen demand (COD) removal of 78% was achieved at a 5 h HRT with a biomass yield of 0.44 gVSS/gCOD_removed. The biomass yield increased to 0.48 gVSS/gCOD_removed while COD removal reduced to 70% at a 2.5 h HRT. Competitive bacterial growth was reduced at the shorter HRT. A lower HRT of 1.25 h led to biomass wash out from the reactor. Significantly lower COD removal of 28% and biomass yield of 0.19 gVSS/gCOD_removed were observed in a biofilm reactor with PP tubes alone, indicating that the agricultural components in PCS media were essential for better biofilm formation and organic removal.