OXYGEN UTILIZATION OF TRICKLING FILTER BIOFILMS

In-situ oxygen consumption rate (OCR) observations for trickling filte r biofilms under different hydraulic, substrate loading, and oxygen av ailability operating conditions are presented. OCRs were determined fo r sucrose- and dextrin-based synthetic feedstocks by growing biofilms on a 1.2-m deep section of 60-degrees cross-flow media that was enclos ed within a reactor vessel, sealing the reactor vessel to outside air entry, and observing the time rate of decrease in the reactor's oxygen partial pressure. The results indicate that OCRs increased proportion ately with increasing influent substrate concentrations for the 40 to 120 mg/L SCOD range, increased slightly or remained relatively constan t with increasing influent substrate concentrations for the 120 to 200 mg/L SCOD range, increased slightly with increasing DO saturation con dition for the 7.4 to 10.1 mg/L range, were affected by oxygen availab ility for influent substrate concentrations throughout the 70 to 175 m g/L SCOD range, increased with increasing hydraulic application rate f rom 2.4 to 4.9 m3/m2-h, and were slightly greater than predicted by cu rrently acknowledged models. Other observations include the following: measured OCRs were at least three times greater than those estimated from clean media oxygen-transfer testing; without liquid and feedstock application, biofilms consumed oxygen at 80-104% of their usual rate: and maximum biofilm oxygen consumption was almost-equal-to 680 mg/m2- h.