Treatment of piggery wastewater by USBF reactor with flexible - bed in anaerobic filter part

Abstract

In this study, an upflow sludge blanket filtration (USBF) model, which is a combination of suspended growth in upflow anaerobic sludge blanket (UASB) part and attached growth in anaerobic filter (AF) part is improved to enhance treatment efficiency of piggery wastewater by changing support media in AF part from fixed - bed to flexible - bed. Flexible – bed, made from Anox Kaldnes K1 media, allows for attachment of large amounts of highly active biomass. The USBF model made of acrylic had the work volume of 14 liters and the ratio of UASB/AF of 1/1. Organic loading rate (OLR) was increased from 1 to 10 kgCOD/m3 .day and corresponding hydraulic retention times (HRT) was reduced from 36 to 9.6 hours. The results showed that treatment efficiencies of COD and SS reached 92% and 93%, respectively at the optimum OLR of 6 kgCOD/m3 .day and the corresponding HRT of 16 hours. In the anaerobic filter part, the biomass concentration (VSS) was 3080 mg/L and the ratio of VSS/SS was 0.78 at the end of operation. The results also showed that biofilm attached on media surface of the flexible - bed was active and regular.