A full-scale study of external circulation sludge bed (ECSB) system for anaerobic wastewater treatment in a whiskey distillery

Waste liquid streams from distillery were a hurdle in conventional wastewater treatment due to extreme high chemical oxygen demand (COD) and fluctuating feed conditions. A recently commissioned full-scale external circulation sludge bed (ECSB) was applied at a malt whiskey distillery in northeast Taiwan. Start-up of the new ECSB system, which has a total volume of 490 m(3) with diameter of 6.55 m (phi) and height of 15.9 m (H), was performed by gradual increasing influent flow rates from zero to the design value of 300 m(3) day(-1) in the first 90 days. In the subsequent 204 days, both influent flow rates (0-389 m(3) day(-1)) and COD concentrations (2.8-18.1 kg L-1) were highly fluctuated due to diverse batches from the distillery. However, effective bioremediation (COD removal 95.1 +/- 2.4%) and biogas production (1195 +/- 724 L day(-1)) were achieved in this system. Intensively, the Imhoff tests were carried out and shown the settled solids concentration by 0.5 +/- 0.4 mL L-1, while size distributions of granular sludge were analyzed and observed by SEM-EDS. In addition, developments of the anaerobic systems (including lab, pilot, and full scale from the simplest reactor to the latest ECSB) applied in whiskey wastewater treatment were reviewed with their operational parameters for comparing performances of various anaerobic systems. In general, real-time monitoring and feasible operation strategies were critical to successfully run the system by producing clean energy simultaneously. It provides more economically attractive and sustainable-to-adopt ECSB not only an end-of-pipe process but also a bioresource technology.