Operational Stability of a Horizontally Baffled-Anaerobic Reactor for Diluted Swine Wastewater in the Tropics

Abstract

ABSTRACT DEVELOPMENT of a low-cost, simple and stable anaerobic reactor treating diluted swine wastewater in the tropics was the main objective of this study. A horizontal-baffled reactor with a liquid volume of 20 L was tested at 30 C. Supernatant of settled swine wastewater having TCOD and SS concentrations under 5 g/L and 0.5 g/L, respectively, was used as feedstock. This reactor was tested for its ability to withstand shock loading and for its long term operational behavior at certain loading rates and hydraulic retention times (HRT). When operated over a 6 month period with a 2.5 day HRT and a loading rate of 1.8 g TCOD/L/day, a TCOD removal efficiency of 75% and methane production rate of 0.266 L/L/day were achieved. The reactor was also capable of tolerating a short-sharp shock loading (100% for 24 h at 5 days HRT) in terms of TCOD removal efficiency. Longer and higher levels of shock loading could be detrimental. At a lower HRT (2 days), the reactor would tolerate in terms of methane production rate up to a 200% increase in flowrate for 24 h. Recovery took no more than four days after the shock load of 200% was released. Detailed design and operational criteria were developed including level of quantitative shock loading which could be tolerated and recovery period which could be required after shock load.