Anaerobic treatment of beet waste in a stationary fixed-film reactor

Abstract

Laboratory scale, downflow stationary fixed-film reactors with polyester cloth support and a surface-to-volume ratio of 86 m 2 m −3, operated continuously at 35°C, were capable of treating red beet wastewater with an organic strength between 5000 and 15 000 mg COD liter −1, at up to 87% COD removal efficiency. Organic loadings of up to 24 kg COD m −3 day −1 were achieved with COD removal rates of up to 16 kg COD m −3 day −1 and methane production rates exceeding 4 m 3 m −3 (reactor volume) day −1. Loadings of 30 kg COD m −3 day −1 and HRT of 5 h were achieved without process failure. The actual amount of waste organics converted and methane gas produced increased with increased loading, even though COD removal efficiencies decreased. A wide range of waste organic strengths could readily be treated but maximum methane production and COD conversion rates would be achieved with increased waste organic strength. Biomass yield increased with increased organic loading and was slightly influenced by waste organic strength.