Sequential operation of a hybrid anaerobic reactor using a lignocellulosic biomass as biofilm support

• Hybrid anaerobic reactor operated sequentially to treat liquid and solid waste.
• Lignocellulosic biomass used as both carrier support and substrate.
• High treatment efficiency during fast start-up and restart-up phases.
• Acclimation phase depends of the soluble fraction of lignocellulosic support.
• During non-feeding period, biofilm conserved its biological activity.

Agro-industries are facing many economic and environmental problems associated with seasonal generation of liquid and solid waste. In order to reduce treatment costs and to cope with seasonal variation, we have developed a hybrid anaerobic reactor operated sequentially by using lignocellulosic biomass (LB) as biofilm carrier support. Six LBs were tested to evaluate the treatment performance during a succession of two start-up periods, separated by a non-feeding period. After a short acclimation phase of several days, all the reactors succeeded in starting-up in less than 1 month to reach an organic loading rate of 25 gCOD L−1 d−1. In addition, they restarted-up successfully in only 15 days after a 3 month non-feeding period, indicating that biofilms conserved their biological activities during this last phase. As a consequence, the use of LB as a biofilm support gives the potential to sustain seasonal variations of wastewater loads for industrial application.