Start-up of anaerobic digestion of source-sorted organic municipal solid waste in the absence of classical inocula

This study investigates the start-up and operation of bench-scale anaerobic digesters treating the source-sorted organic fraction of municipal solid waste in the absence of mesophilic inocula. The experimental program consisted of starting up a digester with two consecutive interventions implemented to approach steady state. While start-up was relatively slow, re-inoculation with cattle manure together with effluent dilution reduced the acclimation period and achieved better stability and effectiveness, accommodating a feeding rate at an OLR = 2.03 kg total volatile solids (TVS) m^-3 day^-1 and an equivalent hydraulic retention time (HRT) = 148 days. The latter highlights the long duration that should be taken into consideration in the design and start-up of anaerobic digestion systems for municipal solid waste, in countries where this system is not established, before reaching optimal steady-state conditions.