Start-up of dry semi-continuous OFMSW fermentation for methane production

This work proposes a strategy for start-up of dry semi-continuous reactors for methane production without using adapted inoculum. Using OFMSW as substrate, three reactors operating at 35 degrees C were used. Experimentation consisted in start-up, adjusting operational parameters (80 days) and, after start-up was successful, semi-continuous feeding under different organic loading rates (another 80 days). After the first 22 days, to control acidification, feeding was stopped. On day 42, slow feeding was restarted and, after day 50, the reactors produced methane under stable conditions and, after day 70, semicontinuous maximum feed was achieved with maximal methane production. Although the values for methane production vary between 339 and 333 NL kgVS1, the statistical analysis indicates indeed significant differences. With increasing organic load, methane production rate increased from 1.89 to 2.50 m(3) m(-3) d(-1) and volatile solids removal from 50 to 59%. According to the results, a successful start-up is possible under slow gradual feeding increase using alkalinities and VFA as monitoring parameters.