P-48 Improvement of semi-continuous methane production from marine macroalgae

Abstract

Stable semi-continuous culture was achieved with 10 wt% TS of undiluted brown algae as substrate. When TS content of substrate increased to 15 wt% at OLR of 1.7 g VS/kg/day, which was same OLR as cultivation using 10 wt% TS of substrate, and hydraulic retention time (HRT) of 68 day, methane production rate increased 1.3-fold compared with 10 wt% TS although salinity increased from 1.9 to 2.5 % NaCl equivalent. Thereafter, 20 wt% TS of substrate was used at an increased OLR of 2.3 g VS/kg/day under the same HRT, resulting in unstable methane production. Therefore, OLR can be possibly increased by using substrate concentrated to above 15 wt% TS but below 20 wt% TS or by using 15 wt% TS of substrate under shortened HRT.