The　start-up　and　granulation　in　a　lab-scale　Anaerobic　Sequencing　Batch　Reactor　(ASBR)　fed　with　synthetic　glucose　wastewater　were　investigated.　Sludge　granulation　proceeded　after　110　days　operation　and　was　completed　in　approximately　140　days.　Scanning　electron　microscope　images　showed　that　filamentous　bacteria　like　Methanosaeta　are　abundant　in　the　granule　and　exhibit　in　a　uniform　structure.　The　growth　of　Methanosaeta　can　predominate　even　if　the　acetate　concentration　is　high　in　the　ASBR.　Short　filamentous　bacteria　are　observed　in　the　effluent.　Batch　tests　showed　that　the　composition　of　these　filamentous　microorganisms　included　fermentative,　syntrophic　acetogenic　and　methanogenic　bacteria,　with　an　ecology　similar　to　that　of　granular　sludge.