Volatile fatty acids (VFA) are proposed platform molecules for the production of basic chemicals and polymers from organic waste streams. In this study we developed a granular sludge process to produce VFA at high rate, yield and purity while minimizing potential operational costs. A lab-scale anaerobic sequencing batch reactor (ASBR) was fed with 10g l(-1) glucose as model substrate. Inclusion of a short (2min) settling phase before effluent discharge enabled effective granulation and very high volumetric conversion rates of 150-300gCODl(-1)d(-1) were observed during glucose conversion. The product spectrum remained similar at the tested pH range with acetate and butyrate as the main products, and a total VFA yield of 60-70% on chemical oxygen demand (COD) basis. The requirement for base addition for pH regulation could be reduced from 1.1 to 0.6mol OH- (mol glucose)(-1) by lowering the pH from 5.5 to 4.5. Solids concentrations in the effluent were 0.6 +/- 0.3g l(-1) but could be reduced to 0.02 +/- 0.01g l(-1) by introduction of an additional settling period of 5min. The efficient production of VFA at low pH with a virtually solid-free effluent increases the economic feasibility of waste-based chemicals and polymer production. Biotechnol. Bioeng. 2015;112: 2248-2255. (c) 2015 Wiley Periodicals, Inc.