Photofermentation of crude glycerol from biodiesel using Rhodopseudomonas palustris: Comparison with organic acids and the identification of inhibitory compounds

► Growth and H2 production by R. palustris on various carbon sources investigated. ► Saponified fatty acids identified as the inhibitory component of crude glycerol. ► Investigations into inhibition by glycerol, alcohols and salts conducted. ► Normal growth and H2 production on crude glycerol after treatment shown. ► Significant results in photofermenting crude glycerol to high purity H2.