Cleaner recovery of poly(3-hydroxybutyric acid) synthesized in Alcaligeneseutrophus

A new cleaner technology for the recovery of poly(3-hydroxybutyrate) (PHB) from Alcaligenes eutrophus is reported. This involves continuously using th e recycle-wastewater combined with small additions of surfactant and chelat e to recover PHB, treating the final wastewater with hydrochloric acid and activated carbon when the purity of recovered PHB was decreased to less tha n 96%, which was called one round of recovery, and reusing the treated wast ewater together with adding small amounts of surfactant and chelate to star t another round of PHB recovery. This paper focuses on the determination of suitable surfactant and chelate dosage, and how many times the wastewater might be utilized. A high purity of PHB was obtained and the required surfa ctant and chelate and the volume of discharged wastewater were reduced by u sing recycled wastewater. The purity of PHB was higher than 96%, and the re covery rate was near 90% under conditions of the ratios of surfactant and c helate to dry biomass were 0.0075 and 0.01, respectively, temperature 15 de greesC, pH 13 and 10 min recovery time. The wastewater could be recycled fo r four rounds, and the number of recovery times in each round was five. Fur ther studies indicated that the surfactant and chelate benefited cell disru ption, There was no obvious change in the viscosity average molecular weigh t (Mv) of PHB among the different stages of PHB cleaner recovery process. ( C) 2001 Elsevier Science Ltd. All rights reserved.