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

A new cleaner technology for the recovery of poly(3-hydroxybutyrate) (PHB) from Alcaligenes eutrophus is reported. This involves continuously using the recycle-wastewater combined with small additions of surfactant and chelate to recover PHB, treating the final wastewater with hydrochloric acid and activated carbon when the purity of recovered PHB was decreased to less than 96%, which was called one round of recovery, and reusing the treated wastewater together with adding small amounts of surfactant and chelate to start 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 surfactant and chelate and the volume of discharged wastewater were reduced by using recycled wastewater. The purity of PHB was higher than 96%, and the recovery rate was near 90% under conditions of the ratios of surfactant and chelate to dry biomass were 0.0075 and 0.01, respectively, temperature 15 degreesC, pH 13 and 10 min recovery time. The wastewater could be recycled for four rounds, and the number of recovery times in each round was five. Further studies indicated that the surfactant and chelate benefited cell disruption, There was no obvious change in the viscosity average molecular weight (Mv) of PHB among the different stages of PHB cleaner recovery process. (C) 2001 Elsevier Science Ltd. All rights reserved.