Scalable recovery of polyhydroxyalkanoate (PHA) from a mixed microbial culture via a novel acidification-NaClO digestion process

Polyhydroxyalkanoate (PHA) is a kind of cellular biopolymers, and a renewable alternative to conventional plastics. To promote low-cost PHA production, this study developed a simple and scalable process to recover this polymer from a phenol-fed mixed culture. Cultures containing >50 % PHA were first acidified then treated with NaClO, leading to digestion of cellular materials by HClO. NaClO dosage, HCl/NaClO ratio, and treatment time were tested for their effects on product Purity and Recovery rate. Compared with NaClO alone which obtained 55–74 % Purity and 57–73 % Recovery, acidification improved the extraction efficiency to 62–83 % Purity and 75–97 % Recovery of cellular PHA. Statistical analysis was performed on dosage, ratio and treatment time. The chemical cost of obtaining 1 kg pure PHA ranged $7–10, but can be greatly reduced by applying a denser culture. However, HClO reduced the molecular weight of the PHA products, which needs to be addressed in future studies.