Separation and purification technologies in polyhydroxyalkanoate (PHA) manufacturing: A review
Eunkyung Cho, Hyerim Eam, Jaewook Myung, Youngbin Baek
Abstract
Polyhydroxyalkanoate (PHA), a biopolymer synthesized by various microorganisms, is a sustainable alternative to petroleum-derived plastics, which is a biodegradable, biocompatible, and non-toxic biopolymer. In the PHA downstream process, recovery methods are generally categorized into biochemical and mechanical approaches, and the separation methods include precipitation, centrifugation, and evaporation. PHA exhibits considerable variability based on the type of cell culture, recovery or separation method, and material used. On the other hand, most high-purity PHA is obtained by combining biochemical recovery and precipitation using solvents or chemicals (> 95.4% on average). In particular, additional purification, such as redissolution or pretreatment, is essential to meet the purity standards for medical use. Endotoxin levels below 0.5 of 0.06 endotoxin units/mL are required. Consequently, most PHA downstream processes rely on chemicals with negative economic and environmental impacts because of their handling and treatment. Therefore, analyzing these manufacturing processes through a life cycle assessment is important for understanding their impacts. This paper discusses the overall technique for the downstream process of PHA and highlights the need to develop and optimize environmentally friendly and cost-effective methods, such as mechanical approaches, to produce high-value products to meet the required standards for various applications.