Is It Possible to Produce Polyhydroxyalkanoate (PHA) Bioplastics of Consistent Composition from Organic Wastes? A Review

The main aim of this paper is to address the available literature on the issue of controlling the composition of polyhydroxyalkanoates (PHAs) during their production from organic wastes and if possible, provide a complete strategy to achieve consistent composition. Improvement in the handling of single-use packaging can result in tangible results in the quality of everyday life and the reduction of pollution. PHA bioplastics are candidate materials for many applications in the packaging sector. The cost of production of PHA bioplastics can be reduced with the use of organic waste streams as feedstocks. However, variations in the composition of the feedstock, result in variations in the composition of the final product. Feasibility of organic wastes utilization to produce PHA bioplastic depends on the ability to produce a consistent product-material. In this study, we focus on methods developed and tested to produce consistent composition and properties of PHA bioplastics from organic wastes. Numerous studies show that composition control can be established without affecting the global productivity and yield. The critical stages for composition control are the stages of feedstock selection, feedstock storage, and acidogenic fermentation. Fine tuning of the PHA composition is possible by mixing or synthetic feed in the stages of accumulation and extraction. Strategies for minimizing synthetic feed are suggested for process viability. Though various studies have shown that it is possible to obtain a consistent PHA material from organic wastes, strategies need to be developed to achieve consistency without affecting productivity and yield.