Transformative approaches to produce PHAs from waste streams: a brief review

Throughout their existence, plastics made from petroleum have been associated with increasing environmental problems, such as pollution, accumulation in terrestrial and marine environments, and the release of greenhouse gases. To address the present environmental concerns, creating and producing eco-friendly polymers has received much attention in the industrial and research communities over the past ten years. The current review focuses on one of the beneficial products obtained after the waste treatment. The biodegradable polymer, Polyhydroxyalkanoates (PHAs), is synthesized from the variable organic materials collected during the waste aerobic and anaerobic treatment. PHAs with short-chain-length (scl-PHA) and medium-chain length (mcl-PHA) are commonly synthesized with different bacterial strains as a factor to determine the chain length. Researchers studied various methods to find the optimum parameters and yield of PHAs while considering the cost. It can be concluded that pH 7 and 60⁰C are the optimum conditions for bacteria pretreatment to obtain a high conversion of PHAs. Furthermore, one of the potential wastes, Palm Oil Mill Effluent (POME) obtained from palm oil production, was highlighted since Malaysia is the world's second-largest palm oil industrial player. The abundance of POME becomes highly toxic effluent and causes water pollution. Hence, POME can be manipulated to play an important role as one of the feedstocks for PHAs. This renewable PHAs biopolymer can solve the plastic degradation and the pollution caused by conventional polymers. The continuing improvement of PHAs was extensively examined to fulfill the world PHAs market demand.