ABSTRACT
32Polyhydroxyalkanoates or PHAs are linear polyesters produced in nature by bacterial fermentation of sugar or lipids. The polyester is extracted and purified from the bacteria by optimizing the conditions of microbial fermentation of sugar or glucose. The simplest and most commonly occurring form of PHA is the fermentative production of poly-beta-hydroxybutyrate (poly-3-hydroxybutyrate, P3HB), which consists of 1000-30,000 hydroxy fatty acid monomers. The biosynthesis of PHA is usually caused by certain deficiency conditions (e.g., lack of macro-elements such as phosphorus, nitrogen, trace elements, or lack of oxygen) and the excess supply of carbon sources. In this work, pure oxygen was introduced in wastewater by a 40-l pure O2 container. Microorganisms receiving pure O2 grow quickly. By submerged porous diffusers and air nozzles, pure O2 was inserted to an aeration tank in transient flow condition. An activated sludge system (anaerobic and aerobic) continuously acts as a source of primary sludge. Anaerobic and aerobic activated sludge reactors were used to supply the required raw sludge. The important results in this work were to decrease BOD5 amount equal to 80–90% and the industrial production of PHA to produce plastics, which are biodegradable and are used in the production of bioplastics.
