Production of the polyhydroxyalkanoate biopolymer by Cupriavidus necator using beer brewery wastewater containing maltose as a primary carbon source

Recent technologies have been directed toward the use of inexpensive carbon sources like agricultural wastes and wastewaters in order to produce polyhydroxyalkanoates (PHAs) in a large commercial and industrial scaleand to reducehazardous pollutants. This study aimed to produce poly-3-hydroxybutyrate (PHB) from wastewater of the beer brewery industry using Cupriavidus necator. For this purpose, the experiments were performed at three steps to evaluate the effect of C/N and C/Pratios and industrial-grade maltose on biopolymer production. The batch system was chosen for the fermentation process and the alteration of bacterial growth and NH4+-N and PO43--P consumption were monitored at 24 h intervals. Maximum biopolymer production of 1.98 g L-1 and biomass yield of 0.45 g biomass/g consumed sugar were obtained at the ratio of C/N/P = 100:2:15 and maltose concentration of 40 g L-1. Besides, the highest biopolymer yield and volumetric productivity associated with the ratio of C/N/P = 100:2:15 were 0.28 g g(-1) and 0.022 g L-1 h(-1), respectively. Therefore, the C/N/P ratio of 100:2:15 and the maltose concentration of 40 g L-1 were selected as the optimum condition which then generalized to the raw wastewater. The assessment of experimental data showed the amount of produced biomass and biopolymer in the raw wastewater as 7.9 and 3 g L-1, respectively. However, it can be concluded that the beer brewery wastewater has a high extraordinary potential for PHB production which could be an appropriate and eco-friendly alternative for petroleum-derived plastics.