(4mf) Accumulation of Biopolymer in the Microalgae Chlorella sorokiniana Cultivated Under Petroleum-Derived Produced Water

Microalgae offer promising avenues for sustainable biomass production, with their ability to accumulate valuable biopolymer under diverse environmental conditions. Produced water, a byproduct of oil extraction, poses significant environmental challenges due to its high salinity, heavy metal content, and hydrocarbon pollutants. However, it also represents a potential nutrient source for microalgae cultivation, given its rich composition of organic and inorganic compounds. In this study, a freshwater microalgae Chlorella sorokiniana, was cultivated in photobioreactors having synthetic produced water (SPW) supplemented with synthetic municipal wastewater (SMW) to provide essential nutrients in controlled laboratory conditions. The photobioreactors were supplemented with SMW to create six different concentration gradients: 10%, 20%, 30%, 40%, 50%, and 100% PW. Growth kinetics of the microalgae were monitored alongside the accumulation of biopolymer, polyhydroxyalkanoate (PHA). Results indicate that, except for 100% PW, maximum biomass output after 8 days ranged from 278 mg/L to 1157 mg/L, where maximum biomass concentration was obtained for 20% PW. PHA was recovered from the Chlorella sorokiniana biomass using chemical extraction procedures. According to the results, biopolymer was obtained in all the experiments except 100% PW in a range of concentrations (39.20–65.98%, w/w DW). Maximum biopolymer was attained for 10% PW and categorized as polyhydroxybutyrate (PHB) by FTIR analysis. The results indicate a significant enhancement in the accumulation of biopolymer in Chlorella sorokiniana under petroleum-derived produced water cultivation. The obtained biopolymer can be utilized as a promising source of bioplastics as well as for a wide variety of applications.