Nickel ferrite nanoparticles catalyzed dark fermentation of dairy wastewater for biohydrogen production

Abstract

Biohydrogen production from wastewater is a new, low cost, sustainable energy development. In this study, dark fermentation, as a type of biological production of biohydrogen, was carried out using NiFe2O4 nanoparticle catalysts. Implementing the Central Composite Design model, the operational parameters including temperature, pH, and nanoparticle dosage were optimized. According to the spectroscopic and microscopic analyses, NiFe2O4 nanoparticles were successfully synthesized. The highest biohydrogen amount, i.e., ~241.3 mL, was obtained at 36 °C, 300 mg/L catalyst dosage, pH 6.5, and within the time range of 12 to 24 h. The biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were measured to be 153 and 87 mg/L, respectively, which were 97.5 and 83.6 % lower than their initial values. The NiFe2O4 nanoparticles could properly act as a catalyst for the dark fermentation process and promote the expression of the hydrogenase enzyme in bacterial cells, thereby producing a higher amount of biohydrogen.