Optimization of nickel nanoparticles concentration for biogas enhancement from green algae anaerobic digestion

Abstract The process of ship ballast water treatment and algae disaster management has produced a large amount of algae waste, and its disposal has become a key problem in the field of marine environmental protection. Algae waste has great potential to become a raw material for biogas production, and can comprehend multiple benefits of waste treatment and resource utilization. In order to increase the productivity characteristic of algae waste, this study is focused on introducing nickel nanoparticles (Ni NPs) in anaerobic digestion (AD) of green algae Enteromorpha. Optimization of Ni NPs was carried out by Response Surface Methodology (RSM). Batch experiments were conducted to optimize AD process of green algae at different temperature (25–45 °C), initial pH (5–9) and Ni NPs concentration range of (0.5–2 mg/L). Results showed that favourable concentration for Ni NPs is 1 mg/L whereas the temperature and initial pH of 35 °C and 7 had better effect on anaerobic digestion of green algae. The results showed that 1 mg/L Ni NPs produced highest biogas yield of 346 ml in comparison with other concentrations and control.