Valorization of fish waste for sustainable biofuel production: A case study in Ghana

Abstract

Fish processing plants generate significant waste annually, which harms the environment. To tackle this, the waste can be converted into biofuel, pharmaceuticals, fertilizer, and animal feed. Biofuels, specifically biogas and biodiesel, are emphasized for their eco-friendly properties that help combat global warming. The study focuses on producing biodiesel through transesterification and biogas via anaerobic digestion of fish waste. Analyses of the rate constant (K), activation energy (Ea), entropy (ΔS), enthalpy (ΔH), and Gibbs free energy (ΔG) at varied temperatures show highest Ea, K, ΔH, and ΔS values of 60.74 kJ/mol, 31.43 s−1, 66.01 kJ/mol, and 30.99 kJ/mol K, respectively. The biodiesel was also characterized by Fourier transform infrared (FTIR) spectroscopy and kinematic viscosity. Additionally, the properties; relative density, viscosity, oxidation stability, pour point, cloud point, flash point, and cetane number were found to be 0.669, 5.090 mm2s−1, >7, −7 °C, 0.999 °C, 151 °C, and 51, respectively. Biogas production using varying ratios of fish waste and cow dung (1:1,1:2, 1:3, and 1:4) indicates that a 1:4 ratio yields optimal results with 69% methane (CH4) and 21.5% carbon dioxide (CO2), suitable for scalable biogas production. The process is efficient at a neutral pH (7.1–7.3) and 27 °C, offering a viable solution to reduce fish waste pollution while generating renewable energy. Finally, a proposed model of a biodigester for optimum biogas production is discussed.