Valorization of fish processing industry waste for biodiesel production: Opportunities, challenges, and technological perspectives

The fish industry is one of the fastest-growing industries in the world, which generates massive waste, and its unsafe disposal may pose severe health and environmental hazards. Thus, the valorization of fish waste has attracted the scientific community's attention due to its dual benefits of waste management and resource recovery. This waste has been reported as a suitable feedstock for various industrial uses such as biodiesel, biogas, animal feeds, dietary foodstuffs, food packaging, cosmetics, and catalysts. Fish waste for biodiesel production has become attractive due to its rich oil content. There are some significant limitations of using fish waste for biodiesel production, such as oil content and quality variations depending on the fish type and processing methods. Despite this, fish waste remains a promising feedstock due to the presence of more easily biodegradable organic compounds than other conventional lignocellulosic substrates. Recently, a few industries have also implemented fish oil technology for biodiesel production at a demonstration scale to establish a biorefinery. However, biodiesel production from fish wastes is challenging due to different factors, such as finding efficient and economically viable techniques to extract fish oil and transesterification. This review work has intended on the prospects and challenges of the potential of fish processing wastes to convert into biodiesel. Different extraction procedures, factors affecting transesterification, characteristics of biodiesel, and industrial opportunities have been comprehensively discussed.