Current status, gaps and challenges of rendering industries wastewater

The consumption of products of animal origin (PAO) has drastically increased in the last 50 years. Alongside, animal by-products' residues generation increased as they were generated during PAO processing. Rendering industries are the main route to add value to these residues, leading to a higher amount of raw material that increases production and residue generation, such as gaseous effluents and wastewater. Regarding rendering wastewater treatment, literature is still scarce on treatments and valorisation processes. In this context, this paper is the first review and bibliometric analysis of rendering wastewater, focusing on approaching treatment and valorisation processes proposed in the literature, pointing out its gaps and future perspectives. Biological and physicochemical processes are approached by literature. The majority of research papers addresses biological process, meanwhile recent literature focus on physicochemical processes. Literature indicates that whereas different streams of wastewater are generated in the rendering industry, the possibility of segregation plays a major role in the wastewater treatment plant (WWTP) configuration. Valorisation of the rendering wastewater can generate added value products, such as FOG-rich sludge (reprocessed as raw material), protein and biogas, besides treated water for irrigation, hygiene and vapour generation. Therefore, combining different steps of biological and physicochemical processes during the rendering wastewater treatment can enhance its efficiency, enabling its valorisation. [Display omitted] •The first review on rendering wastewater treatment and valorisation is presented.•Novel processes are pointed out to be studied.•Literature gaps around treatment and valorisation processes are explained.•Future perspectives considering highlighted processes are expressed.