From wasted ferric sludge to valuable waste: a systematic review using the knowledge development process—constructivist method

This article aims to carry out a structured systematic review of the alternatives adopted to transform ferric sludge into an attractive and viable resource, covering the period from 2015 to 2019. To assist in this knowledge construction process, the knowledge development process–constructivist ( ProKnow-C) intervention tool was used to select relevant articles, identify the characteristics of these publications, and critically analyze them. The final bibliographic portfolio (FBP) obtained for the research topic consisted of 15 articles. The most prominent journal within the FBP and in terms of references is the Chemical Engineering Journal, while the most relevant articles on the topic are those carried out by S. Guo et al. (2017) and H. Zhang et al. (2018). The most frequent alternative examined in the articles was the transformation of ferric sludge into a catalyst to be used in the heterogeneous Fenton reaction. Another promising alternative was the use of ferric sludge in anaerobic biological digestion as a way to enrich iron-reducing bacteria and also the use of catalysts obtained from the association of pyrolyzed biomass with ferric sludge. In all articles, there was no use of artificial UV radiation or the use of renewable energy sources (solar energy) in catalytic processes, which characterizes a potential line of investigation for future studies.