The transesterification of frying waste oil for biodiesel synthesis can provide crude glycerol contaminated by aldehydes, ketones, methyl esters, heavy metals, anions, and other impurities. This fact has become an environmental problem being a huge challenge to recovery the glycerol from biodiesel synthesis by using frying oil as feedstock. This study depicts a novel strategy to treat residual glycerol produced from the frying oil transesterification. Crude glycerol is subjected to one pre-purification process by using a cationic and condensed tannin derivative (a functionalized polymer with amino moieties in its structure). This polymer is used as an efficient coagulant/flocculant agent. After pre-purification step, the glycerol is purified following treatments by ion exchange resins and water evaporation. Glycerol-based samples (crude, purified and a standard) are characterized through chromatography-mass spectroscopy, atomic absorption spectrometry, infrared spectroscopy, and nuclear magnetic resonance (H-1 and C-13). The impurity content based on aldehydes, methyl esters, chloride and, heavy metals are significantly reduced/removed, imparting purified glycerol of technical grade (similar to 95 wt% purity). So, by combining both cationic tannin derivative and ion exchange resins, we can treat the crude glycerol obtained from the frying oil transesterification, following an eco-friendly and more economical process.