After the accident at the Fukushima Dai-ichi Nuclear Power Station, a large amount of contaminated water was treated using several decontamination systems with different natures of adsorbents and chemicals. The resulting wastes, called Fukushima Effluent Treatment Wastes (FETW), were stored at the Fukushima Dai-ichi site. Vitrification could be the most promising treatment method to package these wastes. The consortium gathering CEA, Orano, ECM Technologies and ANDRA, implemented an in situ, robust, simple and versatile In-Can vitrification process, the DEM&MELT technology. Since 2018, the applicability of this technology for FETW treatment and conditioning has been evaluated. In 2021–2022, studies focused on one particular waste, coming from the ALPS system (Advanced Liquid Processing System-Multi Radionuclides Removal) generating around 70%vol. of FETW. This waste is composed of two co-precipitation slurries: one mainly composed of iron hydroxide, and one of calcium carbonate and magnesium hydroxide. The purpose of this article is to highlight the feasibility of ALPS slurries vitrification with DEM&MELT, relying on tests performed from laboratory-scale to full-scale. Macroscopically homogeneous glasses were produced using the DEM&MELT demonstrator, with a waste loading of 60 wt.% (expressed as waste dry mass) and microstructural analyses were performed. It gives promising results for FETW conditioning with the DEM&MELT process.