Lu and coworkers stress that phosphorus "plays a crucial role in the growth of plants and crops", "but the utilization of phosphorus resources faces two significant challenges. On the one hand, under natural conditions, phosphorus ore is non-renewable". According to Lu and coworkers, we are therefore facing a "phosphorus crisis" in human society. Since "phosphorus is easily discharged into the water through human production and daily life", we are at the same time facing a "phosphorus pollution" (see Lu et al, and references therein). Lu and coworkers are providing references about the applications of vivianite, "particularly in producing high-value products like lithium batteries" (Lu et al., mentioning , "the obtained vivianite can be used to produce high value-added products such as lithium batteries"). Moreover, vivianite "can be efficiently synthesized during the anaerobic fermentation of waste-activated sludge (WAS)". Lu and coworkers concentrate the research on the use of carbonaceous materials in vivianite formation; the researchers mention graphite, carbon nanotubes, and biochar, "as a more affordable, easily produced, and sustainable carbon material, [which] holds significant potential in accelerating electron transfer processes" (Lu et al., and references therein). Therefore, "understanding the vivianite synthesis system's response mechanisms after adding biochar is crucial for improving the efficiency of vivianite formation". About biochar, see Sparavigna and references therein.