Review on potential uses, cementing process, mechanism and syntheses of phosphate cementitious materials by the microbial mineralization method.

• Bio-phosphate minerals can be prepared by the MIPP, have cementation effect. • The bio-phosphate cement can consolidate the loose particles and heavy metals. • The bio-phosphate cement has important application prospect. The main mineralization process is hydrolysis of the organic phosphomonoester with the alkaline phosphatase produced by the Bacillus subtilis. The structural characterization of phosphate nanomaterials showed that the nanostructures of phosphate could be prepared by the microbial mineralization method. The nano-sized bio-BaHPO 4 and bio-BaNaPO 4, with an average size 100 nm, could be well synthesized in the supernatant liquid of the bacteria at the pH = 8 and 11, but the nano-sized bio-BaHPO 4 and bio-BaNaPO 4 were not prepared by the chemical method in the same conditions. The bio-Mg 3 (PO 4) 2 ·5H 2 O had a honeycomb-like structure, but the chem-Mg 3 (PO 4) 2 ·5H 2 O was irregular. The average particles size of the bio-Mg 3 (PO 4) 2 ·5H 2 O was less than the chem-Mg 3 (PO 4) 2 ·5H 2 O. The bio-Fe 3 (PO 4) 2 ·8H 2 O, bio-Ca 5 (PO 4) 3 (OH) and bio-CePO 4 could also be prepared by the microbial mineralization method, but the chem-Fe 3 (PO 4) 2 ·8H 2 O, chem-Ca 5 (PO 4) 3 (OH) and chem-CePO 4 could not be synthesized by a simple chemical reaction. Compared with the Sporosarcina pasteurii induced carbonate precipitation, the Bacillus subtilis induced the formation of phosphates that were more stable than carbonates in the weak acid environments. The Sporosarcina pasteurii induced carbonate precipitation produced a large amount of harmful ammonia, whereas the Bacillus subtilis induced the formation of phosphates that did not produce any harmful gases. According to the literature reported, the microbially-induced phosphate precipitation (MIPP) had the cementitious properties. The cementation mechanism was the bio-phosphates interact with pure quartz sand to form van der Waals bond in the sand columns. Therefore, the use of MIPP can not only apply to the preparation of functional materials, but also has potential applications in the removal of heavy metals, treatment of solid waste, consolidation of sandy soil, and so on. [ABSTRACT FROM AUTHOR]