Production of Bioagent for Calcium-Based Biocement

Abstract

Biocements and biogrouts are developing extensively as new materials alternative to cement and toxic chemical grouts. The most popular type of biocement is a mixture of urease-producing bacteria, urea and calcium salt. Thus, development of biotechnology to produce biomass of urease-active bacteria for large-scale biocementation is an important biotechnological task. Two strains of urease-producing bacteria, Yaniella sp. VS8 and Bacillus sp. VS1 that synthesized inducible and constitutive urease, respectively, were used in the present study. It was shown that low cost biomass of urease-active bacteria can be produced from the hydrolyzed excessive activated sludge of municipal wastewater treatment plant. The biomass of Yaniella sp. VS8 grown in this medium diminished the hydraulic conductivity of sand from 4.8×10-4 m/s to 5•10-8 m/s after several biotreatments with solution of 1.5 M urea and 0.75M СаCl2.

Preparing of Bio-Cement Mortar by Using Bacillus Licheniformis Bacterial Cells

“…Mechanism of Biocementation: Biocementation is a process of producing binding materials based on MICP mechanism [13]. Biocementation is a series of subsequent steps started with attachment of the cell of urease-forming bacteria to the particle surface, formation of a micro-gradient in the pH concentration of carbonate/bicarbonate at the cell attachment site as a result of urea hydrolysis by urease; and [10] the creation of calcite crystals that adhere to the particles surface [11], [14], [15].…”

Biocementation and bioclogging of sand using improved MICP techniques

“…For cost minimization, the costly protein-rich yeast extract media has been well deliberated to be replaced by alternative nutrients, including cheaper commercial milk powder, lysed activated sludge (Cheng and Cord-Ruwisch 2013) or tryptic soya broth (Stabnikov 2016). Also, with an additional low concentration of nickel, the cofactor of urease, urease activity can be enhanced (Bachmeier et al 2002).…”