Topic Area: 12c. Biocementation

Formatted Title:

The Impact of Various Additives on Bacterial Adsorption, Ammonia Removal, and Compressive Strength for MICP

Background/Objectives:

Microbially induced calcite precipitation (MICP) utilizes ureolytic bacteria, such as Sporosarcina pasteurii, to hydrolyze urea into ammonium and carbonate ions, which react with calcium to form calcium carbonate (CaCO₃). The process has various applications, including soil stabilization, concrete repair, dust control, and immobilization of heavy metals. MICP is influenced by factors such as bacteria concentration, pH, and calcium/urea levels. Additives such as (bio)polymers, fibers, and minerals can enhance bacterial adsorption, increase the strength of treated soil, and immobilize ammonium, helping to reduce the environmental impact of ammonium release.

Approach/Activities:

The influence of nine different additives (Ca-bentonite, Na-bentonite, clinoptilolite, natrolite, limestone, marl clay, concresol, secursol, and activated carbon powder) on bacterial adsorption, ammonium immobilization, and the resulting strength was investigated in quartz sand columns. To each quartz sand, 3% (w/w) of the respective additive was added. An experimental setup was developed to assess bacterial adsorption in sand columns, with ammonium immobilization by each additive also being tested. This setup allowed for a detailed analysis of the effects of the additives on both bacterial adsorption and ammonium retention within the sand columns. The columns were stored at 40°C for two weeks. To quantify the changes in strength, uniaxial compressive strength (UCS) tests were then performed on the columns.

Holger Maurer

Affiliation

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The Impact of Various Additives on Bacterial Adsorption, Ammonia Removal, and Compressive Strength for MICP