Enzyme-Induced Carbonate Precipitation: Scale-Up of Bio-Cemented Soil Columns

During large earthquake events where bending moments within soil cements are induced, the tensile strength of cemented soil may govern the deformational behavior of improved ground. Several studies have been conducted to assess the tensile strength of artificially cemented sands that use Portland cement or gypsum; however, the tensile strength of microbially induced carbonate precipitation (MICP)-treated sands with various particle sizes measured through direct tension tests has not been evaluated. MICP is a biomediated improvement technique that binds soil particles through carbonate precipitation. In this study, the tensile strength of nine specimens were measured by conducting direct tension tests. Three types of sand (coarse, medium, and fine) were cemented to reach a heavy level of cementation (e.g., shear wave velocity of ∼900 m/s or higher). The results show that the tensile strength varies between 210 and 710 kPa depending on sand type and mass of carbonate. Unconfined compressive strength (UCS) tests were performed for each sand type to assess the ratio between tensile strength and UCS in MICP-treated sands. Scanning electron microscopy (SEM) images and surface energy measurements were used to determine the predominant failure mode at particle contacts under tensile loading condition.

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Studies on parallel seismic testing for integrity of cemented soil columns

Journal of Zhejiang University SCIENCE A ◽

10.1631/jzus.2007.a1746 ◽

2007 ◽

Vol 8 (11) ◽

pp. 1746-1753 ◽

Cited By ~ 9

Author(s):

Da-zhi Huang ◽

Long-zhu Chen

Keyword(s):

Soil Columns ◽

Seismic Testing ◽

Cemented Soil

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Mathematical modelling and simulation of an industrial scale fluidized bed reactor for anaerobic wastewater treatment – scale-up effect on pH-gradients

Water Science & Technology ◽

10.2166/wst.1997.0594 ◽

1997 ◽

Vol 36 (6-7) ◽

pp. 219-227 ◽

Cited By ~ 3

Author(s):

Alexander Schwarz ◽

Marek Mösche ◽

Ahrend Wittenberg ◽

Hans-Joachim Jördening ◽

Klaus Buchholz ◽

...

Keyword(s):

Wastewater Treatment ◽

Scale Up ◽

Fluidized Bed Reactor ◽

Industrial Scale ◽

Carbonate Precipitation ◽

Biological Degradation ◽

Calcium Carbonate Precipitation ◽

Ph Gradients ◽

Anaerobic Wastewater Treatment ◽

Simulation Results

A mathematical model of anaerobic wastewater treatment in an industrial scale fluidized bed reactor (FBR) is presented together with simulation results for reactors in lab-scale (1 l) and industrial scale (500 m3). The model was developed to study the effect of scale up on the anaerobic wastewater treatment in FBRs by examining the interactions between biological degradation and the physico-chemical environment upon the outcome of this process. Material balance equations for substrates and products in gas and liquid phase are basis of the model. Hereby, the following effects were taken into account: biological degradation steps, convection and dispersion, chemical equilibria and calcium carbonate precipitation under consideration of ion activities. Model extensions are discussed, for example the calcium carbonate precipitation and the pH-dependency of degradation reactions. Simulation results show the strong impact of reactor performance on axial pH-gradients and thus on process stability in dependence of reactor scale. In this context the crucial role of the precipitation reaction together with the substrate degradation und carbon dioxide production reactions on local pH-values in the system is illustrated.

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Mid-scale biocemented soil columns via enzyme-induced carbonate precipitation (EICP)

SOILS AND FOUNDATIONS ◽

10.1016/j.sandf.2021.09.001 ◽

2021 ◽

Author(s):

Kimberly K. Martin ◽

Hamed Khodadadi Tirkolaei ◽

Edward Kavazanjian

Keyword(s):

Carbonate Precipitation ◽

Soil Columns

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NiAl precipitation in Fe-12w/o Cr-5w/o Ni-4w/o Al

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007480x ◽

1983 ◽

Vol 41 ◽

pp. 202-203

Author(s):

L.E. Murr ◽

J.S. Dunning ◽

S. Shankar

Keyword(s):

Solid Solution ◽

Stainless Steel ◽

Stainless Steels ◽

Alloy Composition ◽

Chromium Content ◽

Scale Up ◽

Optical Metallography ◽

Property Evaluation ◽

310 Stainless Steel ◽

Microstructural Studies

Aluminum additions to conventional 18Cr-8Ni austenitic stainless steel compositions impart excellent resistance to high sulfur environments. However, problems are typically encountered with aluminum additions above about 1% due to embrittlement caused by aluminum in solid solution and the precipitation of NiAl. Consequently, little use has been made of aluminum alloy additions to stainless steels for use in sulfur or H2S environments in the chemical industry, energy conversion or generation, and mineral processing, for example.A research program at the Albany Research Center has concentrated on the development of a wrought alloy composition with as low a chromium content as possible, with the idea of developing a low-chromium substitute for 310 stainless steel (25Cr-20Ni) which is often used in high-sulfur environments. On the basis of workability and microstructural studies involving optical metallography on 100g button ingots soaked at 700°C and air-cooled, a low-alloy composition Fe-12Cr-5Ni-4Al (in wt %) was selected for scale up and property evaluation.

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