An Experimental Investigation of Microbial-Induced Carbonate Precipitation on Mitigating Beach Erosion

Abstract

Microbial-induced calcium carbonate precipitation (MICP) has the potential to be an environmentally friendly technique alternative to traditional methods for sustainable coastal stabilization. This study used a non-pathogenic strain that exists in nature to experimentally investigate the application of the MICP technique on mitigating sandy beach erosion. First, the unconfined compressive strength (UCS) test was adopted to explore the consolidation performance of beach sand after the MICP treatment, and then model tests in a wave flume were conducted to investigate the MICP ability to mitigate beach erosion by plunger waves. This study also employed field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) to observe the crystal forms of MICP-treated sand after wave action. The results reveal that the natural beach sand could be consolidated by the MICP treatment, and the compressive strength increased with the increase in the cementation media concentration. In this study, the maximum compressive strength could be achieved was 517.3 kPa. The one-phase and two-phase MICP treatment strategies were compared of sandy beach erosion tests with various spray and injection methods on the beach surface. The research results indicate that the proper MICP treatment could mitigate beach erosion under various wave conditions; the use of MICP reduced beach erosion up to 33.9% of the maximum scour depth.

Assessment of the Composition Effect of a Bio-Cementation Solution on the Efficiency of Microbially Induced Calcite Precipitation Processes in Loose Sandy Soil

“…The MICP process occurs naturally in various situations and can be induced artificially under appropriate environmental and nutritional conditions in order to benefit from the good cementing qualities produced throughout the process [2]. MICP technology has been developed for various types of soil, such as sand [3], expansive soils [4], loess [5], and silt [6], and has been successfully applied in many engineering areas related to stability and erosion prevention, such as wind erosion resistance [7], mitigation of beach erosion [8], and rainfall erosion resistance [9]. The MICP technique is classified into six types depending on the pathway used, such as ureolysis, photosynthesis, denitrification, ammonification, sulfate reduction, and organic compound oxidation by bacterial metabolism [10], among which only denitrification and sulfate reduction occur under anaerobic conditions and are difficult to apply under unsaturated conditions in soil.…”

Bioprospecting Ureolytic Rock Bacteria for Calcium Carbonate Precipitation Inducer

“…There were two types of calcium carbonate precipitate morphology: rhombohedral and spherical. Rhombohedral crystals are characteristic of calcite, which has a more stable crystal form than the spherical form 47) . According to Reeksting et al, (2020) 20) , the variation in crystal morphology that each strain of ureolytic bacteria produced was impacted by the ureolytic activity, which had an effect on the precipitation rate.…”

Application of Microbial-Induced Calcium Carbonate Precipitation in Wave Erosion Protection of the Sandy Slope: An Experimental Study

“…Shahin et al [37] used a hydraulic model test to investigate the feasibility of MICP for preventing coastal erosion in shallow waters, and the results indicated that the MICP technique could control the coastal erosion of a 45 • sandy slope to within 5%. Tsai et al [38] indicated that the proper MICP treatment could mitigate sandy slope erosion under various wave conditions, and the MICP treatment could reduce sandy slope erosion up to 33.9% of the maximum scour depth. As for existing studies on the MICP protection of slope erosion [35][36][37][38], these model scales are too small to reflect the real cases, e.g., the boundary effect in small-scale tests is more obvious than that of the large-scale tests, and a small slope scale may lead to inaccurate sensor measurement in the tests, thus causing large test errors.…”

“…Tsai et al [38] indicated that the proper MICP treatment could mitigate sandy slope erosion under various wave conditions, and the MICP treatment could reduce sandy slope erosion up to 33.9% of the maximum scour depth. As for existing studies on the MICP protection of slope erosion [35][36][37][38], these model scales are too small to reflect the real cases, e.g., the boundary effect in small-scale tests is more obvious than that of the large-scale tests, and a small slope scale may lead to inaccurate sensor measurement in the tests, thus causing large test errors. In addition, the key parameters, e.g., the wave shape and the pore water pressure, have not been studied for the slopes with MICP treatments.…”