DEVELOPMENT OF SOLIDIFIED CULTIVATING SOIL BLENDED WITH WASTE WOODY BIOMASS PREPARED BY THE CEMENTATION TECHNIQUES

Abstract

Bio-cementation is well known as an environmentally friendly technique. It is studied for mitigating liquefaction, reducing dust, and increasing ground strength. This technique has been considered for use in the ground, but it is important to reduce ammonia (NH₃) and ammonium ions (NH₄⁺) generation. On the other hand, these by-products have the potential to act as beneficial nutrient sources in agricultural applications. We aim to develop a solidified cultivating soil using generated ammonium ions (NH₄⁺). Additionally, the importation of peat moss, a principal material of solidified cultivating soil, has declined due to the depletion of natural resources, prompting the search for environmentally sustainable alternative substrate materials. In this study, we conducted solidification and germination tests using EICP as a solidification method, which, unlike other bio-cementation techniques, does not require microbial cultivation, and using waste woody biomass such as bamboo powder and coco peat. Additionally, we investigated the collapse index of solidified cultivating soil, as well as the effects of ammonium nitrogen on solidification and germination. The results show that the solidification strength, represented by the collapse index, was enhanced with increased injection frequency at lower cementation concentrations (0.1 M and 0.25 M). At a concentration of 0.5 M, the solidification was sufficiently strong even with four injections. The germination rate increased as the molar concentration of cementation solution decreased. These results suggest that CaCO₃ cementation, when optimized in terms of concentration and injection frequency, holds promise for developing sustainable solidified cultivating soil.