厨余垃圾蛋壳与贝壳在MICP技术中的应用研究

Study on Utilization of Eggshell and Scallop Shell in Microbial Induced Calcium Carbonate Precipitation

微生物诱导碳酸钙(MICP)是一种环保可持续的地基改良技术,该技术中常常需要消耗大量化学分析级试剂,诸如尿素、钙盐等,对环境等造成一定的不良影响。该文从环保角度出发,基于废弃资源再利用理念,选取了蛋壳和贝壳2种再生钙源并以化学钙源硝酸钙作对照,通过渗透试验、干密度试验、无侧限抗压强度试验、电镜扫描(SEM)试验和X射线衍射(XRD)试验探讨了厨余垃圾作为钙源的可行性。结果表明:再生钙源应用于MICP技术固化砂土具有可行性;经再生钙源生蚝壳固化后的沙土试样干密度、碳酸钙含量和无侧限抗压强度均比硝酸钙固化后的试样低,而渗透系数则相反;使用再生钙源固化砂土试样中的表观孔隙率较使用硝酸钙的固化砂土试样高;XRD和SEM试验的结果显示再生钙源获取的碳酸钙晶体形态以球霰石为主,硝酸钙获取的碳酸钙晶体则呈现方解石和球霰石的团簇状态;再生钙源替代化学钙源应用于MICP有助于提升该技术的环保可持续性。

In order to eliminate the adverse effects of chemical calcium sources in the microbial induced calcium carbonate precipitation(MICP) technology at the present stage, and to seek more ways to utilize the kitchen waste, this paper selected two kinds of recycled calcium sources of eggshell and scallop shell and used the calcium nitrate as a control. The feasibility of kitchen waste as calcium sources was investigated by permeation test, dry density test, unconfined compressive strength test,electron microscopy(SEM) test and X-ray diffraction(XRD) test. The results showed that the dry density, calcium carbonate content and unconfined compressive strength of the sand samples after curing by the recycled calcium sources were higher than those of the calcium nitrate cured samples, while the permeability coefficient is reversed. The apparent porosity of solidified sand using recycled calcium sources was higher than that of the solidified sand using calcium nitrate. Results of XRD and SEM test showed that the crystal form of calcium carbonate obtained from the recycled calcium sources was mainly calcite,and the calcium carbonate crystals obtained by calcium nitrate were calcite and vaterite which presented the clustered state.The strength of sand solidified by recycled calcium sources could meet the requirements of foundation treatment, and the utilization of recycled calcium source was more conducive to the application of MICP technology in more fields.