Bacterial Induced Calcium Carbonate Precipitation (BICP) – Bio Cementation – Agriculture Assignment Help

Assignment Task:

i. Abstract:

Bio cementation is a novel technology that developed recently and new branch in engineering such as geotechnical and civil that addresses the implication of microbial activity for the improvement or stabilization of the soils. The most frequently consider a phenomenon is to attain it by microbial prompted calcite precipitation (MICP). This technique observed that the bacterial metabolic paths allow producing calcium carbonate precipitation (CaCO3) that would fix the particles of soils organized and consequently causing increase in soil strength and stiffness. The efficiency of this technology depends upon the microbial concentration, pH value, temperature and degree of saturation. The development of bio bricks is the most novel application of MICP because this discovery make bio cricks long term constructing material. Due to rapid urbanization the environment got effected by heavy metal special soil which pollutes our ground as well as water resources, for the removal of heavy metals from the soil this technique perform well. Despite of a lot of benefits of this valuable technique, many restrictions regarding our environment also observed such as the generation of by product i.e. ammonia and it would affect the environment badly.
There are various potentials for this unique and interesting outlet of geotechnology because it proposes a very sustainable way out for a restored future. Besides the present challenges, this technology has shown an unexploitedprospective for the betterment of the current day problems in soil enhancement.

1. Microbial Induced Calcium Carbonate Precipitation (MICP):

1.1. Introduction:
Ground improvement is a phenomena of improving soil or rocks. The stabilization of ground soil depends upon the strength, hydraulic conductivity, permeability, stiffness and compressibility. These all parameters are assisted by chemical or micro-organisms. For the consideration of new economic, green and sustainable techniques such as MICP has been considered. 

Microbial induced carbonate precipitation is a bio mineralization phenomenon that is done naturally producing calcium carbonate (CaCO3) inside the matrix of soil.
MICP is a biological technology which is driven by microorganisms and involves calcium carbonate (calcite or CaCO3) sleet, this phenomena is done by two mechanisms: first one is biologicallyprecisetool in which the organismsrule the growth and nuclean of the mineral constituents andcombines minerals independently in a quite different way and also maintain the environmental settings. Bacillus subtilis bacteria is the example of biologically controlled mechanism of MICP. However the other one is the biologically induced contrivance, in this fabrication of CaCO3 precipitates are somehow reliant on the environmental conditions.

To guarantee useful soilenhancement by MICP, the most crucial is the urease enzyme and ureolytic bacterial introduction and retention in the soil medium. The present bacteria could retain CaCO3 precipitation by the provision of a suitable solution. When Inappropriate bacteria retaining would occurred and it take to bacteria that are being removed or separated by an inoculation of the cementation solution subsequently, which further cause the uneven distribution of bacterial concentration and which result in  CaCO3 non-uniform distribution and strength decreases inside the bio cemented soil. The insertion of bacteria into soil could be done by two main methods:
(1) Injection method 
(2) Premixing method. 

The first method confirms removing the bacterial solution from highest to lowest and a retention time could be indicated for them so that it should be stick to the grains of sand before inoculation of the cementation solution. 

The premixing method involves the mixing of bacteria firstly with the soil mechanically before entering of the cemented solution.

1.2. Bacterial Induced Calcium Carbonate Precipitation (BICP):
Bacteria are omnipresent in all habitat of the earth, mounting in soil, present in glaciers, present in animal and plant bodies, organic matter, deep in the earth crust and radioactive waste water. More than a microbial habitat soil contain more genera and different forms of bacteria. These all includes really good nutrients and contains a lot of useful liquids in their pore spaces. 

Close to the ground surfaces, approximately 109 – 1012 microorganism are present inside the 1kg of soil mass.  In soil most of the bacteria that are more abundant are archea and eukarya

All microorganisms are considered worthy for bio mineralization phenomena due to their urease activity. They should be harmless to the environment while and after the improvement procedure.