Microbially included calcite coating layer on concrete surface as inhabitance of coral to produce artificial coral reef

The artificial reefs have positive environmental impact due to increase of aquatic biodiversity in coastal areas and enhanced consumption of CO₂ by photosynthetic epibiota. The aim of this study is to establish a new biocalcification method to enhance the creation of coral reefs and other ecosystems of marine epibiota. This paper presents a novel approach for the formation of calcite coating layer on concrete block surface by microbially induced carbonate precipitation (MICP) using urease active bioslurry. The bioslurry is pre-formed urease active crystals consisting of CaCO₃ and imbedded urease active bacterial cells. By coating the bioslurry on the surface of concrete blocks followed by submerging in a cementation solution, a mixture of CaCl₂, MgCl₂ and urea, the loose bioslurry turned into a dense and strong calcite deposit layer. By alternating the usage of the bioslurry and cementation solution, calcite layers with various thickness were established and their bio-compatibilities were also evaluated by monitoring biofilm growth on the calcite surface. This MICP based calcite coating approach has potential to be used in marine environment to facilitate colonization of marine microorganisms, such as corals.