INTERACTION OF WASTEWATER MICROORGANISMS WITH GEOPOLYMERS AND CEMENTITIOUS MATERIALS

摘要

Traditional cement-based materials are formed via the hydration reactions of calcium silicate phases, whereas innovative and green geopolymers result from alkali activation of alumino-silicates to form a "room-temperature formed aluminosilicate glass". The interaction of microorganisms and geopolymer binders has not yet been explored. However, the potential biofilm formation can have a decisive influence on the material properties and its durability. This paper investigates the biofilm formation within different mortars, including geopolymers and standard cements exposed to microorganisms in a wastewater environment. The interactions of wastewater microorganisms with mortars were tested, as well as material alterations in an acidic environment. The samples were exposed for 35 days to wastewater flow under three types of field conditions, at different stages of cleaning the wastewater, therefore differing both on chemistry and biology. Formed biofilms were characterized using three approaches: protein concentration at the sample surface, bacterial respiration and Scanning Electron Microscopy (SEM). We found that geopolymers are significantly more resistant to acid treatments and presented less bacterial activity on their surface as compared to standard cements. The SEM analyses displayed the presence of biofilm on all samples exposed to organic-rich wastewater, but no biofilm on the samples exposed to wastewater effluent.