On the Modelling of Algal Biofouling Growth on Nano-TiO2 Coated and Uncoated Limestones and Sandstones

Abstract

Algal biofouling on archaeological and historic materials, as well as in modern building façade, is a common phenomenon that occurs when microorganisms of various nature adhere to the material, forming biological stains and patinas. It can significantly deteriorate the aesthetic and even mechanical quality of historic and archaeological artifacts. Thus, predicting the colonization progress of algae on treated and untreated materials can be helpful to establish appropriate schedules and methods of maintenance. In this way, the aim of this research was to modelize the algal colonization on nano-TiO 2 coated and uncoated stone surfaces, usually found in historic and archaeological artifacts, by following Avrami's theory. Particular attention was paid on correlating the model with some properties of the substrate, like roughness and porosity. Biofouling was tested on two sandstones and three limestone with different intrinsic characteristics (porosity, roughness) by means of an accelerated lab-scale test. A suspension of green alga Chlorella mirabilis and cyanobacteria Chroococcidiopsis fissurarum was used as biofouling. Digital image analysis was carried out in order to find the attachment rate and the growth of algal spots. Results show that the attachment specific rate increased linearly with time, and the assumption of a constant growth rate was acceptable. A good agreement between the simulation and the experimental results was obtained with a maximum error of 0.59%.

Effect of Inorganic Carbon Concentration on the Development of Subaerial Phototrophic Biofilms on Granite

“…These results may; therefore, involve negative impacts regarding the possible effects of an increase in atmospheric CO 2 on the stone colonization and biodeterioration processes. An increase in growth of cyanobacterial biofilms and in pigment concentrations may exacerbate the aesthetic impact of these biofilms on stone-made cultural heritage and; therefore, lead to treatments being necessary (e.g., biocide coating [42], laser cleaning [43] or application of natural oils [44]) and/or loss of value. An essential strategy to prevent colonization and subsequent biodeterioration is the selection of appropriate materials for building, ornamental purposes or replacement.…”

An empirical failure model to predict biofouling growth on fired bricks due to microalgae

“…As stated above, the starting point of this work is the modified Avrami's model [34,35] showed in (1):…”

“…Lastly, the parameter t1 represents the latency time [day] before a chromatic variation occurs on the material surface and the coefficient n is the Avrami's coefficient which can be assumed equal to 4 [34].…”

“…-when RH≥98% and 5°C≤T≤40°C growth can happen depending on T, P and R, otherwise it cannot [13,18]; -thus, P, R and T directly affect the microalgae coverage X through its parameters AC/AT, K and t1 [18,26,34,35].…”

Application of additional insulation to ETICS on surfaces with biocorrosion

“…One example is the article [11] that describes and analyses experiments regarding eutrophication and biodegradation of construction materials. This article also refers to article [12], which notes how rare studies of accumulation of microorganisms on construction materials are, due to the difficulty in predicting the behaviour of microorganisms and their relationship to construction materials and environmental conditions.…”