Explore the vast range of titles available.

The irregular damp dark staining on the stonework of a salt-contaminated twelfth century granite-built chapel is thought to be related to a non-homogeneous distribution of salts and microbial communities. To enhance understanding of the role of microorganisms in the presence of salt and damp stains, we determined the salt content and identified the microbial ecosystem in several paving slabs and inner wall slabs (untreated and previously bio-desalinated) and in the exterior surrounding soil. Soluble salt analysis and culture-dependent approaches combined with archaeal and bacterial 16S rRNA and fungal ITS fragment as well as with the functional genes nirK , dsr , and soxB long-amplicon MinION-based sequencing were performed. State-of-the-art technology was used for microbial identification, providing information about the microbial diversity and phylogenetic groups present and enabling us to gain some insight into the biological cycles occurring in the community key genes involved in the different geomicrobiological cycles. A well-defined relationship between microbial data and soluble salts was identified, suggesting that poorly soluble salts (CaSO 4 ) could fill the pores in the stone and lead to condensation and dissolution of highly soluble salts (Ca(NO 3 ) 2 and Mg(NO 3 ) 2 ) in the thin layer of water formed on the stonework. By contrast, no direct relationship between the damp staining and the salt content or related microbiota was established. Further analysis regarding organic matter and recalcitrant elements in the stonework should be carried out. Key points • Poorly (CaSO 4 ) and highly (Ca(NO 3 ) 2 , Mg(NO 3 ) 2 ) soluble salts were detected • Halophilic and mineral weathering microorganisms reveal ecological impacts of salts • Microbial communities involved in nitrate and sulfate cycles were detected

The global water shortage alert has been upgraded to a higher risk level. Consequently, a sustainable approach for ecofriendly, energy efficient water desalination is required for agricultural and municipal water reuse. In this study, an energy-efficient biological desalination process was used to treat chloride anions, which are the most abundant anion salt in seawater. Three algal species were studied: Scenedismus arcuatusa (S. arcuatusa), Chlorella vulgaris (C. vulgaris), and Spirulina maxima (Sp. maxima), under different operating conditions (saline concentrations, contact time, high light intensity, and CO2 supply), and two kinetic models were used. It was identified that under a high light intensity and CO2 supply, S. arcuatusa enhanced chloride removal from 32.42 to 48.93%; the daily bioaccumulation capacity (Qe), according to the kinetic models, was enhanced from 124 to 210 mg/g/day; and the net biomass production was enhanced from 0.02 to 0.740 g/L. The EDX analysis proved that salt bioaccumulation may be attributed to the replacement of Ca2+ and Mg2+ with Na+ and K+ through algal cells. The study’s findings provide promising data that can be used in the search for novel energy-efficient alternative ecofriendly desalination technologies based on algae biological systems with biomass byproducts that can be reused in a variety of ways.

High levels of nitrate contamination of granite stone are a major problem, affecting large surfaces of many historical monuments, particularly in the north-west of Spain. This study showed a comparison between different traditional and biotechnological desalination methods in order to evaluate the most appropriate cleaning treatment for nitrate desalination of granite. Three types of traditional desalination methods (with cellulose and/or sepiolite) were compared with two types of bacterial denitrifying treatments that used Pseudomonas stutzeri (with cotton wool or with agar 2% as delivery systems). The in-situ tests were carried in the Cristo Chapel of Stª Mª de Conxo in Santiago de Compostela (Spain), which has a high nitrate salt content in its granite pavement. Conductivity and nitrate content measurements, biological monitoring and digital image analysis were performed to determinate the efficacy of each method. The findings showed that both techniques succeeded in reducing salt content, but bio-desalination was the more effective method tested. This work contributes to the practical implementation of BTCH (Biocleaning Technologies for Cultural Heritage) for the bio-desalination of granite surfaces, and to the evaluation of the use of non-destructive cleaning techniques based on digital imaging.

Biocleaning technology is based on the use of safe environmental microorganisms for green cultural heritage (CH) restoration. Compared with traditional cleaning products, this biological technique is very specific, effective, and nontoxic. This innovative biotechnological application has been used for recovering diverse monuments and artworks. Most CH in situ surfaces that are treated with microorganisms are small areas; however, some important pathologies, such as salt contamination, can affect high dimension artistic surfaces. The purpose of this study is to analyze and overcome the problems and limitations of scaling up the bio-desalination protocol for in situ applications. Three water-based gel delivery systems and three heating systems were tested in situ and evaluated in terms of performance difficulty, efficacy, and costs. The tests were carried out on the salt contaminated granite pavement of Cristo Chapel of Sta Ma de Conxo in Santiago de Compostela (Spain). Ground agar 2% and a heating electric mat were selected as the best performing systems. The implemented protocol was applied for the bio-desalination of the 233 m2 Chapel pavement. Conductivity, nitrate–nitrite measurements, biological monitoring, and digital image analysis were performed to determine the efficacy of the treatment. This research allowed for the development of an innovative and optimized in situ, high dimension bio-desalination application protocol transferable to other large scale, in situ biocleaning strategies.

Many technologies can be used to solve the clean water crisis. One of the technologies is desalination, but this technology is expensive. So that, it is necessary to find cheaper desalination technology and easier to operate. Bio-desalination is a technology that utilizes bacteria to remove sodium and chloride ions in seawater. In this research, the application of the phytotechnology concept for bio-desalination reactors was carried out. Bio-desalination technology used the uniqueness of mangrove plants ( Avicennia marina ) in a reed bed system reactor that adapted from a reed bed system commonly used in constructed wetlands (CWs). The aim of the research was to determine the uptake of sodium and chloride ions by Avicennia marina in a reed bed system bio-desalination reactor. The namely of reactor were AM15‰, AM25‰, AMVA15‰ and AMVA25‰. The VA code was shown that Vibrio alginolyticus addition in this reactor. The artificial saline water with initial salinity of 15‰ and 25‰ was chosen based on our previous study. Parameter of salinity was determined using salinometer. Concentration of sodium and chloride ions were analyses using ion chromatography. Based on the results, the concentration of sodium and chloride ions in Avicennia marina at AM15‰ were 843.18 mg/kg and 4959.96 mg/kg, respectively. Meanwhile, those were 1410.01 mg/kg and 5292.64 mg/kg at AM25 ‰, respectively. The concentration of sodium and chloride ions in AMVA15‰ were 1003.39 mg/kg and 3186.96 mg/kg, and it were 8036.43 mg/kg and 9783.91 mg/kg at AMVA25‰. The value of Bio-concentration Factor (BCF) and Translocation Factor (TF) were greater than 1, it indicated that Avicennia marina was as an hyperaccumulator plant for sodium and chloride ions. In conclusion, the Avicennia marina can be used in reed bed system bio-desalination reactor to reduce salinity.