Oil sludge or waste generated in transport, storage or refining forms highly stable mixtures due to the presence and additives with surfactant properties and water forming complex emulsions. Thus, demulsification is necessary to separate this residual oil from the aqueous phase for oil processing and water treatment/disposal. Most used chemical demulsifiers, although effective, are environmental contaminants and do not meet the desired levels of biodegradation. We investigated the application of microbial biosurfactants as potential natural demulsifiers of petroleum derivatives in water emulsions. Biosurfactants crude extracts, produced by yeasts (Candida guilliermondii, Candida lipolytica and Candida sphaerica) and bacteria (Pseudomonas aeruginosa, Pseudomonas cepacia and Bacillus sp.) grown in industrial residues, were tested for demulsification capacity in their crude and pure forms. The best results obtained were for bacterial biosurfactants, which were able to recover about 65% of the seawater emulsified with motor oil compared to 35–40% only for yeasts products. Biosurfactants were also tested with oil-in-water (O/W) and water-in-oil (W/O) kerosene model emulsions. No relationship between interfacial tension, cell hydrophobicity and demulsification ratios was observed with all the biosurfactants tested. Microscopic illustrations of the emulsions in the presence of the biosurfactants showed the aspects of the emulsion and demulsification process. The results obtained demonstrate the potential of these agents as demulsifiers in marine environments.

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Anthropogenic and natural actions cause internal and external fractures in concrete. To recover these structures, bio-concretes have been developed with bacteria of the genus Bacillus. These microorganisms consume calcium lactate, synthesize calcium carbonate and biomineralize CaCO3 crystals within the structures of concrete. The aim of the present study was to construct equipment, denominated “Cascade System for Biomineralization in Cement” (CSBC), to determine the limiting velocity of the biomineralization of CaCO3. The construction of the equipment took into consideration chemical and biochemical phenomena responsible for biomineralization. Parts made with 3D printing and a circuit with Arduino UNO R3 board were used in the assembly of the system. The prototype proved to be stable and can be considered a promising tool for future application in research of the regeneration of reinforced concreted in a practical, fast and economical way, especially to the energy sector.