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This study aimed to evaluate the effects of variables on the process of lipases production by Aspergillus niger C by submerged fermentation (SmF). The production assays were performed in shake flasks for 72 hours at 150 rpm and 32°C. First, a fractional factorial design 2 5-1 (FFD) was carried out to evaluate the effect of the following process variables: sucrose, ammonium sulphate, soybean oil, yeast extract concentration and pH. After the selection of the variables that significantly influenced the lipase production, a central composite rotational design 2 2 (CCRD) was used, aiming to find the most favorable operational conditions. The selected assay condition (15.0 g.L-1 sucrose, 4.0 g.L-1 HIGHLIGHTS • Lipase was production by A. niger using sucrose and soybean oil as carbon source. • Experiment design was an efficient tool in improving A. niger lipase production. • Lipase production kinetics indicated good yield levels in a short fermentation time.

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Azo dyes, common in textile wastewater, have high photolytic and chemical stabilities, which make them difficult to be removed using conventional treatments. This study aims to evaluate a combined process using heterogeneous photocatalysis, with ZnO/UV or TiO 2 /UV (0.6 g catalyst L −1 solution/2-hr UV radiation), and a biological process for textile wastewater treatment. After the proposed treatments, the color and organic matter removals from synthetic wastewater (SW) and industrial wastewater (IW) were evaluated. For SW, the coupled photocatalytic (ZnO/UV or TiO 2 /UV)-biological system promoted a high extent of color removal (98%) and total organic carbon (TOC) reduction (>80%). Promising results were obtained with IW using combined photocatalytic (TiO 2 /UV)-biological treatments, reaching 97% and 63% of color and TOC removal, respectively. This process, coupling heterogeneous photocatalysis and a bioprocess, has proved to be a good alternative for the treatment of textile wastewater, not only for color removal but also for dye mineralization purposes. • Practitioner points• A combined process using heterogeneous photocatalysis (ZnO/UV or TiO 2 /UV) and biological process was evaluated for synthetic (SW) and industrial (IW) textile wastewaters treatment. • For SW, coupled process promoted high extent of colour and organic matter removals. • For IW, promising results were obtained with TiO 2 /UV-biological treatment (97% of colour and 63% of organic matter removals).

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This work aims evaluate the use of biocides in the microbiologically-influenced corrosion (MIC) of AISI 1020 carbon steel by sulfate-reducing bacteria (SRB) in artificial seawater. A natural biocide (garlic oil) and a commercial biocide (glutaraldehyde) were used to control the corrosion caused by these bacteria in artificial seawater. Microbial growth on the steel surface was evaluated by quantifying the sessile SRB using the most probable number (MPN) method. The action of biocides in the biocorrosion process was studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The biofilm formation and the corrosion products on the steel surface were observed by scanning electron microscopy (SEM). The results showed that, although it was not able to inhibit the growth of sessile SRB completely, garlic oil showed a greater reduction in the corrosion process when compared to glutaraldehyde, indicating its possible application as a natural biocide under these conditions.