M. Pachés

Wastewater nutrient removal in a mixed microalgae–bacteria culture: effect of light and temperature on the microalgae–bacteria competition

ABSTRACT The aim of this study was to evaluate the effect of light intensity and temperature on nutrient removal and biomass productivity in a microalgae–bacteria culture and their effects on the microalgae–bacteria competition. Three experiments were carried out at constant temperature and various light intensities: 40, 85 and 125 µE m−2 s−1. Other two experiments were carried out at variable temperatures: 23 ± 2°C and 28 ± 2°C at light intensity of 85 and 125 µE m−2 s−1, respectively. The photobioreactor was fed by the effluent from an anaerobic membrane bioreactor. High nitrogen and phosphorus removal efficiencies (about 99%) were achieved under the following operating conditions: 85–125 µE m−2 s−1 and 22 ± 1°C. In the microalgae–bacteria culture studied, increasing light intensity favoured microalgae growth and limited the nitrification process. However, a non-graduated temperature increase (up to 32°C) under the light intensities studied caused the proliferation of nitrifying bacteria and the nitrite and nitrate accumulation. Hence, light intensity and temperature are key parameters in the control of the microalgae–bacteria competition. Biomass productivity significantly increased with light intensity, reaching 50.5 ± 9.6, 80.3 ± 6.5 and 94.3 ± 7.9 mgVSS L−1 d−1 for a light intensity of 40, 85 and 125 µE m−2 s−1, respectively.

Selecting the most suitable microalgae species to treat the effluent from an anaerobic membrane bioreactor

ABSTRACT Conventional treatments for nutrient removal in wastewater are shifting to Anaerobic Membrane Bioreactors, which produce a high-quality effluent with minimum sludge production. The effluent resulting contains high nitrogen and phosphorus load that can be eliminated by microalgae culture. The aim of this study is to evaluate the ammonium and phosphorus removal rate of different microalgae species in the effluent of an anaerobic treatment. For that, 4 different microalgae species have been tested (Chlamydomonas reinhardtii, Scenedesmus obliquus, Chlorella vulgaris and Monoraphidium braunii) in batch monoculture and mixed conditions. Results indicate that all species are able to eliminate both P and N in the medium with high removal rates. However, a slight interspecies competition may boost these removal rates and productivity values ensuring, the success of the process. GRAPHICAL ABSTRACT

INFORMATION LITERACY APPLIED TO ENGINEERING

The Information literacy is defined as the competence, aptitude and knowledge to access, to use, to administrate and to communicate properly the information within the aim of study, research or even for the professional exercise. In our current information society to get and to understand correctly the information and to deal with it is a guarantee for successful outcomes. That is the reason why University, as an education institution must guarantee the acquisition of the whole set of competences that allow students to search, assess and analyze the information needed related to any knowledge area. It is important to highlight that this becomes essential in a digital world as the one we have. For that, communication and information technology (C&IT) become necessary to allow students to access to a wide range of information resource. It is not only a matter of finding out the information, but to analyze and apply the information to generate new knowledge. Engineering schools must develop clear strategies to address the acquisition and application of this competence using these technologies. This research is focused on the application process to acquire the information literacy competence for civil engineering students related to environmental impact. For that purpose, different stage in the information literacy process has been defined and deeply analyze. The most difficulties founded by students are discussed and some methodologies to enhance the process are proposed.