Browsing by Author "Guilherme, Henrique Castanheira"
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- Bioremediation of liquid effluents using synergy between Chlorella vulgaris and bacteriaPublication . Guilherme, Henrique Castanheira; Simões, Rogério Manuel dos SantosNowadays, excessive population growth, overexploitation of resources and increased industrial activity has put a huge stress on several ecosystems, with problems such as occupation of arable land and pollution of watercourses endangering human populations and habitats. One of the answers for this is the use of microalgae as it is known that they have huge potential as food and organic compounds source while occupying non-arable land as well as a largely untapped bioremediation potential. However, despite all this potential its cultivation is still largely not cost effective, as such, several methods to augment its potential are suggested. One of these is by using effluents as substrate, as several of them are rich in macronutrients. Still, one underexploited method is the use of synergy between microalgae and bacteria to increase culture growth. To this end, the microalgae Chlorella vulgaris and three different effluents were used, each with different origins and therefore different physicochemical characteristics in a series of essays. The process was evaluated by analysing parameters such as microalgae growth, COD value and macronutrient assimilation in order to depict the cultures potential as a bioremediation and microalgae growth enhancing assets. The results obtained showed that in the effluents studied, microalgae cultures were able to achieve moderate to strong growth notwithstanding problems such as high organic compounds such as phenols or high macronutrients concentration that characterize the effluents OMWW and LWW respectively. The bioremediation results depend on the parameter analysed, as microalgae showed extremely high nutrients assimilation capability while it is not the case for COD. Within these positive results differences were observed between axenic and xenic cultures, as the presence of bacteria generally served as an enhancer of growth. This was especially the case in cultures where a bacterial population indigenous to the effluent was used as it was the case with MWW. Nonetheless, as far as COD bioremediation regards, the presence of these mixed cultures while did not revealed significant divergences from pure microalgae cultures. Thus, it can be said that the use of mixed bacteria-microalgae culture in effluents is a very effective tool to enhance culture growth while simultaneously decreasing associated costs of this kind of industry and possessing good bioremediation capabilities.