Nitrogen and phosphorus present in sewage can be used for microalgae growth, possibiliting cost reduction in the production of microalgae at the same time that it decreases the eutrophication potential of the effluent. This research aimed at monitoring the native community of microalgae and coliform bacteria in a secondary effluent from anaerobic municipal sewage treatment. Two treatments (aerated and non-aerated) were performed to grow microalgae under semi-controlled conditions in semi-closed photobioreactors in a greenhouse. The results showed no significant pH and coliforms (total and Escherichia coli) variation between treatments. Nutrient concentrations were reduced supporting microalgae growth up to 107 cells.mL−1independent of aeration. Exponential growth was obtained from the first day for the non-aerated, but a 5 day lag phase of growth was obtained for the aerated. Chlorella vulgaris was the dominant microalgae (99.9%) in both treatments. In the aerated, 5 algae classes were detected (Chlorophyceae, Cyanophyceae, Chrysophyceae, Bacillariophyceae and Euglenophyceae), with 12 taxa, whereas in the non-aerated, 2 classes were identified (Chlorophyceae and Cyanophyceae), with 5 taxa. We concluded that effluent is viable for microalgae growth, especially Chlorella vulgaris, at the same time that the eutrophication potential and coliforms are decreased, contributing for better quality of the final effluent.

A necessidade de algas limpas e custo de produção baixo demanda as investigações sobre a resposta fisiologica das algas sob condições diferentes de crescimento. Nesta pesquisa, investigamos o crescimento, produção biomassa e composição bioquímica de Chlorella vulgaris cultivada em três meios de crescimento (LC Oligo, Chu 10 e WC). A maior densidade celular foi obtida em LC Oligo, enquanto mais baixo em meio Chu 10. Concentrações e rendimentos de clorofila a, carboidratos e proteínas foram mais altas em meios de Chu e Oligo. Análise de classe lipidicas mostrou que as concentrações e rendimentos dos hidrocarbonetos (HC), ésteres de esterol (SE), ácidos graxos livres (FFA), álcoois alifáticos (ALC), lipídios polares móveis em acetona (AMPL) e fosfolipídios (PL) foram maiores no meio Chu. Triglicerídeos (TAG) e esterol livre (ST) foram maiores no meio LC Oligo. Os resultados sugerem que pra o cultivo rentável, LC Oligo é a melhor escolha entres os meios estudados, como ele salvou o custo de comprar as vitaminas e EDTA associados com os outros meios, enquanto, ao mesmo tempo resultou no melhor desempenho de crescimento e produção biomassa.

The need for clean and low-cost algae production demands for investigations on algal physiological response under different growth conditions. In this research, we investigated the growth, biomass production and biochemical composition of Chlorella vulgaris using semi-continuous cultures employing three growth media (LC Oligo, Chu 10 and WC media). The highest cell density was obtained in LC Oligo, while the lowest in Chu medium. Chlorophyll a, carbohydrate and protein concentrations and yield were highest in Chu and LC Oligo media. Lipid class analysis showed that hydrocarbons (HC), sterol esthers (SE), free fatty acids (FFA), aliphatic alcohols (ALC), acetone mobile polar lipids (AMPL) and phospholipids (PL) concentrations and yields were highest in the Chu medium. Triglyceride (TAG) and sterol (ST) concentrations were highest in the LC Oligo medium. The results suggested that for cost effective cultivation, LC Oligo medium is the best choice among those studied, as it saved the cost of buying vitamins and EDTA associated with the other growth media, while at the same time resulted in the best growth performance and biomass production.

A fluorescência de substâncias húmicas de origem terrestre foi investigada através da técnica de fluorescência sincronizada, e as amostras mostraram duas bandas principais (lex/lem 380/398, 440/458 nm) quando analisadas sem adição do metal paramagnético cobre. Uma terceira banda (lex/lem 502/520 nm) foi detectada após severa extinção de fluorescência da segunda banda causada pela adição de cobre. Uma outra banda, mais energética (lex/lem 333/351 nm) foi detectada em amostras marinhas, porém ausente do material de origem terrestre. Os efeitos de cobre sobre a intensidade e forma do espectro de fluorescência sincronizado e a utilização desta técnica como marcadores são discutidas.

Two fluorescence bands were detected using synchronous-scan fluorescence on samples of terrestrially derived humic substances (lex/lem 380/398, 440/458 nm) without the addition of copper. A third band (lex/lem 502/520 nm) was detected after severe quenching of the second band (lex/lem 440/458 nm) caused by additions of copper. A more energetic band (lex/lem 333/351 nm) is present in marine DOM, but absent in the terrestrial material. The effects of copper on both the intensity and shape of the synchronous-scan fluorescence spectra and this technique’s potential use as a tracer are discussed.