The ability of microalgae to grow in nutrient-rich environments and to accumulate nutrients from wastewaters (WW) makes them attractive for the sustainable and low-cost treatment of WW. The valuable biomass produced can be further used for the generation of bioenergy, animal feed, fertilizers, and biopolymers, among others. In this study, Scenedesmus obliquus was able to remove nutrients from different wastewaters (poultry, swine and cattle breeding, brewery and dairy industries, and urban) with removal ranges of 95-100% for nitrogen, 63-99% for phosphorus and 48-70% for chemical oxygen demand. The biomass productivity using wastewaters was higher (except for poultry) than in synthetic medium (Bristol), the highest value being obtained in brewery wastewater (1025 mg/(L.day) of freeze-dried biomass). The produced biomass contained 31-53% of proteins, 12-36% of sugars and 8-23% of lipids, regardless of the type of wastewater. The potential of the produced Scenedesmus obliquus biomass for the generation of BioH through batch dark fermentation processes with Enterobacter aerogenes was evaluated. The obtained yields ranged, in mL H/g Volatile Solids (VS), from 50.1 for biomass from anaerobically digested cattle WW to 390 for swine WW, whereas the yield with biomass cultivated in Bristol medium was 57.6 mL H/g.

Scenedesmus obliquus (ACOI 204/07) microalgae were cultivated in cattle wastewater in vertical alveolar flat panel photobioreactors, operated in batch and continuous mode, after previous digestion in a hybrid anaerobic reactor. In batch operation, removal efficiencies ranges of 65 to 70% of COD, 98 to 99% of NH and 69 to 77.5% of PO after 12days were recorded. The corresponding figures for continuous flow were from 57 to 61% of COD, 94 to 96% of NH and 65 to 70% of PO with mean hidraulic retention time of 12days. Higher rates of CO fixation (327-547mgLd) and higher biomass volumetric productivity (213-358mgLd) were obtained in batch mode. This microalgae-mediated process can be considered promising for bioremediation and valorization of effluents produced by cattle breeding yielding a protein-rich microalgal biomass that could be eventually used as cattle feed.

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RESUMOEste trabalho apresenta os resultados de um estudo realizado durante 7 (sete) meses sobre a eficiência de sistemas alagados construídos, no tratamento de águas residuárias de laticínios, com ênfase na remoção de nitrogênio e fósforo. Os 6 (seis) sistemas experimentais foram construídos em tanques de PEAD com volume de 115 litros cada, com relação comprimento/largura na proporção de 2:1. Os materiais suporte utilizados foram brita 0 em três dos sistemas e brita 0 e areia em outros três, na proporção de 80% brita e 20% areia. Os sistemas foram operados em bateladas com ciclos de 48 horas, aplicando-se 7,5 litros do efluente por ciclo. Quatro das unidades experimentais foram cultivadas e duas mantidas como testemunhas. As espécies selecionadas foram as macrófitas Typha dominguensis e o Hedychium coronarium. A eficiência na remoção de compostos nitrogenados apresentou-se promissora com valores entre 29,4 a 73,4%, a remoção de fósforo pelos leitos foi inferior, atingindo eficiências entre 18,61 a 34,3%, valores promissores levando em conta a dificuldade da remoção destes elementos por sistemas convencionais.Palavras-chave: nutrientes eutrofizantes, ecotecnologia, efluentes de laticínios. Removal of nitrogen and phosphorus from dairy wastewater using constructed wetlands systems operating in batch ABSTRACTThis work presents the results of a study conducted for a period of seven months on the effectiveness of constructed wetland systems for the treatment of dairy wastewater aiming at removing, nitrogen and phosphorus. Six experimental systems were assembled with a net volume of 115 L using HDPE tanks, with length/width ratio of 2:1. In three of the systems, gravel 0 was used as substrate, while gravel 0 and sand was used in the three others, in the percentage of 80% and 20%, respectively. The systems were operated in batch cycles of 48 hours, applying 7.5 L of influent per cycle. Four of the experimental units were cultivated, and two kept as controls. The selected species chosen were the macrophytes, Typha domingensis and Hedychium coronarium. The removal efficiency concerning nitrogen compounds showed to be quite promising with values ranging from 29.4 to 73.4%, while phosphorus removal from the beds was lower, reaching efficiencies between 18.61 and 34.3%, considered good values, since the removal of these substances is quite difficult through conventional treatment.

This work assessed the effectiveness of using constructed wetlands (CW's) to treat dairy effluent. The purpose of the research was to evaluate the influence of substrates and cultivated plants on the efficiency of Biochemical Oxygen Demand (BOD) removal and pH regulation in six experimental units operating at pilot scale. Six CW's for dairy sewage treatment were constructed in 100-liter High-Density Polyethylene Ethylene (HDPE) tanks. Three Sistemas Alagados Construídos em Batelada: …

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