Abstract The textile industry demonstrates a polluting potential from the planting of cotton to the release of wastewater. The presence of dyes in water bodies decreases the passage of sun rays and directly affects the photosynthetic organisms and the ecosystem. Fungi have potential in the treatment of wastewater containing dyes with complex organic structures due to enzymes that they produce. This study evaluated the use of Phanerochaete chrisosporium in the treatment of synthetic effluent from textile industry containing indigo carmine (20 mg/L). The fungus was immobilized in a semibatch reactor. Glucose was the cosubstrate employed in the experiment and it was used in the system at 1g/L at the beginning of the process and 0.5 g /L after 24 hours of reaction. Average dye removal was 84±10% and chemical oxygen demand removal was 79±14%. For nitrogen compounds, the removal efficiencies were 87±11%, 81±11% and 91±9% for ammonia, nitrite and nitrate, respectively. The pH of the medium remained in the acidic range (2.57 to 5.00) throughout the process, with the lowest values recorded in the effluent of each cycle, justified by the release of organic acids from fungi metabolism. There was contamination of the medium by bacteria (710,000 CFU/mL), but the colonies count showed a predominance of fungi (1,365,000 CFU/mL). With the use of the semibatch system after reading of glucose it was observed that the efficiency of dye removal evolved from 72±17% to 84±10%, producing a final effluent with 3.35±1.99 mg/L of indigo, which proves that treatment configuration analyzed is satisfactory for dye removal.

RESUMO A agroindústria gera grandes volumes de resíduos com carga poluidora elevada, o que exige o desenvolvimento de tecnologias para minimização de impactos causados pela disposição inadequada desses resíduos no ambiente. A produção de ácido cítrico utilizando resíduos agroalimentares como substrato para fermentação é uma solução para a redução da carga orgânica desses poluentes, além de agregar valor econômico pela geração de produto rentável. Aspergillus niger AN 400 foi utilizado para produzir ácido cítrico a partir de soro de queijo. A pesquisa foi dividida em três fases, conforme adição de açúcar extra (50, 100 e 150 g.L-1): Fase I, com glicose; Fase II, com sacarose; e Fase III, apenas com o soro de queijo, sem adição extra de açúcar. Os reatores permaneceram sob agitação de 150 rpm e a 30ºC, por 10 dias. A maior concentração de ácido cítrico (2.379 mg.L-1) foi observada quando da adição de 100 g.L-1 de glicose. Porém, em termos de produtividade, os maiores valores foram registrados nos reatores com 50 (458 mg.L-1.dia-1) e 100 g.L-1 (745 mg.L-1.dia-1) de sacarose, seguido pelo reator que continha apenas soro de queijo, sem adição de açúcar extra (313 mg.L-1.dia-1), demonstrando o potencial desse resíduo para a obtenção desse ácido de grande interesse comercial.

ABSTRACT The agro-industry generates large volumes of waste with high organic load, which requires the development of technologies to minimize the impacts caused by the improper disposal of this waste on the environment. The citric acid produced by agro food wastes as substrate for fermentation is a solution to reduce the organic load of these pollutants and add economic value by generating a profitable product. Aspergillus niger AN 400 was used to produce citric acid from cheese whey. The study was divided in three phases according to the addition of extra sugar (50, 100, 150 g.L-1): Phase I, with glucose; Phase II, with sucrose, and Phase III, with cheese whey only, without adding extra sugar. The reactors remained under agitation 150 rpm and at 30ºC for 10 days. The highest concentration of citric acid (2,379 mg.L-1) was observed upon the addition of 100 g.L-1 of glucose. However, the greatest yields were recorded in the reactors with 50 (458 mg.L-1.day-1) and 100 g.L-1 (745 mg.L-1. day-1) of sucrose, followed by the reactor that contained only cheese whey, without adding extra sugar (313 mg.L-1.day-1), demonstrating the potential of this waste to obtain citric acid with a great commercial interest.

ABSTRACT The mineralization of the azo dye congo red by the fungi Phanerochaete chrysosporium was studied in two sequential batch bioreactors (R1 and R2), operated in cycles of 48 h (step I) and 24 h (step II). In step I, glucose concentration was 1 g.L-1 in both reactors and in step II, 1 g.L-1 of glucose was maintained in R1, but R2 received no addition of glucose. In step I, the average dye removal efficiencies were 76 ± 29 % (R1) and 53 ± 15% (R2), while in step II the averages recorded for dye removal for R1 and R2 were 84 ± 15 and 70 ± 28%, respectively. The rates of dye removal were 0.04 h-1 in R1 and 0.03 h-1 in R2 in step I. Higher rates were obtained in step II, 0,07 h-1 and 0,02 h-1 for R1 and R2, respectively. The highest dye removal occurred in R1 and, in R2, the residual dye was further removed. Laccase was the oxidised at higher amount, in step I was 54 μmol.min-1 for R1 and 38 μmolmin-1 for R2. The proposed treatment system was very effective in removing the azo dye, however the mineralization may not be complete and some by-products may have been formed, according to spectrofotometric analysis, were the peak corresponding to benzene, 220 nm, persisted.

RESUMO Foi estudada a remoção de compostos BTEX (benzeno, tolueno, etilbenzeno e xilenos) em reator de escoamento contínuo e mistura perfeita, com inóculo de Aspergillus niger AN 400, operado sob o tempo de detenção hidráulica (TDH) de 12 horas para avaliar a eficiência do sistema na biorremediação de água poluída com gasolina na presença (Etapa I) e na ausência (Etapa II) de glicose (0,5 g.L-1). A água poluída com gasolina foi preparada na proporção de 10:1000 mL (gasolina:água). Na primeira etapa foi ainda estudada a influência da adição de nutrientes no afluente sobre a eficiência do processo. A adição de nutrientes foi benéfica ao processo e, mesmo com a retirada da glicose, a eficiência foi mantida, devido à metabolização do etanol - presente na gasolina brasileira em 25% - pelos fungos, sendo ambos fontes de carbono de assimilação mais fácil para obtenção de energia; o etanol e a glicose, foram usados como cossubstratos na degradação dos BTEX. Assim, na Etapa 2, quando somente havia o etanol no meio, chegou-se a percentuais médios de 88% para benzeno, 90% para tolueno, 90% para etilbenzeno, e de 91% para meta, para e orto-xileno (m, p e o-xileno), com formação de subprodutos fenólicos. A população fúngica predominou no meio ao longo de toda a operação do reator.

ABSTRACT The removal of benzene, toluene, ethylbenzene and xylene (BTEX) compounds by Aspergillus niger AN 400 was studied in a continuous flow reactor which was operated at hydraulic retention time (HRT) of 12 hours evaluate the efficiency of the system in the bioremediation of water polluted with gasoline in the presence (Step 1) and absence (Step 2) of 0.5 g.L-1 glucose. In the first step it was also studied the influence of the addition of nutrients in the influent on the efficiency of the process. The addition of nutrients was beneficial to the process and, with the removal of glucose, the efficiency was maintained due to the use of ethanol - which is a Brazilian gasoline constituent (25%) - and was used as co-substrate. Both ethanol and glucose are more easily assimilated carbon and energy sources for fungi and were used as co-substrate in the degradation of BTEX. Thus, in Step 2, when only ethanol was in the biomedia, averages percentage of 88% for benzene, 90% in toluene, 90% ethylbenzene and 91% for meta, para and ortho-xylene (m, p and o-xylene) were reached, with the formation of phenolic by-products in between. The fungal population in the middle prevailed throughout the operation of the reactor.

RESUMO Água residuária têxtil foi tratada com Aspergillus niger AN 400 em reator de bateladas sequenciais, em ciclos de 48 h para avaliar o efeito de fonte adicional de nitrogênio sobre a eficiência do sistema alimentado com efluente diluído (10% v/v) e glicose (3 g.L-1). O afluente recebeu fonte adicional de nitrogênio (etapa I), acarretando em excesso de nitrogênio amoniacal (192 mg.L-1) no meio, resultando em remoção de matéria orgânica de 85%, porém em apenas 55% de remoção de corante. Ao se diminuir a concentração média de amônia para 98 mg.L-1 (etapa II), a remoção de corante (83%) passou a ser superior à de matéria orgânica, de 69%, mostrando o efeito negativo de concentrações elevadas de amônia sobre o sistema, favorecendo ainda o crescimento de bactérias, o que provavelmente inibiu a produção de enzimas fúngicas e contribuiu para a perda de eficiência na remoção de corante e formação de subprodutos.

ABSTRACT Textile wastewater was treated by Aspergillus niger AN 400 in sequential batch reactor, which was operated in cycles of 48 h in order to evaluate the effect of an additional source of nitrogen on the system's efficiency, which was fed with effluent diluted (10% v/v) and glucose (3 g.L-1). The influent received addition of an external source of nitrogen (phase I), in which there was excess ammonia (192 mg.L-1) in the medium, resulting in organic matter removal of 85%, but in only 55% removal of dye. In the phase II, when the average concentration of ammonia in the medium was lower (98 mg.L-1), removal of dye (83%) became higher than that of organic matter (69%), showing the negative effect of high concentrations of ammonia over the system and favoring the growth of bacteria, which probably inhibit the production of fungal enzymes and contributed to the loss of efficiency in the removal of dye and the formation of byproducts.

This work sought to evaluate the ability of fungi Phanerochaete chryosporium to degrade congo red azo dye in batch reactor, evaluate the influence of glucose and wheat bran as co-substrates on the removal of the dye in the medium and investigate the influence of ammonium chloride, ammonium nitrate and ammonium sulfate as the inorganic nitrogen source for the process. Wheat bran was not effective satisfactorily for the removal of dye and organic matter had no desired effect for the removal of color and organic matter and showed the lowest values of k2, 0.008 M-1.d-1and 0.0004 M-1.d-1, respectively. Glucose presented the best response with the highest final percentage of dye removal (97%) and rate of dye removal (0.017 M-1.d-1), without adding an external source of nitrogen.

Um reator em batelada, aerado, com biomassa imobilizada de Aspergillus niger AN400 foi operado durante 10 ciclos de 7 dias para remover benzeno (200 mg.L-1), tolueno (200 mg.L-1) e xileno (50 mg.L-1) - BTX - e de nutrientes de meio basal. O reator era alimentado semanalmente com 4 L do meio e glicose - 1 g.L-1, na Fase I, e 0,5 g.L-1, na Fase II. Os BTX foram detectados até o quarto dia de operação, em todos os ciclos. As melhores eficiências médias de remoção foram na Fase I: 75%de matéria orgânica solúvel, 80% de ortofosfato e 77% de amônia. O reator pode ser uma alternativa viável para tratamento de águas poluídas com BTX, porém há a necessidade de estudar o comportamento do reator durante período de operação mais longo e com ciclos reacionais mais curtos, bem como da identificação dos metabólitos produzidos.

A batch reactor with air and immobilized biomass of Aspergillus niger AN400 was operated during 10 cycles of 7 days to remove benzene (200 mg.L-1), toluene (200 mg.L-1), and xylene (50 mg.L-1) - BTX - and nutrients from basal medium. The reactor was weekly fed with 4 L of the medium and glucose - 1 g.L-1 (Phase I) and 0.5 g.L-1 (Phase II). The BTX had been detected until the fourth day of operation in all cycles. The best efficiencies of removal had been in Phase I: 75% of soluble organic matter, 80% of orthophosphate and 77% of ammonia. The reactor can be a viable alternative for the contaminated water treatment with BTX. However it has the necessity to study behavior of the reactor during longer period of operation and with shorter reaction cycles, as well as the identification of the produced metabolites.

A sequential batch reactor (4 L) inoculated with Aspergillus niger was operated in order to remove congo red dye (10 mg L-1). The feeding of the reactor was done to each 7 days. The glucose was added in the concentration of 1 g.L-1 (Stage I) and 0.5 g L-1 (Stage II). The Stage III occurred without glucose addition. The Stage I was great to process, because the system reached the greater dye removal (95%) as well as the kinetic parameters ware the best - K M (0.7 g L-1) and k1 (0.025 h-1).