Performance of an anaerobic sequencing batch reactor operating under high organic loading in treatment of biodiesel wastewater.

Studies reporting the performance of anaerobic sequencing batch reactor (AnSBR) operating with high organic loadings are scarce. This study aimed to contribute to the technical and scientific literature by reporting the experience obtained when biodiesel wastewater was treated in an AnSBR applying organic loading rates (OLR) above those commonly used in batch reactor projects. For this, physicochemical and chromatographic analysis of the effluent were carried out. Further, the biomass was assessed chemically and morphologically, along with bacterial diversity characteristics. Supported by these analyses, the system performance was discussed in terms of COD remotion efficiency and buffering capacity. The AnSBR reached 10% of COD removal at the steady-state, which caused the biomass defragmentation and facilitated washout. This suggests that the startup and operation of AnSBR under optimized conditions with an average applied OLR of 11.3 gCOD L-1 d-1 worked as a pressure for the microbiota selection, stimulating the production of total volatile acids, which promoted system reduction efficiency and souring. In this context, food/microorganism ratios above 1.0 gCOD gTVS -1 d-1 can favor acidogenic activity, and total volatile acids/bicarbonate alkalinity concentration ratios above 1.9 may indicate acidification. The addition of support material for immobilizing/increasing biomass retention and/or operation under two-stage may be interesting alternatives for increasing AnSBR efficiencies under high OLRs.

Immunohistochemical, morphological and histometrical analyses of follicular development in Astyanax bimaculatus (Teleostei: Characidae) exposed to an organochlorine insecticide.

Thiodan® is an organochlorine insecticide used in agriculture that can reach aquatic ecosystems where it can affect fish reproduction. This research aimed to evaluate follicular development and the expression of integrin ß1, collagen type IV and caspase 3 by morphological, histometrical and immunohistochemical analyses of Astyanax bimaculatus exposed to Thiodan®. Treatments included three sublethal concentrations of Thiodan® (1.15, 2.30, and 5.60µgL-1) for 96h and a control without the insecticide. Mature females with ovaries in advanced follicular development were chosen for study (average weight: 11.52 ± 2.0g; average total length: 9.12 ± 0.64cm). The follicles of A. bimaculatus exhibited normal morphology, while the diameters of secondary follicles showed an increase (P< 0.05) in all concentrations when compared to the control group; a characteristic of follicles undergoing the initial stages of intoxication. Immunohistochemical analysis revealed secondary follicles with greater expression of integrin ß1 and collagen type IV in cytoplasm of follicular cells than in the primary follicles in all treatments and in the control. Immunolocalization of caspase 3 was detected in follicular cells during secondary development in all tested concentrations of Thiodan® and the control. These analyses demonstrate positive immunolocalization throughout the course of follicular development, even in fish exposed to varying concentrations of Thiodan® for 96h, demonstrating that follicular cells retain their physiological integrity.

Pathological and histometric analysis of the gills of female Hyphessobrycon eques (Teleostei:Characidae) exposed to different concentrations of the insecticide Dimilin(®).

Female individuals of Hyphessobrycon eques were exposed to Diflubenzuron (Dimilin(®)) in order to determine whether exposure to sublethal levels of this insecticide causes changes in gill morphology. Fish were exposed to 0.01, 0.1 and 1.0mgL(-1) for 96h and 17 days and then submitted to pathological and histometric evaluation. Pathological lesions, such as hyperplasia, lamellar fusion, vascular congestion, secondary lamellar disarray, vasodilatation, hemorrhage and increased lamellar epithelium, were significantly more common in the gills of fish exposed to Dimilin(®) than the control. Histometric analysis documented significant changes in blood vessel diameter, primary lamellae width and secondary lamellae length, and the appearance of hemorrhage foci in all concentrations tested. Even at low Dimilin(®) concentrations, the histopathological alteration index was mild to moderate, thereby indicating that the function of this tissue was compromised. These findings indicate that indiscriminate use of Dimilin(®) can adversely affect the structural integrity of the gills of H. eques, which can cause numerous problems for fish farming systems.

O inseticida Thiodan® sobre o desenvolvimento folicular de lambaris / Thiodan® insecticide on the follicular development of lambaris

O Thiodan(r) é um organoclorado a base de endosulfan que pode causar alterações morfológicas nos tecidos de peixes, dependendo da concentração e tempo de exposição. Este estudo teve como objetivo determinar a CL50-96h do Thiodan(r) (endosulfan 350g L-1) para fêmeas de lambaris Astyanax bimaculatus em período de reprodução e analisar a morfologia do desenvolvimento folicular em diferentes concentrações do agrotóxico. Foram feitos quatro experimentos: 1) sem aclimatação e sem alimentação; 2) sem aclimatação e alimentados; 3) com aclimatação de 10 dias e sem alimentação; 4) com aclimatação de 10 dias e alimentados. A CL50-96h determinada foi de 13,6µg L-1, com intervalo de confiança de 10,1 a 18,4µg L-1 (P<0,05). Em todos os experimentos, foram utilizadas três concentrações diferentes do Thiodan(r) inferiores à CL50-96h pré-determinada em laboratório de acordo com a NBR 15088 (ABNT, 2007). Os lambaris foram expostos ao Thiodan(r) por 96 horas em três concentrações subletais de 1,15; 2,3 e 5,6µg L-1 e um grupo controle, livre de agrotóxico. Morfologicamente, percebeu-se que a ação do Thiodan(r) nas concentrações subletais não alterou a morfologia do desenvolvimento folicular. Porém, o diâmetro folicular nos folículos secundários no experimento com aclimatação/com alimentação expostos ao Thiodan(r) foi maior em relação ao grupo controle (P<0,05). Esses dados sugerem que a reprodução pode ser afetada pelo produto químico e pode causar comprometimento no desenvolvimento folicular.

Thiodan(r) is an organochlorine based in endosulfan which can cause morphological changes in fish tissues exposed to it depending on the concentration and exposure time. This study aimed to determine the LC50-96h of Thiodan(r) (350g L-1 endosulfan) for lambaris females of Astyanax bimaculatus in a reproduction period and analyze the morphology of follicular development in different experiments. Four experiments were performed: without adaptation and no feeding, feeding without adaptation, with adaptation and without feeding, with adaptation and feeding. The LC50-96h determined was 13.6µg L-1, with a confidence interval from 10.1 to 18.4µg L-1 (P<0.05). The lambaris were exposed to Thiodan(r) for 96 hours in three sub-lethal concentrations of 1.15, 2.3 and 5.6µg L-1 and without pesticides control group. Morphologically, it was noted that the action of Thiodan(r) in sub-lethal concentrations did not alter the morphology of follicular development. However, the follicular diameter in secondary follicles in the experiment with adaptation and feeding exposed to Thiodan(r) was higher relative to the control group (P<0.05). These data suggest that reproduction may be affected by chemical and can cause impairment in the follicular development.

Avaliação de contaminação por mercúrio em Descoberto, MG / Evaluation of mercury contamination in Descoberto, MG

O mercúrio, elemento químico considerado não essencial a qualquer processo metabólico, é facilmente acumulado na maioria dos organismos. Ocorre naturalmente em formas orgânicas e inorgânicas, nos estados sólido, dissolvido e gasoso. Seu ciclo biogeoquímico envolve processos que ocorrem no solo, na água e na atmosfera. Em 2002, descobriu-se mercúrio elementar na zona rural do município de Descoberto, Minas Gerais, onde moram cerca de 70 famílias, e sua origem parece estar associada à exploração de ouro, que existiu na região no século 19. Neste trabalho, foram escolhidas três áreas para identificar possível contaminação da água, solo, sedimento e peixes por mercúrio, bem como para estabelecer valores de referência local e contraprova de resultados obtidos anteriormente. Verificaram-se elevadas concentrações no solo (0,26 a 0,55 mg.kg-1), sedimentos (0,13 a 0,61 mg.kg-1) e água (< 0,2 a 2,10 µg.L-1).

Mercury is a chemical element considered unessential to any metabolic process; however, it is easily accumulated in most organisms. It is naturally found in both organic and inorganic forms in solid, liquid and vapor states. Its biogeochemical cycle involves processes occurring in the soil, water and the atmosphere. In 2002, elementary mercury was found in the city of Descoberto, Minas Gerais, Brazil, where 70 families live, and its origin may be related to gold exploration that happened in this region in the 19th century. In this work, three areas were chosen to identify a possible mercury contamination of water, soil, sediment and fish samples and to establish local reference values and counter-evidence of the data previously obtained. Based on the results, high mercury concentrations in soil (0.26 to 0.55 mg.kg-1), sediments (0.13 to 0.61 mg.kg-1) and water (< 0.2 to 2,10 µg.L-1) were verified.