Abstract Gold mining and ore processing are activities of great economic importance. However, they are related to generation of extremely polluted effluents containing high concentrations of heavy metals and low pH. This study aims to evaluate the optimal conditions for gold mining effluent treatment by crossflow membrane filtration regarding the following variables: nanofiltration (NF) and reverse osmosis (RO) membrane types, feed pH and permeate recovery rate. It was observed that retention efficiencies of NF90 were similar to those of RO membranes though permeate fluxes obtained were 7-fold higher. The optimum pH value was found to be 5.0, which resulted in higher permeate flux and lower fouling formation. At a recovery rate above 40% there was a significant decrease in permeate quality, so this was chosen as the maximum recovery rate for the proposed system. We conclude that NF is a suitable treatment for gold mining effluent at an estimated cost of US$ 0.83/m3.

Abstract This study evaluated the technical and economic feasibility of membrane bioreactors (MBR) followed by nanofiltration (NF) for dairy wastewater treatment in order to reuse the treated effluent. It was observed that the MBR efficiently removed the organic matter and color of the feed effluent; however, due to the high concentration of dissolved solids in the permeate, it was necessary to use nanofiltration as a polishing step. The final treated effluent could be reused in the industry for cooling, steam generation and cleaning of external areas. A preliminary economic analysis showed the feasibility of the proposed system. The internal rate of return was greater than or equal to 32% when membrane lifespan was at least 2 years and the depreciation time was 15 years. The total cost of the proposed treatment system ranged from R$ 9.99/m3 to R$ 6.82/m3, depending on membrane lifespan.

Among the food industries, the dairy industry is considered to be the most polluting one because of the large volume of wastewater generated and its high organic load. In this study, an aerobic membrane bioreactor (MBR) was used for the treatment of wastewater from a large dairy industry and two hydraulic retention times (HRT), 6 and 8 hours, were evaluated. For both HRTs removal efficiencies of organic matter of 99% were obtained. Despite high permeate flux (27.5 L/h.m²), the system operated fairly stablely. The molecular weight distribution of feed, permeate and mixed liquor showed that only the low molecular weight fraction is efficiently degraded by biomass and that the membrane has an essential role in producing a permeate of excellent quality.

O proteassomo é uma protease intracelular multicatalítica envolvida na regulação do ciclo e sinalização celular, apresentação antigênica e apoptose. Uma vez que inibidores do proteassomo promovem morte celular por apoptose, esses têm sido propostos como novas drogas anti-tumorais. A terreína, um metabólito secundário secretado pelo fungo Aspergillus terreus, foi primeiramente descrita em 1935. Neste trabalho demonstramos que a terreína, isolada através da bioprospecção de inibidores do proteassomo, mostrou efeito inibitório das atividades do tipo quimiotripsina e tripsina da unidade catalítica do proteassomo 20S. Apesar da alta concentração inibitória determinada in vitro, aquela verificada após incubação de células em cultura na presença de terreína (fibroblasto e tumor pulmonar humano) foi 4 vezes menor, o que sugere que o proteassomo seja um alvo intracelular específico. A terreína promoveu morte celular por apoptose nas duas linhagens ensaiadas. Embora as concentrações de terreína necessárias para desencadear apoptose nos modelos celulares aqui testados tenham sido altas (ordem de mM) quando comparadas com doses utilizadas de outros inibidores descritos recentemente (ordem de μM e nM), sua estrutura química não está relacionada a nenhum outro inibidor conhecido até o momento. Concluímos que estes resultados apontam para a possibilidade de explorar a terreína como um novo fragmento molecular para o desenvolvimento de inibidores sintéticos do proteassomo.

The proteasome is an intracellular multicatalytic protease involved in the cell cycle regulation, signaling response, antigen presentation and apoptosis. Since proteasome inhibitors promote cell death by apoptosis, they have been proposed as new anti-tumoral drugs. Terrein, a secondary metabolite secreted by the fungus Aspergillus terreus, was firstly described in 1935. In the present work we report that terrein isolated through the screening for inhibitors of the 20S proteasome showed inhibitory effect upon both chymotrypsin- and trypsin-like activities of the multicatalytic core particle, the 20S proteasome. Despite of the high inhibitory concentration determined in vitro, that verified by incubating cells (fibroblasts and a pulmonary tumor cell line) in the presence of terrein was 4-fold lower indicating the proteasome as a selective intracellular target. Moreover, terrein promoted apoptotic cell death on both fibroblasts and pulmonary tumor cell line tested. Although terrein concentrations (mM range) necessary to elicit apoptosis in the cellular models herein tried were high when compared to those (μM and nM range) of other inhibitors recently described, its chemical structure is not correlated to any other inhibitor reported thus far. Therefore, the present results point out for the possibility of exploring terrein as a new molecular fragment for the development of synthetic proteasome inhibitors.