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This article analyses the performance of 166 wastewater treatment plants operating in Brazil, comprising six different treatment processes: septic tank þ anaerobic filter, facultative pond, anaerobic pond þ facultative pond, activated sludge, UASB reactors alone, UASB reactors followed by post-treatment. The study evaluates and compares the observed effluent quality and the removal efficiencies in terms of BOD, COD, TSS, TN, TP and FC with typical values reported in the technical literature. In view of the large performance variability observed, the existence of a relationship between design/operational parameters and treatment performance was investigated. From the results obtained, no consistent relationship between loading rates and effluent quality was found.The influence of loading rates differed from plant to plant, and the effluent quality was dictated by several combined factors related to design and operation.

SummarySplenectomy results in an increased risk of sepsis. The autogenous transplant of the spleen is an option for preserving splenic functions after total splenectomy. In this study, the capacity of animals undergoing autogenous spleen transplantation to respond to Staphylococcus aureus infection was investigated. BALB/c mice were divided into three groups: splenectomy followed by autotransplantation in the retroperitonium (AT), splenectomized only (SP) and operated non-splenectomized sham control (CT). Thirty days after surgery the mice were infected intravenously with S. aureus. Splenectomized mice had a higher number of colony-forming units (CFU) of S. aureus in liver and lungs in comparison with either AT or with CT mice (P < 0·05). Higher CFU numbers in lung of SP mice correlated with elevated production of interleukin-10 associated with a lower production of interferon-g and tumour necrosis factor-a. However, systemically, the level of tumour necrosis factor-a was higher in the SP group than in CT or AT. Lower titres of specific anti-S. aureus immunoglobulin (Ig)M and IgG1 were observed 6 days after infection in SP mice in comparison either with the AT or CT groups. Thus, splenectomy is detrimental to the immune response of BALB/c mice against infection by S. aureus which can be re-established by autogenous implantation of the spleen.

Restriction fragment length polymorphisms (RFLP) of ribosomal gene small subunit (SSU rDNA) and internal transcribed spacer (ITS) regions was examined in 12 isolates of dematiaceous agents of chromoblastomycosis and phaeohyphomycosis. The amplicon length of the fragment ITS1-ITS4, comprising the 5.8 rDNA and ITS1-ITS2 spacers, ranged in size from 620 to 690 bp. This result indicated a polymorphism of size in this region. Additionally the RFLP profiles showed a high degree of inter- and intra-specific variability. In contrast, the SSU rDNA amplification, using NS1-NS2 primers, originated a fragment of approximately 570 bp and its restriction profile proved to be well conserved among the species studied and was clustered into only two genetically heterogeneous groups, the first one formed by Fonsecaea pedrosoi and Fonsecaea compacta and the second one formed by Cladophialophora (Cladosporium) carrionii, Cladophialophora (Xylohypha) bantiana, Phialophora verrucosa and Rhinocladiella species.

Aim: To analyse the influence of ethylenediaminetetraacetic acid (EDTA) on the repair process in immature rat molars after a regenerative endodontic procedure (REP). Methodology:The lower first molars of 12 4-week-old Wistar rats underwent pulpectomy in the mesial root and were divided into the following groups: sodium hypochlorite (NaOCl; n = 6) -the mesial canals were irrigated with 2.5% NaOCl for 5 min, and NaOCl-EDTA (n = 6) -the canals were irrigated with 2.5% NaOCl, followed by 17% EDTA for 5 min each. After evoking bleeding using a size 10 K-file, the cavities were sealed. Three molars on the untreated side were randomly used as control (control-15 d; n = 3), and three molars from the other three rats untreated were used as immediate control (n = 3). After 15 days (NaOCl, NaOCl-EDTA and control-15 d groups) or immediately (control-immediate), the animals were euthanized, and the teeth were subjected to histologic evaluation of tissue regeneration and presence of collagen fibres. Mann-Whitney U-test was used (p < .05). Results:The experimental groups had newly formed cementum-like tissue and increased root length and thickness. Half of the specimens in NaOCl-EDTA group showed apical foramen closure, whilst the NaOCl group had partial apical closure.The experimental groups showed inflammatory infiltrate extending mainly to the medium third of the root canal. These parameters were similar between experimental groups (p > .05). Newly formed connective tissue in the pulp space was significantly higher in the NaOCl-EDTA group than in NaOCl group (p < .05). Regarding the collagen fibres, the NaOCl-EDTA group had more collagen fibres in the root tip, but there was no significant difference compared to NaOCl group, and both groups showed greater amount of immature fibres in this area; in the centre of the apical third of root canal, there was equivalence between mature and immature fibres from both groups (p > .05).

RESUMOEste artigo apresenta uma análise da confiabilidade de 166 estações de tratamento de esgotos em operação no Brasil, considerando seis processos de tratamento mais usualmente adotados. Foi utilizada uma metodologia desenvolvida por Niku et al (1979) ARTIGO TÉCNICO INTRODUÇÃOA confiabilidade de um sistema pode ser definida como a probabilidade de se conseguir um desempenho adequado por um período específico de tempo, sob determinadas condições.Em termos de desempenho de uma estação de tratamento, a confiabilidade pode ser entendida como a porcentagem de tempo em que se conseguem as concentrações esperadas no efluente para cumprir com os padrões de lançamento. Assim, uma ETE será completamente confiável se não houver falha no desempenho, ou seja, se não houver violação dos limites preconizados pelas legislações ambientais. A falha do processo de tratamento ocorrerá sempre que o padrão de lançamento for excedido.Devido às inúmeras incertezas presentes no projeto e operação de estações de tratamento, existem alguns riscos de falha que são inevitáveis e as ETEs devem ser projetadas com base em uma medida aceitável de risco ou violação.A probabilidade de falha é extremamente sensível à função de distribuição da concentração efluente. Conhecida esta distribuição, uma expressão pode ser utilizada para definir a fração do tempo em que uma dada concentração foi excedida no passado e, desta forma, predizer o comportamento futuro de uma ETE, desde que as variá-veis do processo continuem as mesmas (Dean & Forsythe, 1976a).A exigência mínima de confiabilidade deve ser determinada para estabelecer a magnitude da probabilidade de falha que poderá ser aceita. Para esta determinação, Niku et al (1981b) citam uma teoria de decisão estatísti-ca-econômica, que estabelece que os custos totais de estações de tratamento, considerando a construção, a operação e o valor do custo de falha multiplicado pela probabilidade de sua ocorrência, devem ser mínimos.Os custos inicial e operacional do processo poderão sofrer grandes alterações, dependendo da confiabilidade desejada. Quando existem grandes expectativas com respeito à qualidade do efluente, poderá haver necessidade de modernos sistemas de controle, mão de obra mais especializada, exigência de tratamento terciário e/ou expansão física da estação. Qualquer uma destas modificações aumentará o custo inicial de construção e de operação.

This article evaluates and compares the actual behavior of 166 full-scale anaerobic and aerobic wastewater treatment plants in operation in Brazil, providing information on the performance of the processes in terms of the quality of the generated effluent and the removal efficiency achieved. The observed results of effluent concentrations and removal efficiencies of the constituents BOD, COD, TSS (total suspended solids), TN (total nitrogen), TP (total phosphorus) and FC (faecal or thermotolerant coliforms) have been compared with the typical expected performance reported in the literature. The treatment technologies selected for study were: (a) predominantly anaerobic: (i) septic tank + anaerobic filter (ST + AF), (ii) UASB reactor without post-treatment (UASB) and (iii) UASB reactor followed by several post-treatment processes (UASB + POST); (b) predominantly aerobic: (iv) facultative pond (FP), (v) anaerobic pond followed by facultative pond (AP + FP) and (vi) activated sludge (AS). The results, confirmed by statistical tests, showed that, in general, the best performance was achieved by AS, but closely followed by UASB reactor, when operating with any kind of post-treatment. The effluent quality of the anaerobic processes ST + AF and UASB reactor without post-treatment was very similar to the one presented by facultative pond, a simpler aerobic process, regarding organic matter.

This article evaluates and compares the actual behavior of 18 UASB reactor systems operating without (10 plants) and with (8 plants) post treatment, considering their performance and their reliability in terms of compliance with specified discharge standards. The following types of post-treatment processes were analyzed: aerated filter; anaerobic filter; trickling filter; dissolved air flotation unit; facultative pond and maturation pond. The effluent quality and the removal efficiencies were compared with typical values reported in the technical literature. A methodology developed by Niku et al. (1979) was used for the determination of the coefficients of reliability, in terms of the compliance of effluent BOD and TSS with discharge standards. The results showed that, in general, the inclusion of a post-treatment step, be it either aerobic, anaerobic or physical-chemical, can provide a substantial improvement of the effluent quality from UASB reactors in terms of BOD and TSS. In terms of the systems reliability, the actual effluent concentrations from UASB reactor followed by some post-treatment processes would meet more restrictive discharge standards than those considered in this study (60 mg L(-1) for both constituents-values prevailing in most states in Brazil).