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The objective of this work was to develop a polymeric structure for a biofiltration unit of domestic effluents through microbiological immobilization, capable of promoting the efficient removal of pollutants, meeting local/national Brazilian standards and/or legislation while providing low environmental impact on their production. Four different structures were tested, namely, polypropylene casings without filling material (TF1); polypropylene casings filled with expanded polystyrene grains (TF2); polypropylene casings, filled with polyurethane foam (TF3); and polypropylene casings, filled with polyvinyl chloride pellets (TF4). A flow of 0.216 m3 d-1 was applied to the system, and the biofilters operated in sequential batches with a hydraulic retention time of 6 h. The efficiency potential of the four immobilization structures was verified regarding biochemical and chemical oxygen demand, total ammoniacal nitrogen and total phosphorus. Microbiological analysis of the formed biofilm, performed with the 16S library sequencing method, with amplification of the 16S rRNA V3 and V3-V4 genomic regions, showed a high diversity of microbiological colonization in the four immobilization structures, with better results and consequently greater community stability in TF2. It is recommended using the filter bed made up of unfilled casings, followed by the one filled with expanded polystyrene grains.

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The evaluation of contamination by domestic sewage is relevant in the Amazon region; however, it has neither been well-developed nor accompanied by research or monitoring programs. In this study, caffeine and coprostanol as indicators of sewage were investigated in water samples from Amazonian water bodies that crisscross the city of Manaus (Amazonas state, Brazil) and cover regions with distinct main land uses such as high-density residential, low-density residential, commercial, industrial, and environmental protection areas. Thirty-one water samples were studied based on their dissolved and particulate organic matter (DOM and POM) fractions. Quantitative determination of both caffeine and coprostanol was carried out using LC-MS/MS with APCI in the positive ionization mode. The streams of the urban area of Manaus had the highest concentrations of caffeine (1.47-69.65 µg L-1) and coprostanol (2.88-46.92 µg L-1). Samples from the peri-urban Tarumã-Açu stream and from the streams in the Adolpho Ducke Forest Reserve showed much lower concentrations of caffeine (20.20-165.78 ng L-1) and coprostanol (31.49-120.44 ng L-1). Samples from the Negro River showed a wider range of concentrations of caffeine (20.59-873.59 ng L-1) and coprostanol (31.72-706.46 ng L-1), with the highest values found in the outfalls of the urban streams. Levels of caffeine and coprostanol were significantly positively correlated in the different organic matter fractions. The coprostanol/(coprostanol + cholestanol) ratio proved to be a more suitable parameter than the coprostanol/cholesterol one in low-density residential areas. Proximity to densely populated areas and the flow of water bodies appear to influence the caffeine and coprostanol concentrations, which was observed in their clustering in the multivariate analysis. The results indicate that caffeine and coprostanol can be detected even in water bodies that receive very low domestic sewage input. Therefore, this study revealed that both caffeine in DOM and coprostanol in POM represent viable alternatives for use in studies and monitoring programs even in remote areas of the Amazon, where microbiological analyses are often unfeasible.

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The pollution of the surface waters by pharmaceuticals and personal care products (PPCPs) has attracted worldwide attention, but data regarding their occurrence and potential risks for the aquatic biota on tropical coastal rivers of South America are still scarce. In this context, the occurrence and the preliminary ecological risk assessment of eleven pharmaceuticals of various therapeutic classes (including cocaine and its primary metabolite, benzoylecgonine) were investigated, for the first time, in five rivers of São Paulo, southeast Brazil, covering a coastline of about 140 km, namely Perequê River, Itinga River, Mongaguá River, Itanhaém River and Guaraú River. Although these five rivers are born in well-preserved areas of the Atlantic rainforest biome, on its way to sea and when they cross the urban perimeter, they receive untreated sewage discharges containing a complex mixture of contaminants. In addition, a "persistence, bioaccumulation and toxicity" (PBT) approach allowed to pre-select the priority PPCPs to be monitored in this coastline. Identification of several PPCPs in the samples was done using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Ten PPCPs were successfully quantified in all five rivers, namely caffeine (9.00-560.00 ng/L), acetaminophen (

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Domestic wastewater is an important alternative source of water in the face of a growing discrepancy between water availability and demand. The use of techniques that enable the urban reuse of treated sewage is essential to make cities more sustainable and resilient to water scarcity. The main goal of this study was to evaluate the performance of an electrocoagulation-flotation system in the treatment of domestic wastewater for urban reuse. The study was performed using raw domestic wastewater samples. The electrocoagulation-flotation system was a cylindrical reactor with aluminum electrodes. The treatment conditions involved agitation at 262.5 rpm, electrical current of 1.65 A, electrolysis time of 25 min, an initial pH of 6, and inter-electrode distance of 1 cm. Overall, the electrocoagulation-flotation system was highly efficient for removal of apparent color (97.9%), chemical oxygen demand (82.9%), turbidity (95.8%), and orthophosphate phosphorous (> 98.2%). The electrocoagulation-flotation system had a consumption of electrical energy ranging from 9.5 to 13.3 kWh m-3, electrode mass from 294.7 to 557.0 g m-3, and hydrochloric acid from 4.3 to 6.6 L m-3. Sludge production in the system ranged from 1,125.7 to 1,835.7 g m-3. Treated wastewater had a satisfactory quality for several urban reuse activities. The electrocoagulation-flotation system showed potential to be used for domestic wastewater treatment for urban reuse purposes.

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"Wealth by the sea and poverty away from the sea breeze" is a metaphor that mirrors what happens along the Brazilian coastal zone, namely in São Vicente Island, São Paulo, Brazil. Due to the high cost of the properties on this shore, the impoverished population started to migrate to the northern outskirts of the island (away from the tourist beaches), potentiating the emergence of poor housing conditions, namely stilt-house slums. Consequently, the urban drainage channels across these outskirts neighbourhoods are potentially contaminated by human wastes. In this context, the occurrence and preliminary ecological risk assessment of eleven pharmaceuticals of various therapeutic classes (including cocaine and its primary metabolite, benzoylecgonine) were investigated, for the first time, in five urban drainage channels whose diffuse loads flow continuously to the estuarine waters of São Vicente Island. The results showed the widespread presence of these environmental stressors in all urban channels analysed, namely losartan (7.3-2680.0 ng/L), caffeine (314.0-726.0 ng/L), acetaminophen (7.0-78.2 ng/L), atenolol (6.2-23.6 ng/L), benzoylecgonine (10.2-17.2 ng/L), furosemide (1.0-7.2 ng/L), cocaine (2.3-6.7 ng/L), carbamazepine (0.2-2.6 ng/L), diclofenac (1.1-2.5 ng/L), orphenadrine (0.2-1.1 ng/L) and chlortalidone (0.5-1.0 ng/L). The overall total estimated load of pharmaceuticals and personal care products flowing to the estuarine waters of São Vicente Island is on the order of 41.1 g/day. The ecological risk assessment revealed a great environmental concern for São Vicente Island, ranging between low (e.g. carbamazepine and cocaine) and moderate to high (e.g. caffeine, acetaminophen and losartan) threats for the aquatic biota. Therefore, initiatives promoting basic sanitation, land-use regularisation and population awareness are highly recommended.

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RESUMO Diversos trabalhos têm mostrado a formação de lodo granular aeróbio em reatores nos quais são impostas elevadas velocidades de sedimentação, da ordem de 10 a 12 m.h−1. Aparentemente, quando a velocidade de sedimentação é inferior a 3,8 m.h−1, a fração de lodo floculado é predominante, visto que o lodo suspenso não é eliminado de forma efetiva do reator. Outros estudos, entretanto, mostram a formação de lodos granulares aeróbios para velocidades menores que essa, apontando a possibilidade da formação desse tipo de biomassa em velocidades ainda menores. Assim, este trabalho avaliou a formação desse tipo de lodo em reatores que tratam esgoto sanitário, com relação altura/diâmetro unitária, para velocidades de sedimentação de 1,8 e 1,2 m.h−1, verificando as eficiências de remoção de matéria orgânica e nitrogênio. Os resultados obtidos indicaram que é possível formar lodo aeróbio granular para a faixa de velocidade de estudo, porém com baixa estabilidade estrutural para diâmetros de 1,2 mm ou mais. Essa instabilidade dos grânulos contribui para a baixa eficiência de remoção de matéria orgânica e nitrogênio nos reatores.

ABSTRACT Several studies have shown the formation of aerobic granular sludge in reactors where high sedimentation rates are imposed, varying from 10 to 12 m.h−1. Apparently, when the settling velocity is less than 3.8 m.h−1, the fraction of flocculated sludge is predominant, since the suspended sludge is not effectively eliminated from the reactor. Other studies, however, show the formation of aerobic granular sludge at velocities lower than this, pointing to the possibility of formation of this type of biomass at even lower speeds. Thus, this work evaluated the efficacy of this type of sludge in reactors treating sewage, with H/D ratio (height/diameter), for sedimentation velocities of 1.8 and 1.2 mh−1, verifying the efficiencies of organic matter and nitrogen. The results indicated that it is possible to form aerobic granular sludge for the study velocity range, but with low structural stability from diameters of approximately 1.2 mm. This instability of the granules contributes to the low efficiency of removal of organic matter and nitrogen in the reactors.

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RESUMO A remoção de matéria orgânica e de nitrogênio em esgoto doméstico diluído foi avaliada em dois reatores híbridos, um anaeróbio (RHAN) e outro aeróbio (RHAE). O RHAN era formado por uma câmara tipo upflow anaerobic sludge blanket sobreposta por outra de filtro anaeróbio, enquanto o RHAE tinha uma câmara de lodo ativado sobreposta por outra de biofilme aerado submerso. A operação do sistema foi dividida em duas fases, FI e FII, com razões de recirculação de 50 e 75% e duração de 94 e 110 dias, respectivamente. Para a remoção de nitrogênio, o RHAE foi operado com oxigênio dissolvido de 3,0 mg.L-1. A técnica da reação em cadeia da polimerase foi empregada tanto para o lodo suspenso das câmaras inferiores, como para o biofilme aderido nas câmaras superiores, para identificar a presença de micro-organismos desnitrificantes e nitrificantes. As maiores eficiências de remoção em termos de demanda química de oxigênio e nitrogênio total foram obtidas em FII, sendo 91% e ~50%, respectivamente; as concentrações no efluente foram ~40 mg O2.L-1 e ~15 mg N-NT.L-1. A presença de três grupos de bactérias, as desnitrificantes, as oxidantes de amônia e as oxidantes de nitrito, foi confirmada no biofilme aderido do RHAE, indicando uma biomassa mixotrófica e sugerindo a possibilidade do processo de nitrificação e desnitrificação simultânea.

ABSTRACT The removal of organic matter and nitrogen in diluted domestic sewage was evaluated in two hybrid reactors, one anaerobic (ANHR) and another aerobic (AEHR). ANHR was formed by a upflow anaerobic sludge blanket (UASB)-type chamber overlaid by an anaerobic filter, while AEHR had an activated sludge chamber overlaid by a submerged aerated biofilm chamber. The experimental period was divided into two phases, FI and FII, with recirculation ratios of 50 and 75%, and duration of 94 and 110 days, respectively. For nitrogen removal, AEHR was operated with a 3.0-mg.L-1 dissolved oxygen. Polymerase chain reaction technique was used for both suspended sludge in the down-chambers and attached biofilm in the upper-chambers, to identify the presence of denitrifying and nitrifying microorganisms. The highest removal efficiencies in terms of chemical oxygen demand and total nitrogen were obtained in FII, being 91 and ~50%, respectively; effluent concentrations were ~40 mg O2.L-1 and ~15 mg N-TN.L-1. The presence of three groups of bacteria, the denitrifiers, the ammonia oxidants and the nitrite oxidants, was confirmed in the attached biofilm of the RHAE, indicating a mixotrophic biomass and suggesting the possibility of simultaneous nitrification and denitrification process.

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To investigate the feasibility of implementing decentralized sewage treatment systems aiming to meet environmental standards, the performance of three decentralized wastewater treatment plants (WWTPs) comprising septic tanks and anaerobic filters (ST+AF) was evaluated. The ability of the WWTPs to comply with the provisions of the legislation and the technical literature was investigated by monitoring physical and chemical parameters at the entrance and exit of the WWTPs, from May 2017 to August 2018. Considering that factors such as operational routine, design of treatment systems, and the existence of pluvial contributions to the sewage network can influence the performance of WWTPs, an investigation of these factors was conducted. The results show that the ST+AF systems can meet the requirements of the legislation. The hypothesis raised in this study is that factors such as cleaning routine and dimensioning of the treatment units can influence the performance of the systems. The best performance was found in the WWTP submitted to frequent cleaning and whose ST dimensions were closest to those recommended by technical standards. The average annual efficiencies of removal of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) in this WWTP assumed values of 93 and 89%, while its solid effluents presented concentrations 82% below the limit established in legislation. Finally, no rainwater contributions were found in the WWTPs, which may be associated with the use of short collection networks in decentralized systems.

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Sewage treatment and water reuse are, undoubtedly, one of the main points on scientific agenda of the 21st century. Many technologies for sewage treatment are available; however, it is still as an open issue that deserves much attention in order to facilitate their application, develop more effective methods and propose alternative treatment for unusual situations. Developing high performance materials for sewage treatment fits the idea of the development of efficient and alternative methods for microorganism removal and the high organic load of wastewater and is of fundamental importance. In this paper, a heterojunction with perovskite-type strontium stannate (SrSnO3) and graphitic carbon nitride (g-C3N4) - SrSnO3/g-C3N4 - was synthesized and used for photocatalytic treatment of domestic sewage using only sunlight. Results were accompanied by assessing the total organic carbon decrease and removal of pathogenic microorganisms. X-ray diffraction and X-ray excited photoelectron spectroscopy demonstrated that a heterostructure was successfully formed and photocatalytic tests showed an important activity in the visible range, i.e., under sunlight. Exposing raw sewage to 240 min (from 11 a.m. until 3 p.m.) in the presence of SrSnO3/g-C3N4, led to a 56.1% mineralization. This process was 2.5 more efficient than photolysis under sunlight. Moreover, the treated sewage showed no coliform growth (either fecal or total) or heterotrophic bacteria. This simple treatment makes sewage suitable and safe for reuse, for example, for agriculture purposes according to Brazilian regulations criteria and could be an alternative for isolated areas in which sewage treatment plants are not available.

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RESUMO Nas últimas décadas se intensificou o lançamento, no meio hídrico, de contaminantes com capacidade de desregulação endócrina. Nesse contexto, a aplicação e o aprimoramento de métodos analíticos eficientes passam a ser cada vez mais requeridos para verificar os potenciais impactos dessas substâncias sobre os organismos a elas expostos. Bioensaios podem ser conduzidos para esse fim, como, por exemplo, o ensaio in vitro yeast estrogen screen (YES), que permite a detecção de compostos estrogênicos e citotóxicos. Este estudo, aplicando tal ensaio, investigou a atividade estrogênica das águas e seus potenciais riscos à biota aquática de dois corpos hídricos do município de Santa Maria Madalena, no estado do Rio de Janeiro, Sudeste do Brasil. Observou-se atividade estrogênica apenas no córrego São Domingos, com concentrações de equivalente estradiol (EQ-E2) de 23 e 10.4 ng.L−1 no período de estiagem e chuvoso, respectivamente. Os potenciais riscos desse nível de atividade estrogênica foram mensurados por meio de uma avaliação de risco, que revelou alto e médio risco nas estações seca e chuvosa, respectivamente. Cabe mencionar que, entre os corpos hídricos estudados, a área do córrego São Domingos é aquela com maior adensamento populacional e menor cobertura de coleta e tratamento de esgotos. O ensaio YES mostrou ser uma boa ferramenta para a detecção da presença de desreguladores endócrinos estrogênicos, que pode subsidiar o avanço do conhecimento de corpos hídricos e a formulação de legislação e regulamentações da área ambiental.

ABSTRACT In recent decades, the release of contaminants with endocrine disrupting capacity into the water environment has intensified. In this context, the application and improvement of efficient analytical methods are increasingly required to verify the potential impacts of these substances on the organisms exposed to them. Bioassays can be conducted with this purpose, such as the yeast estrogen screen (YES) in vitro assay, which allows the detection of estrogenic and cytotoxic compounds. This study, applying the YES assay, investigated the estrogenic activity and its potential risks to the aquatic biota of two streams in Santa Maria Madalena, Rio de Janeiro State, Southeastern Brazil. Estrogenic activity was observed only in São Domingos stream, with estradiol equivalent (EEQ) concentrations of 23 and 10.4 ng.L−1 during the dry and rainy season, respectively. The potential risks of this level of estrogenic activity were evaluated by a risk assessment, which revealed a high and medium risk to the local biota in the dry and rainy seasons, respectively. Among the studied water bodies, São Domingos watershed has a bigger population density and less sewage collection and treatment comparatively to Ribeirão Santíssimo stream. The YES assay presented itself as a useful tool for spotting estrogenic endocrine disruptors, with the potential to help in expanding knowledge about water bodies and to create and enforce environmental legislation and regulations.

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The risks inherent to the inadequate domestic wastewater disposal, allied to the water growing demand, scarcity, and pollution problems, have highlighted the importance of adopting treatment techniques that not only target the sewage discharge, but also its reuse. For this reason, the objective of this study was to evaluate the best conditions of an electrocoagulation-flotation system for domestic wastewater treatment and urban reuse. To achieve this, an effects study followed by two rotatable central composite experimental designs 2² was performed, considering: agitation, electrical current, electrolysis time, inter-electrodes distance, and initial pH. The electrocoagulation-flotation system was composed of a cylindrical acrylic reactor with a working volume of 1 L, with two aluminium electrodes connected to a direct-current power supply. Results showed that electrical current and electrolysis time were the most influent operational parameters on domestic wastewater treatment in the electrocoagulation-flotation system. The initial pH adjustment was also important due the pH increase tendency observed in the results. The best conditions of agitation, inter-electrodes distance, electrolysis time, electrical current, and initial pH for domestic wastewater treatment and urban reuse were 262.5 rpm, 1 cm, 25 min, 1.65 A, and 6, respectively. Under these conditions, turbidity and colour removals higher than 98% and 92% were reached respectively, as well as residual turbidity lower than 6 NTU and final pH of 8 were achieved, following the Brazilian standards and guidelines for urban reuse. Thus, the electrocoagulation-flotation system studied was effective for domestic wastewater treatment and reuse for urban supply purposes.

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Over the last decades, the Rodrigo de Freitas Lagoon (RFL), Rio de Janeiro, Brazil, has been impacted by the release of untreated domestic sewage, causing eutrophication processes with negative effects on its biota. Recently, the RFL underwent urban interventions to fulfill the demands of the 2016 Olympic Games, which included building the waist gallery and monitoring clandestine waste discharges into the underground drainage network. Organic-source tracing methods can be successfully used to characterize the organic matter transported from the urbanized areas to the RLF. The application of the elemental (C, N) and stable isotope (δ15N and δ13C) fingerprint methods in sediments from the RLF indicated a reduction in the domestic sewage inputs from 32 ± 16 to 12 ± 13% between 2015 and 2017. However, the sewage inputs continue being worrying. Our results also suggest that the main source of organic matter pollution in the lagoon comes from indiscriminate domestic sewage release from river channels. Secondary pollution sources are associated with the underground drainage network that still shows punctual and irregular releases of domestic sewage. Petroleum products, mainly from sewers, also show as possible organic pollution sources. Finally, the findings indicate that the interventions carried out in the RFL are promising. However, they were insufficient to cease the pollutant inputs and mitigate the negative impacts of eutrophication.

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Aerobic granular sludge (AGS) has been considered a breakthrough in the wastewater treatment sector given its key characteristics, such as excellent settleability, simultaneous removal of organic and nutrient pollutants, and compactness. However, the formation of granules often delays the start-up of granular-based systems, especially in large-scale settings. This study addressed the start-up of a pilot-scale AGS sequencing batch reactor (SBR) treating domestic sewage, monitored for over 280 days. The challenges faced during aerobic granulation using a mixture of activated sludge and anaerobic granular sludge as inoculum and the performance of the reactor on organic matter, nitrogen, and phosphorus removal were discussed. Results showed that robust and stable granules were formed after an initial period of around six months, with the settling time playing a key role on granules development. At least 80% of granules had a diameter greater than 0.2 mm and 60% >1 mm. In general, the reactor achieved high nitrogen removal efficiency, as well as satisfactory removal of soluble COD. However, total COD abatement was impaired by the various episodes of suspended solids loss with the effluent. Overall, this study demonstrated that the reactor was efficient in the treatment of domestic sewage, but its performance was adversely affected from sudden changes in the influent quality. PRACTITIONER POINTS: Aerobic granular sludge (AGS) applied to small-scale domestic sewage treatment. The control of sludge age in AGS can be a problem due to short sedimentation times. High DO to maintain aerobic granulation can economically make the process economically unfeasible in tropical countries. A sludge with excellent sedimentation properties was obtained. However, maintaining the granule over time is a challenge.

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An accurate and sensitive ultrasound-dispersive liquid-liquid microextraction technique followed by high-performance liquid chromatography separation coupled with electrospray ionization tandem mass spectrometry detection method to determine the presence of tetrabromobisphenol A (TBBPA) in complex environmental matrices is proposed. The miniaturized procedure was used to extract and quantify the analyte in domestic sewage, anaerobic sludge, and the aquatic test organism species Daphnia magna and Chironomus sancticaroli, which are standardized organisms for ecotoxicity bioassays. Limits of detection of 2 ng L-1 (domestic sewage), 2 ng g-1 (anaerobic sludge), 0.25 ng g-1 (D. magna), and 5 ng g-1 (C. tentans) were obtained. The presence of TBBPA was determined in domestic sewage and anaerobic sludge from an anaerobic batch bioreactor at a concentration of 0.2 ± 0.03 µg L-1 and 507 ± 79 ng g-1 , respectively. In D. magna and C. sancticaroli exposed to TBBPA in an acute toxicity bioassay, the micropollutant accumulated at 3.74 and 8.87 µg g-1 , respectively. The proposed method is a simple and cost-effective tool to determine TBBPA environmental occurrence and biomagnification potential compared with conventional extraction methods. To the best of our knowledge, this is the first liquid-liquid miniaturized extraction method to be applied to D. magna and C. sancticaroli. Environ Toxicol Chem 2020;39:2147-2157. © 2020 SETAC.

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The occurrence of pharmaceuticals and illicit drugs in water resources is widely documented in Europe, North America and Asia. However, in South America, these studies are still incipient. The objective of this study was to screen and identify the presence of pharmaceuticals of various therapeutic classes, including illicit drugs such as cocaine and its metabolite benzoylecgonine, in urban drainage channels that flow into the bathing waters of Guarujá city, State of São Paulo, Brazil. Moreover, the ecological potential risks to the aquatic biota were also assessed. The water samples were collected from four beaches of Guarujá in two different points: in the urban drainage channels and in the nearby coast line. A total of 16 compounds were detected using liquid chromatography coupled with tandem mass spectrometry: carbamazepine (0.1-8.0 ng/L), caffeine (33.5-6550.0 ng/L), cocaine (0.2-30.3 ng/L), benzoylecgonine (0.9-278.0 ng/L), citalopram (0.2-0.4 ng/L), acetaminophen (18.3-391.0 ng/L), diclofenac (0.9-79.8 ng/L), orphenadrine (0.2-1.5 ng/L), atenolol (0.1-140.0 ng/L), propranolol (limit of detection: LOD-0.9 ng/L), enalapril (2.2-3.8 ng/L), losartan (3.6-548.0 ng/L), valsartan (19.8-798.0 ng/L), rosuvastatin (2.5-38.5 ng/L), chlortalidone (0.1-0.4 ng/L) and clopidogrel (0.1-0.2 ng/L). The hereby data also showed that five of these compounds, namely caffeine, acetaminophen, diclofenac, losartan and valsartan, could raise moderate to severe risks to aquatic organisms (algae, crustaceans and fishes). This study is the first report of the occurrence of several pharmaceuticals and illicit drugs in urban drainage channels that flow to the bathing waters in South America, and it is the first quantification of rosuvastatin, chlortalidone and clopidogrel in environmental marine waters of Latin America.

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The ADNMED (Anaerobic Digestion, Nitrification, and Mixotrophic Endogenous Denitrification) system comprises a triple chamber configuration that was shown to provide high-quality effluent regarding carbon, nitrogen, and sulfide. Hydraulic retention time (HRT) was 7 h in the anaerobic and anoxic chambers, and 5 h in the aerobic chamber (stage A). Sewage was directly added to the anoxic chamber to provide extra organic electron donors for denitrification (stage B) to improve the nitrogen removal efficiency (stage A 47 ± 19%). The addition of sewage at a flow rate equivalent to 10% of the feed flow increased nitrogen removal efficiency to 61 ± 12%. Illumina® sequencing revealed a restructuring of the microbial community in the anoxic chamber, according to the availability of the endogenous electron donors for denitrification. At stage A, denitrification was related to the decay of biomass, while the addition of sewage during stage B stimulated the establishment of fermentative bacteria.

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RESUMO Sistemas anaeróbios modernos de tratamento de esgoto doméstico, embora bastante eficientes na remoção de matéria orgânica e sólidos em suspensão, não produzem um efluente com qualidade compatível com os padrões legais para descarga em corpos d'água. Por essa razão, esses sistemas têm de ser associados a unidades de pós-tratamento. Este trabalho trata de uma investigação experimental sobre a viabilidade de aplicação do sistema de lodo ativado como uma alternativa do pós-tratamento, especificamente para o caso em que se prevê o efluente final para fertirrigação. Na investigação experimental, utilizou-se um reator de bateladas sequenciais (RBS), em escala laboratorial, como unidade de pós-tratamento. Os resultados experimentais mostraram que o comportamento do sistema RBS pode ser descrito como o modelo geral de lodo ativado da Associação Internacional da Água (IWA, na sigla em inglês), que resulta na definição dos aspectos fundamentais: qualidade do efluente final, consumo de oxigênio e produção de lodo. Na otimização do reator RBS, desenvolveu-se um modelo que permite estabelecer o tempo de permanência mínimo para o pós-tratamento em função de dois parâmetros básicos: a constante de utilização de material orgânico biodegradável pelas bactérias heterotróficas do lodo gerado no sistema de pós tratamento e a sedimentabilidade desse lodo. A constante de utilização de material orgânico foi determinada por testes respirométricos. O lodo gerado no sistema de pós-tratamento surpreendentemente mostrou ter uma sedimentabilidade bem superior àquela normalmente encontrada em sistemas de lodo ativado tratando esgoto bruto, o que constitui um argumento sólido para a aplicação do sistema RBS na prática de pós-tratamento do efluente do reator upflow anaerobic slugde blanket (UASB).

ABSTRACT Modern anaerobic systems for domestic sewage treatment, although very effective in removing organic matter and suspended solids, do not produce a quality effluent that complies with the legal standards for discharge into water bodies. Therefore, such systems have to be associated with post treatment units. This paper deals with an experimental investigation into the feasibility of applying the activated sludge system as an alternative post-treatment, specifically for the case where reuse of the final wastewater for fertigation is expected. In the experimental investigation, a pilot-scale sequencing batch reactor (SBR), in laboratory scale, was used as a post-treatment unit. The experimental results showed that the behavior of the RBS system can be described with the general IWA model for activated sludge, resulting in the definition of the fundamental aspects: quality of the final effluent, oxygen consumption, and sludge production. In the optimization of the RBS reactor, a model was developed to establish the minimum retention time for the post-treatment in terms of two basic parameters: the biodegradable organic material utilization constant by heterotrophic bacteria sludge of the post-treatment system and the sedimentability of this sludge. The organic material utilization constant was determined by respirometry testing. The sludge generated in the post-treatment system surprisingly been shown to have a much higher sedimentability than that normally found in activated sludge systems dealing with raw sewage, which is a sound argument for applying the RBS system in the practice of post-treatment reactor effluent UASB

RESUMO

A proteção e o uso adequado das fontes de água potável no planeta devem ser buscadas de forma exaustiva para a conservação da vida na terra. O processo de industrialização e crescimento demográfico acaba por tornar ainda mais preocupante a manutenção das reservas hídricas para garantir o desenvolvimento sustentável. Frente a esse desafio, cada vez mais os ramos da engenharia ligados à área ambiental vêm desenvolvendo novos métodos de tratamento do esgoto de forma a alcançar a manutenção da água para as futuras gerações. Entre as novas tecnologias em estudo tem-se o sistema de filtração lenta que a partir da utilização de reservatórios com camadas de areia e pedra de tamanhos distintos possibilitam por processos físico-químicos a depuração do esgoto. A presente pesquisa buscou monitorar e avaliar a concentração de oxigênio dissolvido em um sistema de filtros lentos com e sem carvão ativado projetado e instalado na UNICAMP. Durante as nove semanas de estudo os resultados alcançados foram de eficiência no ganho de oxigênio dissolvido no filtro com e sem carvão ativo de 90,67% e 49,50%, respectivamente.(AU)

The protection and proper use of drinking water sources on the planet should be pursued in an exhaustive way for the conservation of life on earth. The process of industrialization and population growth have made the maintenance of water reserves even more worrisome to ensure sustainable development. Faced with this challenge, more and more the engineering branches related to the environmental area have been developing new methods of treatment of the sewage in order to reach the maintenance of water for future generations. Among the new technologies under study is the slow filtration system which, through theuse of reservoirs with layers of sand and stone of different sizes, enables the purification of sewage by physico-chemical processes. The present research sought to monitor and evaluate the concentration of dissolved oxygen in a systemof slow filters with and without activated carbon designed and installed in UNICAMP. During the nine weeks of study, the results obtained were of efficiency in the gain of oxygen dissolved in the filter with and without active carbon of 90.67% and 49.50%, respectively.(AU)

Assuntos

RESUMO

A proteção e o uso adequado das fontes de água potável no planeta devem ser buscadas de forma exaustiva para a conservação da vida na terra. O processo de industrialização e crescimento demográfico acaba por tornar ainda mais preocupante a manutenção das reservas hídricas para garantir o desenvolvimento sustentável. Frente a esse desafio, cada vez mais os ramos da engenharia ligados à área ambiental vêm desenvolvendo novos métodos de tratamento do esgoto de forma a alcançar a manutenção da água para as futuras gerações. Entre as novas tecnologias em estudo tem-se o sistema de filtração lenta que a partir da utilização de reservatórios com camadas de areia e pedra de tamanhos distintos possibilitam por processos físico-químicos a depuração do esgoto. A presente pesquisa buscou monitorar e avaliar a concentração de oxigênio dissolvido em um sistema de filtros lentos com e sem carvão ativado projetado e instalado na UNICAMP. Durante as nove semanas de estudo os resultados alcançados foram de eficiência no ganho de oxigênio dissolvido no filtro com e sem carvão ativo de 90,67% e 49,50%, respectivamente.

The protection and proper use of drinking water sources on the planet should be pursued in an exhaustive way for the conservation of life on earth. The process of industrialization and population growth have made the maintenance of water reserves even more worrisome to ensure sustainable development. Faced with this challenge, more and more the engineering branches related to the environmental area have been developing new methods of treatment of the sewage in order to reach the maintenance of water for future generations. Among the new technologies under study is the slow filtration system which, through theuse of reservoirs with layers of sand and stone of different sizes, enables the purification of sewage by physico-chemical processes. The present research sought to monitor and evaluate the concentration of dissolved oxygen in a systemof slow filters with and without activated carbon designed and installed in UNICAMP. During the nine weeks of study, the results obtained were of efficiency in the gain of oxygen dissolved in the filter with and without active carbon of 90.67% and 49.50%, respectively.

Assuntos

RESUMO

Abstract This study assessed the performance of two pilot units, a conventional activated sludge (CAS) and an Integrated Fixed-Film Activated Sludge (IAS), in the treatment of leachate from sanitary landfill combined with domestic sewage, with the aim of removing organic substances. In order to assess the possible impacts on treatment, three experimental phases were designed using influent leachate contributions of 5%, 10%, and 20% of the total BOD load. Overall, the results showed that no significant changes in the behavior of biological processes. The IAS unit presented average BOD removal efficiencies of above 88%, 87% and 80% for the three leachate load contributions of 5%, 10% and 20% studied. The CAS unit presented lower average efficiency with a 5% leachate contribution (64%), but displayed a similar performance to the IAS unit in the other phases (82% and 80%); similar quantitative aspects were observed for both treatment processes with regards to biomass composition analysis. The kinetic coefficients related to heterotrophic metabolism did not indicate negative effects on treatment efficiency as a result of the increase in leachate addition, with values of 2.8; 2.8 and 2.7 d-1 obtained respectively for each phase with the CAS unit, and 2.0; 1.5 and 1.6 d-1 with the IAS unit, representing similar values to those found in the literature (1.5 a 5.0 d-1). The results reinforced the conclusion that the leachate load introduced did not cause inhibition or significant alterations to heterotrophic metabolism, and, therefore, to the removal of organic matter.

Assuntos