Diversity and dynamics of bacterial communities in the drinking water distribution network of a mid-sized city in Brazil.

This study assessed the bacterial community composition of a drinking water system (DWS) serving a mid-sized city (120,000 inhabitants) in Brazil. Water samples, including raw and treated water, were collected at seven points throughout the DWS. DNA was extracted and analysed using high-throughput sequencing (Ion Torrent). Free chlorine and turbidity were measured in situ. Results showed that the highest relative abundance of 16S rRNA genes was from phyla Proteobacteria, followed by Bacteroidetes and Actinobacteria. The next most abundant phylum was Cyanobacteria, represented by Arthronema, Calothrix, and Synechococcus. An interesting observation was that the DNA-based analysis suggested a bacterial community change in the distribution network, with treated reservoir water being very different from the network samples. This suggests active microbiology within the distribution network and a tendency for bacterial diversity to decrease after chlorine disinfection but increase after pipeline distribution. In raw water, a predominance of Proteobacteria was observed with reduced Cyanobacteria, showing a negative correlation. In treated water, Proteobacteria were negatively correlated with Bacteroidetes. Finally, 16S rRNA genes from Firmicutes (especially Staphylococcus) had a high abundance in the chlorinated water, which may indicate the phylum's resistance to chlorine residuals. Opportunistic pathogens, e.g., Mycobacteria, Legionella, and Staphylococcus, were also observed.

Reduction and liquid-solid partitioning of SARS-CoV-2 and adenovirus throughout the different stages of a pilot-scale wastewater treatment plant.

Investigating waterborne viruses is of great importance to minimizing risks to public health. Viruses tend to adsorb to sludge particles from wastewater processes by electrostatic and hydrophobic interactions between virus, aquatic matrix, and particle surface. Sludge is often re-used in agriculture; therefore, its evaluation is also of great interest to public health. In the present study, a pilot scale system treating real domestic wastewater from a large city in Brazil was used to evaluate the removal, the overall reduction, and liquid-solid partitioning of human adenovirus (HAdV), the novel coronavirus (SARS-CoV-2) and fecal indicators (F-specific coliphages and E. coli). The system consists of a high-rate algal pond (HRAP) post-treating the effluent of an upflow anaerobic sludge blanket (UASB) reactor. Samples were collected from the influent and effluent of each unit, as well as from the sludge of the UASB and from the microalgae biomass in the HRAP. Pathogens and indicators were quantified by quantitative polymerase chain reaction (qPCR) (for HAdV), qPCR with reverse transcription (RTqPCR) (for SARS-CoV-2), the double agar plaque assay (for coliphages), and the most probable number (MPN) method (for E. coli). The removal and overall reduction of HAdV and SARS-CoV-2 was greater than 1-log10. Almost 60% of remaining SARS-CoV-2 RNA and more than 70% of remaining HAdV DNA left the system in the sludge, demonstrating that both viruses may have affinity for solids. Coliphages showed a much lower affinity to solids, with only 3.7% leaving the system in the sludge. The system performed well in terms of the removal of organic matter and ammoniacal nitrogen, however tertiary treatment would be necessary to provide further pathogen reduction, if the effluent is to be reused in agriculture. To our knowledge, this is the first study that evaluated the reduction and partitioning of SARS-CoV-2 and HAdV through the complete cycle of a wastewater treatment system consisting of a UASB reactor followed by HRAPs.

Effect of digestate loading rates on microalgae-based treatment under low LED light intensity.

Low red-LED irradiances are an attractive alternative for enhancing microalgae photobioreactors treating digestate due to their potential contribution in decreasing area footprints with low energy consumptions. However, more information is required regarding the influence of digestate load on treatment performance and biomass valorisation when low-intensity red-LEDs are applied. Thus, this study assessed microalgae-based photobioreactors treating food waste digestate under different concentrations (5%, 25%, 50%, and 75%, v/v) at low red-LED irradiance (15 µmol·m-2·s-1). The removal efficiencies of soluble chemical oxygen demand (sCOD) at the end of the experiment ranged from 45% to 75% when treating influent loads between 5.3 and 79.1 g sCOD·m-3·d-1 (5% and 75%-digestate), respectively. Total ammonia nitrogen (TAN) was applied in loading rates between 3.2 and 48.5 g TAN·m-3·d-1 (5% and 75%, respectively) and removed with maximum efficiencies of 90%-100% in all trials. Nitrification-denitrification was proportionally more relevant when treating 5%-digestate, whereas volatilisation was the primary process in 25%, 50% and 75% concentrations. Microalgae presented adequate yields in all treatments, except in 75%-digestate, likely due to the blocking of light by the high solids concentrations. The assessment of the microalgae community and chlorophyll-a and carotenoids suggested that chlorophytes, mainly Dictyosphaerium pulchellum and Scenedesmus sp. grew autotrophically, whereas cyanobacteria Pseudanabaena sp. grew mixotrophically. Moreover, the sustainability of red LED lighting applications can be increased by anaerobic digestion or agricultural valorisation of the biomass, enabled by its high N and P contents. Low-intensity red-LEDs may have promissory applications in the treatment of high-strength wastewaters.

Monitoramento do esgoto como ferramenta de vigilância epidemiológica para controle da COVID-19: estudo de caso na cidade de Belo Horizonte / Sewage monitoring as a surveillance epidemiological tool for COVID-19 control: a case study in the city of Belo Horizonte

RESUMO A recente detecção de material genético (RNA) do novo coronavírus em amostras de fezes e no esgoto aponta para a possibilidade de se identificar a circulação do vírus e até mesmo estimar o número de pessoas infectadas em determinada região pelo monitoramento sistemático do esgoto, configurando-se em importante ferramenta epidemiológica de testagem massiva indireta, incluindo portadores sintomáticos e assintomáticos. Nesse sentido, concebeu-se um projeto para a detecção e a quantificação do novo coronavírus em amostras de esgoto coletadas em 15 sub-bacias de esgotamento sanitário dos ribeirões Arrudas e Onça, visando entender a dinâmica de circulação e a prevalência do vírus nas regiões investigadas. Tais sub-bacias esgotam os efluentes gerados por uma população da ordem de 1,5 milhão de pessoas no município de Belo Horizonte e parte de Contagem. O plano de amostragem contemplou 17 pontos (15 sub-bacias + afluente às 2 estações de tratamento de esgoto) de monitoramento semanal, com coletas compostas durante todo o período da manhã. A detecção e a quantificação do RNA viral efetuaram-se em laboratório por meio de ensaios de RT-qPCR. Os resultados obtidos em quatro semanas de monitoramento (semanas epidemiológicas 21 a 24) mostraram um incremento da ocorrência do vírus, atingindo 100% das regiões investigadas na semana epidemiológica 24. A estimativa da população infectada pelo novo coronavírus pelo monitoramento do esgoto em Belo Horizonte apresentou tendência de crescimento exponencial, sendo até 20 vezes maior do que o número de casos confirmados acumulados. Quanto à circulação do vírus, as concentrações do RNA viral têm se mostrado bastante variáveis nas regiões monitoradas, com maiores porcentagens de população infectada estimada ao norte e nordeste da capital mineira.

ABSTRACT The recent detection of SARS-CoV-2 RNA in stool and sewage samples highlights the possibility of mapping the circulation of the virus and even estimating the number of infected people through the systematic monitoring of sewage in a specific region. Therefore, this is an important epidemiological tool for large-scale indirect testing, including symptomatic and asymptomatic carriers. This project was conceived for the detection and quantification of the SARS-CoV-2 in sewage samples collected in 15 watersheds of the Arrudas and Onça streams, aiming to understand the dynamics of spread and the prevalence of the virus in these regions/watersheds. These sub-basins exhaust the effluents generated by a population of approximately 1.5 million people in the municipality of Belo Horizonte and part of Contagem. Weekly composite samples were collected during the morning periods in seventeen monitoring points (15 water sheds + influent to 2 sewage treatment plants). RNA detection and quantification were performed in the laboratory using RT-qPCR. The results obtained in four weeks of monitoring (epidemiological weeks 21 to 24) showed an increase in the occurrence of the virus, reaching 100% of the monitored regions investigated in epidemiological week 24. The infected population, estimated by sewage monitoring in Belo Horizonte, showed exponential growth, being up to 20 times higher than those of accumulated confirmed cases. As for the dynamics of virus spread, RNA concentrations have shown to be quite variable in the monitored regions with higher percentages of the estimated infected population in the northern and north-eastern portions of Belo Horizonte.

Planning for achieving low carbon and integrated resources recovery from sewage treatment plants in Minas Gerais, Brazil.

There is an enormous deficit in sanitation infrastructure in most Brazilian cities. To tackle this challenge, it is crucial to conceive the new sanitation infrastructure based on sustainability principles, including an integrated approach for the management of the liquid, solid and gaseous phases. This study aimed at developing sustainable sewage treatment flowsheets for different scales and regional scenarios in the state of Minas Gerais. Two watersheds were chosen as study areas, due to their remarkable regional importance and socioeconomic and environmental diversity, i.e. Rio das Velhas and Jequitaí-Pacuí. Currently available processes for sewage treatment and resources recovery were assessed based on: literature review and benchmarking of operational practices, experiences reported by sanitation companies, techno-economic feasibility of resource recovery and carbon footprint assessment of anaerobic-based technologies. Social acceptance was also considered. A total of 15 sustainable flowsheets were proposed, comprising passive/natural systems (stabilization ponds, constructed wetlands and controlled land application), anaerobic process combined with natural systems (UASB reactors followed by controlled land application, constructed wetlands or polishing ponds) and compact anaerobic/aerobic systems (UASB reactors followed by activated sludge or trickling filters). Processes selected for small-scale sewage treatment plants (STPs) (people-equivalent - PE < 10,000 inhab.) intended to be integrated into local communities and economic activities. Large-scale STPs (especially those with PE > 100,000 inhab.) were conceived as industries, where a wide range of resources (e.g. sand for non-structural concrete, biogas for electricity, sludge for thermal energy) could be recovered from the influent sewage. Results obtained from the current study could serve as support for decision-making on the planning and implementation of new sustainable sanitation solutions in the state of Minas Gerais and possibly in other regions of Brazil and other developing countries.

Treatment of food waste digestate using microalgae-based systems with low-intensity light-emitting diodes.

Anaerobic digestion of food wastes coupled with digestate post-treatment using microalgae-based systems could recover large amounts of energy and nutrients worldwide. However, the development of full-scale implementations requires overcoming microalgae inhibition by high ammonia concentrations and low light transmittances affecting photosynthesis. This study evaluated the potential of microalgae-based reactors supplied with red light-emitting diodes (LEDs) at low intensity (660 nm and 15 µmol·m-2·s-1) to treat food waste digestate. LED reactors were compared with control reactors exposed to solar radiation. From a range of species in the inoculum, Chlorella vulgaris showed high adaptation to both lighting regimes and digestate environmental conditions, characterized by a C:N:P ratio of 74:74:1. Removal efficiencies for control and LED reactors were 84.0% and 95.8% for soluble chemical oxygen demand (COD) and 89.4% and 53.0% for ammonia, respectively. Approximately 50% of ammonia in control reactor and 15% in LED reactor was lost from the systems, whereas 17% and 36% of ammonia was transformed to organic nitrogen in control and LED reactors, respectively. Low-intensity LEDs maintained microalgae growth in levels similar to solar radiation and supported efficient digestate treatment, showing a potential for further application in optimization of full scale reactors at a relatively low energy cost.

Dinâmica de protozoários patogênicos e cianobactérias em um reservatório de abastecimento público de água no sudeste do Brasil / Dinamic of pathogenic protozoa and cyanobacteria in a reservoir used for water supply in southeastern Brazil

RESUMO O presente estudo foi baseado no monitoramento de um reservatório tropical (Vargem das Flores) utilizado para o abastecimento público de água de sete cidades da região metropolitana de Belo Horizonte, Minas Gerais. O reservatório foi monitorado durante quatro anos: período inicial (de 2004 a 2007) para células de cianobactérias e parâmetros físico-químicos e, subsequentemente (2007 e 2008), para oocistos de Cryptosporidium spp. e cistos de Giardia spp. em quatro estações de amostragem. Também foram avaliadas as concentrações de Escherichia coli de 2007 a 2008, o que permitiu a caracterização de cada ponto de amostragem de acordo com a legislação do Conselho Nacional do Meio Ambiente (CONAMA) nº 274/2000. Os resultados indicaram concentrações de (oo)cistos de Cryptosporidium spp. e Giardia spp. variando de 0 a 0,8 (oo)cistos.L-1, e as mais elevadas concentrações de células de cianobactérias, de 0,0 a 4,5 x 105 cels.mL-1, apontando assim para potencial risco à saúde humana caso a água do reservatório seja consumida sem tramento. As cianobactérias não foram encontradas durante a estação seca. O grupo retornou rapidamente após a desestratificação. A estação chuvosa foi caracterizada pela elevada ocorrência de cianobactérias com a predominância da espécie picoplanctônica (Aphanocapsa sp.), sobre Microcystis spp. previamente detectada, e apresentou as maiores variações de oxigênio dissolvido, turbidez, fósforo total, ortofosfato, amônia, nitrito e nitrato. A mudança observada no grupo das cianobactérias (Aphanocapsa spp. sobre Microcystis spp.) pode ser um indicativo das alterações das características da água. De acordo com as concentrações de E. coli , as estações foram classificadas como próprias para recreação de contato primário, de acordo com a Resolução CONAMA nº 274/2000.

ABSTRACT The current study monitored the water quality of a tropical reservoir (Vargem das Flores) used to supply potable water to seven cities in the metropolitan area of Belo Horizonte, Minas Gerais, southeast Brazil. The reservoir was monitored for four years: initially (from 2004 to 2007) for cyanobacterial cells and physicochemical parameters and, subsequently (in 2007 and 2008), for Cryptosporidium spp. oocysts and Giardia spp. cysts in four sampling stations. The concentrations of Escherichia coli were also measured in 2007 and 2008, wich allowed the characterization of each sampling point according to the National Environment Council (CONAMA) no. 274/2000. Results indicated concentrations of Cryptosporidium spp. and Giardia spp. (oo)cysts ranging from 0 to 0.8 (oo)cysts.L-1, and higher concentrations of cyanobacteria cells, from 0.0 to 4.5 x 105 cells.mL-1, thus indicating potential risks to human health, if the water from the reservoir is not properly treated before consumption. The group of cyanobacteria was not found during the dry season, returning soon after destratification. The rainy season was characterized by a higher ocurrence of cyanobacteria and predominance of picoplanktonic species (Aphanocapsa spp.), over the Microcystis spp. previously found and presented the highest variations in dissolved oxygen, turbidity, total phosphorous, orthophosphate, ammonia, nitrite and nitrate. The change observed within the group of cyanobacteria (Aphanocapsa spp. over Microcystis spp.) may be indicative of changing characteristics in the water source. All the sampling points were classified as adequate for primary contact recreation, given the E. coli concentrations, according to the CONAMA Resolution no. 274/2000.