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The study aims to determine SARS‐CoV‐2 RNA in sewage of Cancun wastewater treatment plants, the main touristic destination of Mexico, and to estimate the infected persons during the sampling period. SARS‐CoV‐2 RNA traces were detected in the inlet of the five plants during almost all the sampling months. However, there is no presence of SARS‐CoV‐2 RNA traces in the effluent of the five WWTPs during the study period. ANOVA analysis showed differences in the concentrations of RNA traces of SARS‐CoV‐2 between the sample dates, but no differences were found from one WWTP to another. Estimated infected individuals by Markov chain Monte Carlo simulation are higher (between 77% and 91%) than the cases reported by the health authority. Wastewater monitoring and the estimation of infected individuals are a helpful tool, because estimation provides early warning signs on how broadly SARS‐CoV‐2 is circulating in the city, and led to the authorities to take measures wisely. Practitioner Points: There is no presence of SARS‐CoV‐2 RNA traces in the effluent of the facilities, suggesting the effectiveness of treatment.Surveillance of viral RNA concentrations at treatment plants revealed presence in the influent of five plantsEstimated infected individuals by MCMC simulation are higher than cases reported by health authorityEnvironmental surveillance approach in wastewater influent is helpful to identify the clusters and to take informed decisions [ABSTRACT FROM AUTHOR]

The development of sensitive and affordable testing devices for infectious diseases is essential to preserve public health, especially in pandemic scenarios. In this work, we have developed an attractive analytical method to monitor products of genetic amplification, particularly the loop-mediated isothermal amplification reaction (RT-LAMP). The method is based on electrochemical impedance measurements and the distribution of relaxation times model, to provide the so-called time-constant-domain spectroscopy (TCDS). The proposed method is tested for the SARS-CoV-2 genome, since it has been of worldwide interest due to the COVID-19 pandemic. Particularly, once the method is calibrated, its performance is demonstrated using real wastewater samples. Moreover, we propose a simple classification algorithm based on TCDS data to discriminate among positive and negative samples. Results show how a TCDS-based method provides an alternative mechanism for label-free and automated assays, exhibiting robustness and specificity for genetic detection. [ABSTRACT FROM AUTHOR]

BACKGROUND: Fermentative hydrogen production has an inherent limitation caused by hydrogen‐consuming metabolic pathways such as homoacetogenesis related to high hydrogen partial pressures. In this study, a strategy based on recirculating the headspace gas was applied to increase the hydrogen release from the liquid to the gas phase in an upflow anaerobic sludge blanket(UASB) reactor fed with winery effluents. The influence of the gas upflow recirculation velocity on hydrogen production, hydrogen consumption by homoacetogenesis, and microbial community structure was evaluated. RESULTS: Under the control condition (only liquid recirculation), the hydrogen productivity was as much as 22 mL H2 L−1 h−1. Conversely, the hydrogen productivity increased up to 62 mL H2 L−1 h−1 when the reactor was operated with an upflow gas recirculation velocity of 28.6 m d−1. The increase in mass transfer, due to the gas recirculation, produces a decrease (up to 70%) in the hydrogen consumption rate associated with homoacetogenesis. High‐throughput 16s rDNA sequencing characterization showed that the gas recirculation strategy promoted the development of hydrogen‐producing microorganisms related to Megasphaera elsdenii and decreased the abundance of hydrogen‐consuming bacteria related to Clostridium carboxidivorans and C. ljungdahlii. CONCLUSION: The results indicated that headspace recirculation at gas upflow velocities higher than 17.8 m d−1 increased the hydrogen production rate concomitantly with the reduction of both the homoacetogenic activity and the abundance of H2‐consuming bacteria. The study demonstrated that headspace recirculation could be a promising way to control homoacetogenesis, and therefore, to increase the biohydrogen productivity from complex substrates such as winery effluents. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Pretreatments to break down complex biopolymers in microalgae cells are a key process in the production of gaseous biofuels (methane and hydrogen) from such biomass. Biological pretreatment implies cell degradation by purified enzymes; enzymatic cocktails or by microorganisms with enzymatic activity capable of hydrolyzing the microalgae cell wall. This review presents relevant results using those methods that are less energy intensive and, in some cases, more specific than other strategies, such as chemical and physical pretreatments. Enzymatic pretreatments are specific and efficient, with cellulase, hemicellulase, pectinase, protease and amylase being the most explored enzymes. For biomass pretreatment, enzymatic cocktails have been more effective than single enzymes, as it is more feasible to obtain enzymatic extracts of one or more hydrolytic microorganisms than their purified enzymes. The potential use of hydrolytic cultures for cell disruption to breakdown complex biopolymers has been demonstrated. Their use is less specific than that of enzymatic extracts, but more cost-effective. Pure cultures of hydrolytic bacteria, most of which have carbohydrase activities, have increased the biofuel conversion efficiency from microalgae and from bacterial consortia. The use of natural microbial consortia with hydrolytic activities, such as ruminal microorganisms, represents a potential pretreatment for microalgae. In this review, common hydrolytic activities are highlighted and compared, and the use of ruminal microorganisms as a cell disruption strategy is discussed. Understanding the operational conditions applied to natural consortia, such as ruminal microorganisms, will favor a suitable system for microalgae cell disruption that may increase the biological hydrogen and methane recovery from microalgae. [ABSTRACT FROM AUTHOR]

There are several parameters that affect the hydrogen (H 2 ) production when using organic solid waste in a discontinuous process, such as the hydraulic retention time (HRT). To optimize the process, it is necessary to determine the HRT such that the H 2 production is maximized. The objective of this study is to evaluate the effect of different HRTs on the hydrogen production in an anaerobic sequencing batch reactor (ASBR) using food waste as the substrate. The microbial community was analyzed and correlated with the reactor performance. The results showed that the highest percentage of H 2 in biogas, maximum volumetric H 2 production, and maximum H 2 production rate was obtained with an HRT of 24 h. The percentage of H 2 in biogas varied from 22 to 53%, which depended on the HRT. Acetic acid was the main volatile fatty acid obtained. The highest propionic acid production was observed with an HRT of 6 h, which was related to a decrease in H 2 generation, where a low diversity and low evenness were obtained compared with those of the reactor samples obtained from different HRTs. The genus Megasphaera was found to be the dominant genus in the microbial community. [ABSTRACT FROM AUTHOR]

Biofilms on food-contact surfaces can lead to recurrent contamination. This work aimed to study the biofilm formation process on stainless steel plates used in the dairy industry: 304 surface finish 2B and electropolished; and the effect of a cleaning and disinfection process using alkaline (AEW) and neutral (NEW) electrolyzed water. Milk fouling during heat processing can lead to type A or B deposits, which were analyzed for composition, surface energy, thickness, and roughness, while the role of raw milk microbiota on biofilm development was investigated. Bacteria, yeasts, and lactic acid bacteria were detected using EUB-338, PF2, and Str-493 probes, respectively, whereas Lis-637 probe detected Listeria sp. The genetic complexity and diversity of biofilms varied according to biofilm maturation day, as evaluated by 16S rRNA gene sequence, denaturing gradient gel electrophoresis, and fluorescence in situ hybridization microscopy. From analysis of the experimental designs, a cleaning stage of 50 mg/L NaOH of AEW at 30 °C for 10 min, followed by disinfection using 50 mg/L total available chlorine of NEW at 20 °C for 5 min is a sustainable alternative process to prevent biofilm formation. Fluorescence microscopy was used to visualize the effectiveness of this process. [ABSTRACT FROM AUTHOR]

In the present work, the effect of anthraquinone-2-sulfonate (AQS) and its reduced form anthrahydroxyquinone-2-sulfonate (AH 2 QS), and different pH values were evaluated during a dark fermentation process using heat-treated anaerobic granular sludge for hydrogen production. The highest maximum hydrogen production (1.99 mmol) was obtained by adding the reduced electron shuttling compound (AH 2 QS) at pH 6. This experimental condition also reflected the highest substrate consumption efficiency and the lowest lag phase in relation to the AQS and the control (only sludge). In contrast, the lag phase and maximum hydrogen production were not impacted by AH 2 QS addition at initial pH of 6.4 and 7.8. Regardless of the initial pH value, the hydrogen production rate was increased after the addition of the electron shuttling compounds, which could be attributable to the performance of either the oxidized and reduced form of the electron shuttling compound. These findings demonstrate the feasibility of AH 2 QS addition during dark fermentation at pH 6.4 for improving the hydrogen production rate. Exoelectrogenic microorganisms identified in the inoculum could be responsible to improve the dark fermentation process in assays with electron shuttling compounds. [ABSTRACT FROM AUTHOR]

This work proves the feasibility of employing regular secondary activated sludge for the enrichment of a microbial community able to perform the anaerobic oxidation of methane coupled to nitrate reduction (N-AOM). After 96 days of activated sludge enrichment, a clear N-AOM activity was observed in the resulting microbial community. The methane removal potential of the enriched N-AOM culture was then studied in a stirred tank reactor (STR) operated in continuous mode for methane supply and semi-continuous mode for the liquid phase. The effect of applying nitrate loads of ∼22, 44, 66, and 88 g NO 3 − m−3 h−1 on (i) STR methane and nitrate removal performance, (ii) N 2 O emission, and (iii) microbial composition was investigated. Methane elimination capacities from 21 ± 13.3 to 55 ± 12 g CH 4 m−3 h−1 were recorded, coupled to nitrate removal rates ranging from 6 ± 3.2 to 43 ± 14.9 g NO 3 − m−3 h−1. N 2 O production was not detected under the three nitrate loading rates applied for the assessment of potential N 2 O emission in the continuous N-AOM process (i.e. ∼22–66 g NO−3 m−3 h−1). The lack of N 2 O emissions during the process was attributed to the N 2 O reducing capacity of the bacterial taxa identified and the rigorous control of dissolved O 2 and pH implemented (dissolved O 2 values ≤ 0.07 g m−3 and pH of 7.6 ± 0.4). Microbial characterization showed that the N-AOM process was performed in absence of putative N-AOM archaea and bacteria (ANME-2d, M. oxyfera). Instead, microbial activity was driven by methane-oxidizing bacteria and denitrifying bacteria (Bacteroidetes, α-, and γ-proteobacteria). [Display omitted] • Continuous N-AOM was successfully implemented from activated sludge. • N 2 O was not detected at nitrate loading rates of 22–66 gNO 3 - m−3 h−1. • A maximum CH 4 elimination capacity of ∼55 g m−3 h−1 was recorded. • M. nitroreducens (ANME-2d) and M. oxyfera were absent. [ABSTRACT FROM AUTHOR]

The heat-shock pretreatment (HST) is a useful method to select for H 2 -producing inocula when soluble substrates are employed. However, the HST has proven to have negative effects on the H 2 production performance from lignocellulosic substrates. We hypothesize that the negative effect of HST on H 2 production from lignocellulosic substrates is due to the loss of species involved in cellulose solubilization. In the present study, we tested this hypothesis by applying a heat-shock pretreatment (105 °C/24 h) on the microbial community for producing hydrogen from microcrystalline cellulose. Specifically, we compared a microbial community treated with 2-bromoethanesulfonate (BES-treated control) versus a heat-shock pretreated microbial community. For both experimental treatments, we determined the major fermentation products (hydrogen, acetic, butyric, propionic, and isovaleric acids), as well as the diversity of bacteria and fungi using Illumina MiSeq of amplicons in five sampling points. We found that HST immediately reduced alpha diversity of microbial communities, being fungi more affected than bacteria. We also found that the bacterial reduction in Comamonas , Ureibacillus , and Aneurinibacillus was related to a low hydrogen production in the heat-shock pretreated community. Strictly anaerobic fungi such as Orpinomyces , Cyllamyces , and Neocallimastix , which are recognized by their role in solubilization of fibrous materials, were unable to survive the HST. The reconstructed bacterial network predicted positive interactions between cellulase-producing and hydrogen-producing families. We conclude that the HST did not promote the high microbial diversity required for hydrogen production from cellulose. • Two inoculum pretreatments were compared for H 2 production from crystalline cellulose. • Heat-shock treatment caused a lower diversity and productivity than chemical treatment. • The poor hydrogen performance was explained by the loss of diversity. • Positive bacterial interactions were only predicted for the chemical treated community. • The heat-shock treatment was inefficient to select a productive community. [ABSTRACT FROM AUTHOR]

• Four pretreatments were compared in terms of solubilization and methane production. • Dilute acid pretreatment reached the highest solubilization of organic matter. • Hydrolyzates differentiate only in terms of lag phase and the methane production rate. • Most hydrolyzates reached the same biochemical methane potential of 219 mL CH 4 /g COD. Agave bagasse is a lignocellulosic agroindustrial waste suitable for biofuel production. This study aimed to compare biological, enzymatic, chemical, and hydrothermal pretreatments applied to Agave bagasse in terms of solubilization of carbohydrates (CHO) and chemical oxygen demand (COD), as well as the biochemical methane potential (BMP) from hydrolyzates. Most pretreatments behave similarly, with an average yield of 0.16 ± 0.02 g COD /g, only the chemical pretreatment overcame this yield by a factor of 2.6 with a CHO/COD ratio of 0.95. The concentrations of inhibitors – furfural, hydroxymethylfurfural, and phenols – were higher in the chemical hydrolyzates than in the biological and enzymatic hydrolyzates. BMP from most hydrolyzates was the same, on average 219 ± 15 mL/g CODin , hydrolyzates differentiate only in terms of lag phase and the methane production rates. [ABSTRACT FROM AUTHOR]

Currently, SARS-CoV-2 has been detected in the influent of wastewater treatment plants (WWTP), pumping stations, manholes, sewer networks and sludge of WWTP and facilities of countries as France, Spain, Italy, Netherlands, United States, Australia, Ecuador, Brazil and Japan. Although this virus has been detected in the wastewater streams, there is no robust method for its detection and quantification in wastewater. This review compiled and analyzed the virus concentration approaches applied to detect the SARS-CoV-2, besides to provide insights about the methodology for viral concentration, limit of detection, occurrence, persistence, and perspectives post-COVID-19 related with the implications of the virus presence in wastewater. The SARS-COV-2 detection in wastewater has been related to virus concentration methods, which present different recovery rates of the virus. The most used viral concentration methods have been the polyethylene glycol (PEG) for precipitation of viral material and the ultrafiltration at molecular weight level. After viral concentration, the detection and quantification of SARS-COV-2 in wastewater are mainly via quantitative reverse transcription polymerase chain reaction (RT-qPCR), which is the clinical assay adapted for environmental purposes. Although in some experiments the positive control during RT-qPCR is running a surrogated virus (e.g., Mengovirus or Dengue virus), RT-qPCR or reverse transcription droplet digital PCR (RT-ddPCR) targeting the gene encoding nucleocapsid (N1, N2 and N3) of SARS-COV-2 are highly recommended to calculate the limit of detection in wastewater samples. Current results suggest that a rigorous methodology to elucidate the positive cases in a region from genomic copies in wastewater is needed., Competing Interests: The authors report no declarations of interest., (© 2021 Elsevier Ltd. All rights reserved.)

The SARS-CoV-2 virus causing COVID-19 is spread in sewage by the stool of infected individuals, and viral material in sewage can be quantified using molecular tools. This study aimed to monitor the presence of SARS-CoV-2 RNA in sewage in Mexico based on RdRP, S, and N gene analysis. The influent, effluent, and activated sludge from two domestic wastewater treatment plants (WWTP) were evaluated from the early stage of the epidemic to July 2020. Additionally, sampling points in sewer systems were examined, comparing two different RNA-concentration methods: centrifugal ultrafiltration and adsorption-based methods. The adsorption method resulted in RNA titration that was two orders of magnitude higher than with ultrafiltration (up to 3.38 log 10 copies RdRP gene/mL of sewage). The surveillance of SARS-CoV-2 RNA in the influent of two WWTP correlated with the cumulative COVID-19 cases in Queretaro city. The higher RNA level in secondary sludge compared to influent suggests that viral RNA becomes concentrated in activated sludge. This result supports SARS-CoV-2 RNA removal in WWTP, where all effluent samples were negative for virus quantification. This work proves that wastewater-based epidemiology is a very valuable tool in developing countries where diagnostic tests for COVID-19 are limited., Competing Interests: The authors declare no conflict of interest to disclose., (© 2020 Elsevier Ltd. All rights reserved.)

Biohydrogen production potential (BHP) depends on several factors like inoculum source, substrate, pH, among many others. Batch assays are the most common strategy to evaluate such parameters, where the comparison is a challenging task due to the different procedures used. The present method introduces the first internationally validated protocol, evaluated by 8 independent laboratories from 5 different countries, to assess the biohydrogen potential. As quality criteria, a coefficient of variation of the cumulative hydrogen production ( H max ) was defined to be <15 %. Two options to run BHP batch tests were proposed; a manual protocol with periodic measurements of biogas production, needing conventional laboratory materials and analytical equipment for biogas characterization; and an automatic protocol, which is run in a device developed for online measurements of low biogas production. The detailed procedures for both protocol options are presented, as well as data validating them. The validation showed acceptable repeatability and reproducibility, measured as intra- and inter-laboratory coefficient of variation, which can be reduced up to 9 %., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2019 The Authors.)