Stratified microbial structure and activity in sulfide- and methane- producing anaerobic sewer biofilms

Simultaneous production of sulfide and methane by anaerobic sewer biofilms has recently been observed, suggesting that sulfate-reducing bacteria (SRB) and methanogenic archaea (MA), microorganisms known to compete for the same substrates, can coexist in this environment. This study investigated the community structures and activities of SRB and MA in anaerobic sewer biofilms (average thickness of 800 mu m) using a combination of microelectrode measurements, molecular techniques, and mathematical modeling. It was seen that sulfide was mainly produced in the outer layer of the biofilm, between the depths of 0 and 300 mu m, which is in good agreement with the distribution of SRB population as revealed by cryosection-fluorescence in situ hybridization (FISH). SRB had a higher relative abundance of 20% on the surface layer, which decreased gradually to below 3% at a depth of 400 mu m. In contrast, MA mainly inhabited the inner layer of the biofilm. Their relative abundances increased from 10% to 75% at depths of 200 mu m and 700 mu m, respectively, from the biofilm surface layer. High-throughput pyrosequencing of 16S rRNA amplicons showed that SRB in the biofilm were mainly affiliated with five genera, Desulfobulbus, Desulfomicrobium, Desulfovibrio, Desulfatiferula, and Desulforegula, while about 90% of the MA population belonged to the genus Methanosaeta. The spatial organizations of SRB and MA revealed by pyrosequencing were consistent with the FISH results. A biofilm model was constructed to simulate the SRB and MA distributions in the anaerobic sewer biofilm. The good fit between model predictions and the experimental data indicate that the coexistence and spatial structure of SRB and MA in the biofilm resulted from the microbial types and their metabolic transformations and interactions with substrates

Growth status, curd yield and crop duration of late season cauliflower varieties

Cauliflower is an important winter season vegetable crop having year-round demand in Nepal. Due to longer crop duration in late winter season, there was a production of poor-quality curds and lower yield faced by the farmers in Terai region of Nepal. An experiment was conducted to identify the short duration late season varieties at Rampur, Chitwan Nepal during November 2016 to March, 2017. These varieties were Freedom, Titan, Ravella, Amazing, Artica, Bishop, Casper, Indam 9803 and NS 106 (introduced from USA, Europe and India), and Snow Mystique and Snowball 16 (introduced from Japan). The experiment was laid out in Randomized Complete Block Design (RCBD) with four replications. The highest plant height (71.9 cm) and canopy diameter (74.5 cm) at last harvest of cauliflower was mostly produced by Titan followed by NS 106, Snow Mystique, Bishop and Indam 9803. Similarly, significantly shorter period for final curd initiation of 65 days after transplanting was observed in Freedom and shorter period for final curd maturation of 77 days after transplanting was also recorded in Freedom than other varieties. Significantly, higher curd yield of 54.8 t/ha was produced by Bishop than other varieties. In conclusion, Bishop was the best hybrid variety while other suitable varieties were NS 106, Titan, Artica and Snow Mystique for better growth and higher curd yield in Chitwan condition. Similarly, Freedom was identified as short duration varieties which can minimize the negative effects in late winter season due to higher temperature

Phytochemistry, Biological Activities, and Chemical Profiling of Berberis asiatica

This study focused on chemical profiling and assessed the total phenolic and flavonoid content as well as the antioxidant and antibacterial effect of the medicinal plant Berberis asiatica. The results revealed that this plant has high concentrations of TPC (Total phenol content) and TFC (Total flavonoid content) of 37.686 ± 2.728 mg GAE/g and 115.568 ± 8.012 mg QE/g, respectively. The DPPH free radical scavenging assay demonstrated strong inhibition, with an IC50 of 205.7 ± 5.353 μg/mL, and also showed robust antibacterial properties against Staphylococcus aureus and Klebsiella pneumoniae with a zone of inhibition (ZOI) of 14 mm and 19 mm, respectively. The extract exhibited an excellent inhibitory potential against S. aureus, and K. pneumoniae with an MIC (Minimum inhibitory concentration) of 0.39 mg/mL, and 3.125 mg/mL respectively, indicating significant inhibitory action. Furthermore, the MBC (Minimum bactericidal concentration) for both S. aureus and K. pneumoniae was found to be 6.25 mg/mL, emphasizing the extract's consistent bactericidal effectiveness against these bacteria. These findings underscore the potential utility of the methanolic extract of Berberis asiatica as a natural antibacterial agent. GC-MS analysis of hexane fraction indicates the plant is rich in secondary metabolites, specifically 2,2-dimethyl-3-pentanol, 2-methyl-2-pentanol, 2,5-dimethyl-4-hydroxy-3-hexanone, 3-hexanol, 4-methyl-2-pentanol are identified. Overall, this study highlights the importance of plant-based natural products as potential sources of antioxidants and antibacterial agents that contributes to the future drug development process

Sampling considerations and assessment of Exetainer usage for measuring dissolved and gaseous methane and nitrous oxide in aquatic systems

Pre-evacuated Exetainers are commonly used as measurement vials for the determination of methane (CH4) and nitrous oxide (N2O) concentrations in liquid and gaseous samples from aquatic environments. The impact of residual air in these Exetainers on measurement accuracy is assessed. Residual air pressure in commercially available, pre-evacuated Exetainers varied between 0.071 +/- 0.008 atm and 0.180 +/- 0.031 atm in examined batches. This background contamination can lead to large errors when determining dissolved and gaseous CH4 and N2O concentrations particularly at low concentrations. A method for Exetainer pretreatment is suggested and verified, to reduce the residual CH4 and N2O. Vials are flushed (needle 30 G 3 0.5 '', 0.3 mm) with nitrogen gas (N-2) for 5 min, which reduces the background CH4 and N2O concentrations to 0.092 +/- 0.008 ppm and 0.016 +/- 0.001 ppm, respectively, approximately 3-4% of their respective concentrations in air. To avoid an alteration of sample concentration by variable residual gas levels left during a pre-evacuation step, liquid and gaseous samples are injected into the N-2 filled Exetainers. For gaseous samples where large volumes of gas are available, Exetainers can alternatively be flushed with 100 mL of sampling gas. For gaseous samples, measured CH4 and N2O concentrations of standard gases were statistically identical to their known concentrations. For liquid samples, measured CH4 and N2O concentrations of liquid standard dilution series showed strong linear correlations with theoretically calculated concentrations (slope CH4: 1.04, slope N2O: 1.12). Sample concentrations remained constant over a minimum storage period of 6 weeks

An efficient method for measuring dissolved VOSCs in wastewater using GC-SCD with static headspace technique

Volatile organic sulfur compounds (VOSCs) are important sources of unpleasant odor in wastewater systems. However, the study of VOSCs is usually hindered by their complicated measurement method and highly reactive nature. In this work, a static headspace method utilising gas chromatography (GC) with a sulfur chemiluminescence detector (SCD) was developed to quantitatively analyze VOSCs in wastewater matrices. The method has low detection limits and requires no pre-concentration treatment. Three typical VOSCs, namely methanethiol (MT), dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), were chosen as examples for this study. The calibration curves of all three compounds covering a wide range from 0.5 ppb to 500 ppb showed good linearity (R-2 > 0.999). The method detection limits (MDL) were 0.08, 0.12 and 0.21 ppb for MT, DMS and DMDS, respectively. The reproducibility (relative standard deviation) was approximately 2%. The recovery ratio of MT, DMS and DMDS in spiked wastewater samples were 83 +/- 4%, 103 +/- 4% and 102 +/- 3%, respectively. Sample preservation tests showed that VOSCs in wastewater samples could be preserved in vials without headspace under acidified conditions (pH similar to 1.1) for at least 24 h without significant changes

Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Background: In an era of shifting global agendas and expanded emphasis on non-communicable diseases and injuries along with communicable diseases, sound evidence on trends by cause at the national level is essential. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) provides a systematic scientific assessment of published, publicly available, and contributed data on incidence, prevalence, and mortality for a mutually exclusive and collectively exhaustive list of diseases and injuries. Methods: GBD estimates incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) due to 369 diseases and injuries, for two sexes, and for 204 countries and territories. Input data were extracted from censuses, household surveys, civil registration and vital statistics, disease registries, health service use, air pollution monitors, satellite imaging, disease notifications, and other sources. Cause-specific death rates and cause fractions were calculated using the Cause of Death Ensemble model and spatiotemporal Gaussian process regression. Cause-specific deaths were adjusted to match the total all-cause deaths calculated as part of the GBD population, fertility, and mortality estimates. Deaths were multiplied by standard life expectancy at each age to calculate YLLs. A Bayesian meta-regression modelling tool, DisMod-MR 2.1, was used to ensure consistency between incidence, prevalence, remission, excess mortality, and cause-specific mortality for most causes. Prevalence estimates were multiplied by disability weights for mutually exclusive sequelae of diseases and injuries to calculate YLDs. We considered results in the context of the Socio-demographic Index (SDI), a composite indicator of income per capita, years of schooling, and fertility rate in females younger than 25 years. Uncertainty intervals (UIs) were generated for every metric using the 25th and 975th ordered 1000 draw values of the posterior distribution. Findings: Global health has steadily improved over the past 30 years as measured by age-standardised DALY rates. After taking into account population growth and ageing, the absolute number of DALYs has remained stable. Since 2010, the pace of decline in global age-standardised DALY rates has accelerated in age groups younger than 50 years compared with the 1990–2010 time period, with the greatest annualised rate of decline occurring in the 0–9-year age group. Six infectious diseases were among the top ten causes of DALYs in children younger than 10 years in 2019: lower respiratory infections (ranked second), diarrhoeal diseases (third), malaria (fifth), meningitis (sixth), whooping cough (ninth), and sexually transmitted infections (which, in this age group, is fully accounted for by congenital syphilis; ranked tenth). In adolescents aged 10–24 years, three injury causes were among the top causes of DALYs: road injuries (ranked first), self-harm (third), and interpersonal violence (fifth). Five of the causes that were in the top ten for ages 10–24 years were also in the top ten in the 25–49-year age group: road injuries (ranked first), HIV/AIDS (second), low back pain (fourth), headache disorders (fifth), and depressive disorders (sixth). In 2019, ischaemic heart disease and stroke were the top-ranked causes of DALYs in both the 50–74-year and 75-years-and-older age groups. Since 1990, there has been a marked shift towards a greater proportion of burden due to YLDs from non-communicable diseases and injuries. In 2019, there were 11 countries where non-communicable disease and injury YLDs constituted more than half of all disease burden. Decreases in age-standardised DALY rates have accelerated over the past decade in countries at the lower end of the SDI range, while improvements have started to stagnate or even reverse in countries with higher SDI. Interpretation: As disability becomes an increasingly large component of disease burden and a larger component of health expenditure, greater research and developm nt investment is needed to identify new, more effective intervention strategies. With a rapidly ageing global population, the demands on health services to deal with disabling outcomes, which increase with age, will require policy makers to anticipate these changes. The mix of universal and more geographically specific influences on health reinforces the need for regular reporting on population health in detail and by underlying cause to help decision makers to identify success stories of disease control to emulate, as well as opportunities to improve. Funding: Bill & Melinda Gates Foundation. © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licens

High rate wastewater treatment using aerobic upflow sludge blanket (AUSB) with external oxygenation

A laboratory study was conducted using an aerobic upflow sludge blanket (AUSB) reactor to achieve high-rate biological treatment through maintenance of high biomass concentration (7-10 g VSS/L) together with high oxygen flux. Emphasis of the study was placed on evaluating the treatment performance under different organic loading rates, and different pressurizations/flow recirculations, which were employed to provide a needed oxygen flux. That is, the AUSB reactor was not aerated directly, but oxygenation was provided in an external chamber with or without flow recirculation, In most operation, the oxygenation was provided under pressure of up to 25 psig. Thus, the AUSB operation was also under pressure. The flow recirculation rate was varied from 400% to 1500% in order to ensure adequate oxygen supply. It was found that the AUSB process was able to handle a volumetric loading of as high as 3.83 kg TOC/m3-day (10 kg COD/m3-day) with the organic removal efficiency of 92% (equivalent to a volumetric removal rate of 3.58 kg TOC/m3-day). Out of this, about 20% of the organic removal was achieved in the oxygenation chamber. Despite the high upflow velocity through the reactor, the effluent suspended solids was mostly below 70 mg/L, which could be polished further for SS removal without using a conventional secondary clarifier. The AUSB sludge showed a high specific oxygen uptake rate (SOUR) of up to 180-250 mg O2/g VSS-hr, mainly due to a higher fraction of active biomass in the sludge flocs. Because of this, the biomass endogenous respiration rate was about 15 mg O2/g VSS-hr, which was also 3 to 4 times higher than that of the activated sludge flocs. The sludge yield in the AUSB system was around 0.3 to 0.4 g VSS/g COD removed without recirculation. However, with recirculation, the yield was only 0.09 to 0.18 g VSS/g COD removed. The low sludge yield was mainly caused by “enhanced auto-oxidation” of bio-solids in the oxygenation chamber, which had a very high DO and provided 10-30 minute HRT. Keywords: Aerobic upflow sludge blanket (AUSB); external oxygenation; pressurized reactor; flow recirculation; high-rate wastewater treatment; low sludge yiel

Process optimization of an aerobic upflow sludge blanket reactor system

Response of an aerobic upflow sludge blanket (AUSB) reactor system to the changes in operating conditions was investigated by varying two principle operating variables: the oxygenation pressure and the flow recirculation rate. The oxygenation pressure was varied between 0 and 25 psig (relative), while flow recirculation rates were between 1,300 and 600% correspondingly. The AUSB reactor system was able to handle a volumetric loading of as high as 3.8 kg total organic carbon (TOC)/m(3) day, with a removal efficiency of 92%. The rate of TOC removal by AUSB was highest at a pressure of 20 psig and it decreased when the pressure was increased to 25 psig and the flow recirculation rate was reduced to 600%. The TOC removal rate also decreased when the operating pressure was reduced to 0 and 15 psig, with corresponding increase in flow recirculation rates to 1,300 and 1,000%, respectively. Maintenance of a high dissolved oxygen level and a high flow recirculation rate was found to improve the substrate removal capacity of the AUSB system. The AUSB system was extremely effective in retaining the produced biomass despite a high upflow velocity and the overall sludge yield was only 0.24-0.32 g VSS/g TOC removed. However, the effluent TOC was relatively high due to the system's operation at a high organic loading

Effects of nitrate dosing on methanogenic activity in a sulfide-producing sewer biofilm reactor

Nitrate dosing is widely used by water industry to control hydrogen sulfide production in sewers. This study assessed the impact of nitrate addition on methane generation by sewer biofilms using a lab-scale rising main sewer reactor. It was found that methanogenesis could coexist with denitrification and sulfate reduction in sewers dosed with nitrate. However, methane production was substantially reduced by nitrate addition. Methanogenic rates remained below 10% of its baseline level, with 30 mg-N/L of nitrate dosing for each pump event. By calculating the substrate penetration depth in biofilms, it is suggested that methanogenesis may persist in deeper biofilms due to the limited penetration of nitrate and sulfate, and better penetration of soluble organic substrates. The control of methane and sulfide production was found to be determined by the nitrate penetration depth in biofilms and nitrate presence time in sewers, respectively. The presence of nitrous oxide after nitrate addition was transient, with a negligible discharge of nitrous oxide from the sewer reactor due to its further reduction by denitrifiers after nitrate depletion

Metformin and Troglitazone in the Treatment of Female Infertility Associated with Polycystic Ovarian Syndrome

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