Significance of Vivianite Precipitation on the Mobility of Iron in Anaerobically Digested Sludge

Anaerobic digestion requires a balanced availability of micro-nutrients with ideal growth conditions to reach optimal organic degradation and biogas production. Iron is the most abundant of the essential metals in an anaerobic digester and its mobility has a strong impact on microorganisms through its own bioavailability, but also through its influence on the bioavailability of other metals. Most previous research on iron mobility in anaerobic digestion has focused on sulfide as the controlling anion because digesters traditionally are sulfide rich and phosphate poor. However, chemical phosphorus removal (CPR) at wastewater treatment works (WWTW) can elevate phosphate concentrations in the digester 10-fold or more. The goal of this research was hence to examine the accepted wisdom of iron-sulfide dominance prevailing in all anaerobic digesters and by evaluating the potential for iron phosphate formation in municipal digesters treating CPR sludge. To fulfil this aim, iron compounds were identified experimentally from full-scale digesters at WWTW with CPR and the most likely iron species identified through modelling according to their thermodynamic probability of formation under the specific environmental conditions experienced in each anaerobic digester. Experimental and modelling data were then combined to identify the main chemical reactions controlling iron mobility in those anaerobic digesters.Results show that speciation of iron in the sampled anaerobic digesters was controlled by the solid phase through a primary reaction (sulfide precipitation to form pyrite and ferrous sulfide) and secondary reaction (phosphate precipitation to form vivianite). However, iron-sulfide precipitates represented only 10-30% of the total iron in the sampled digesters, while iron-phosphate precipitates represented more than 70%. The significance of the high quantity of vivianite in these digesters is that phosphate-rich anaerobic digesters will be more iron-mobile environments than sulfide-rich digesters, with iron being more readily exchanged between the solid and liquid phases during digestion, implying a higher level of bioavailability and the tendency to interact more readily with organic and inorganic counterparts

Trace Elements in Anaerobic Biotechnologies

The use of trace elements to promote biogas production features prominently on the agenda for many biogas-producing companies. However, the application of the technique is often characterized by trial-and-error methodology due to the ambiguous and scarce basic knowledge on the impact of trace elements in anaerobic biotechnologies under different process conditions. This book describes and defines the broad landscape in the research area of trace elements in anaerobic biotechnologies, from the level of advanced chemistry and single microbial cells, through to engineering and bioreactor technology and to the fate of trace elements in the environment. The book results from the EU COST Action on ‘The ecological roles of trace metals in anaerobic biotechnologies’. Trace elements in anaerobic biotechnologies is a critical, exceptionally complex and technical challenge. The challenging chemistry underpinning the availability of trace elements for biological uptake is very poorly understood, despite the importance of trace elements for successful anaerobic operations across the bioeconomy. This book discusses and places a common understanding of this challenge, with a strong focus on technological tools and solutions. The group of contributors brings together chemists with engineers, biologists, environmental scientists and mathematical modellers, as well as industry representatives, to show an up-to-date vision of the fate of trace elements on anaerobic biotechnologies

Biosynthesis of zinc sulfide quantum dots using waste off-gas from a metal bioremediation process

Waste H2S biogas from a mine-water remediation bioprocess is used to make zinc sulfide quantum dots which are identical to ZnS QDs made by chemical methods.</p

Vaccine breakthrough hypoxemic COVID-19 pneumonia in patients with auto-Abs neutralizing type I IFNs

Life-threatening `breakthrough' cases of critical COVID-19 are attributed to poor or waning antibody response to the SARS- CoV-2 vaccine in individuals already at risk. Pre-existing autoantibodies (auto-Abs) neutralizing type I IFNs underlie at least 15% of critical COVID-19 pneumonia cases in unvaccinated individuals; however, their contribution to hypoxemic breakthrough cases in vaccinated people remains unknown. Here, we studied a cohort of 48 individuals ( age 20-86 years) who received 2 doses of an mRNA vaccine and developed a breakthrough infection with hypoxemic COVID-19 pneumonia 2 weeks to 4 months later. Antibody levels to the vaccine, neutralization of the virus, and auto- Abs to type I IFNs were measured in the plasma. Forty-two individuals had no known deficiency of B cell immunity and a normal antibody response to the vaccine. Among them, ten (24%) had auto-Abs neutralizing type I IFNs (aged 43-86 years). Eight of these ten patients had auto-Abs neutralizing both IFN-a2 and IFN-., while two neutralized IFN-omega only. No patient neutralized IFN-ss. Seven neutralized 10 ng/mL of type I IFNs, and three 100 pg/mL only. Seven patients neutralized SARS-CoV-2 D614G and the Delta variant (B.1.617.2) efficiently, while one patient neutralized Delta slightly less efficiently. Two of the three patients neutralizing only 100 pg/mL of type I IFNs neutralized both D61G and Delta less efficiently. Despite two mRNA vaccine inoculations and the presence of circulating antibodies capable of neutralizing SARS-CoV-2, auto-Abs neutralizing type I IFNs may underlie a significant proportion of hypoxemic COVID-19 pneumonia cases, highlighting the importance of this particularly vulnerable population

Metal behaviour in anaerobic sludge digesters supplemented with trace nutrients

Trace nutrients (metals) supplementation has been demonstrated to have a beneficial effect on the welfare of anaerobic digesters but there was a lack of information on the chemistry controlling their fate. The aim of this research was to determine the reactions governing the chemical behaviour of metals in anaerobically digested sludge and predict the fate of those metals when supplemented as MeEDTA. After the assessment of a wide range of analytical techniques, a suite of suitable analytical techniques1 were used to determine the metals behaviour in two case studies of metals supplementation: iron dosing and MeEDTA supplementation. The behaviour of the metals was controlled by the solid phase throughout a primary reaction (sulphide precipitation) and secondary reactions (phosphate precipitation, adsorption and organic complexation). The competition between the strength of metal's binding and EDTA complexation controlled the fate of the supplemented metals in anaerobic digesters. Transfer of CoEDTA in the solid phase was found to be divided into two reactions, where the second has a slow kinetic depending on the availability of the counter-ion reacting with EDTA. A key conclusion was that the presence of weaker metal-bound compounds mixed with strong sulphide precipitates changed the understanding of metals speciation, especially concerning their potential availability and consequently their behaviour as trace nutrients

Trace element supplementation as a management tool for anaerobic digester operation

" This guide is intended for use by industry stakeholders, decision-makers and digester operators in navigating the topic of trace element (TE) supplementation as a management tool for anaerobic digester operation. The subject is the application of TE, and supplementation regimes in anaerobic waste-conversion biotechnologies, such as biogas digesters. TE is a term used to include a wide range of micronutrients essential for the microbial community underpinning AD. TE mostly includes elements from the metal groups (e.g. cobalt, nickel, zinc and tungsten) but also other elemental groups, such as metalloids (e.g. selenium). TE are dosed to anaerobic digesters to boost biological activity and to increase biogas production rates. Little is understood about the concentrations and dosing strategies best suited to sustained supplementation and stable performance in anaerobic biotechnologies. A range of companies offer proprietary blends of trace elements for supplementation of anaerobic digesters. Very little joined-up information is available on the concentrations of individual TE best suited to improved digester performance. Moreover, typically no attention whatsoever is paid to the bioavailability of TE dosed to digesters i.e. despite high concentrations, TE may not be available for uptake by the microorganisms underpinning the digestion process. Based on extensive engagement with a range of stakeholders throughout the course of the recent EU COST Action on ‘The ecological roles of trace metals in anaerobic biotechnologies’, and particularly on feedback from industrial partners, it is clear that such a guide is needed by industry stakeholders, decision-makers and operators of anaerobic digesters.

Trace Elements in Anaerobic Biotechnologies

The use of trace elements to promote biogas production features prominently on the agenda for many biogas-producing companies. However, the application of the technique is often characterized by trial-and-error methodology due to the ambiguous and scarce basic knowledge on the impact of trace elements in anaerobic biotechnologies under different process conditions. This book describes and defines the broad landscape in the research area of trace elements in anaerobic biotechnologies, from the level of advanced chemistry and single microbial cells, through to engineering and bioreactor technology and to the fate of trace elements in the environment. The book results from the EU COST Action on ‘The ecological roles of trace metals in anaerobic biotechnologies’. Trace elements in anaerobic biotechnologies is a critical, exceptionally complex and technical challenge. The challenging chemistry underpinning the availability of trace elements for biological uptake is very poorly understood, despite the importance of trace elements for successful anaerobic operations across the bioeconomy. This book discusses and places a common understanding of this challenge, with a strong focus on technological tools and solutions. The group of contributors brings together chemists with engineers, biologists, environmental scientists and mathematical modellers, as well as industry representatives, to show an up-to-date vision of the fate of trace elements on anaerobic biotechnologies

Trace element supplementation as a management tool for anaerobic digester operation

" This guide is intended for use by industry stakeholders, decision-makers and digester operators in navigating the topic of trace element (TE) supplementation as a management tool for anaerobic digester operation. The subject is the application of TE, and supplementation regimes in anaerobic waste-conversion biotechnologies, such as biogas digesters. TE is a term used to include a wide range of micronutrients essential for the microbial community underpinning AD. TE mostly includes elements from the metal groups (e.g. cobalt, nickel, zinc and tungsten) but also other elemental groups, such as metalloids (e.g. selenium). TE are dosed to anaerobic digesters to boost biological activity and to increase biogas production rates. Little is understood about the concentrations and dosing strategies best suited to sustained supplementation and stable performance in anaerobic biotechnologies. A range of companies offer proprietary blends of trace elements for supplementation of anaerobic digesters. Very little joined-up information is available on the concentrations of individual TE best suited to improved digester performance. Moreover, typically no attention whatsoever is paid to the bioavailability of TE dosed to digesters i.e. despite high concentrations, TE may not be available for uptake by the microorganisms underpinning the digestion process. Based on extensive engagement with a range of stakeholders throughout the course of the recent EU COST Action on ‘The ecological roles of trace metals in anaerobic biotechnologies’, and particularly on feedback from industrial partners, it is clear that such a guide is needed by industry stakeholders, decision-makers and operators of anaerobic digesters.

Ocean acidification alters the acute stress response of a marine fish

International audienceThe absorption of anthropogenic carbon dioxide from the atmosphere by oceans generates rapid changes in seawater carbonate system and pH, a process termed ocean acidification. Exposure to acidified water can impact the allostatic load of marine organism as the acclimation to suboptimal environments requires physiological adaptive responses that are energetically costly. As a consequence, fish facing ocean acidification may experience alterations of their stress re-sponse and a compromised ability to cope with additional stress, which may impact individuals' life traits and ulti-mately their fitness. In this context, we carried out an integrative study investigating the impact of ocean acidification on the physiological and behavioral stress responses to an acute stress in juvenile European sea bass. Fish were long term (11 months) exposed to present day pH/CO2 condition or acidified water as predicted by IPCC "business as usual" (RCP8.5) scenario for 2100 and subjected to netting stress (fish transfer and confinement test). Fish acclimated to acidified condition showed slower post stress return to plasma basal concentrations of cortisol and glucose. We found no clear indication of regulation in the central and interrenal tissues of the expression levels of gluco-and mineralocorticoid receptors and corticoid releasing factor. At 120 min post stress, sea bass acclimated to acidified water had divergent neurotransmitters concentrations pattern in the hypothalamus (higher serotonin levels and lower GABA and dopamine levels) and a reduction in motor activity. Our experimental data indicate that ocean acidification alters the physiological response to acute stress in European sea bass via the neuroendocrine reg-ulation of the corticotropic axis, a response associated to an alteration of the motor behavioral profile. Overall, this study suggests that behavioral and physiological adaptive response to climate changes related constraints may impact fish resilience to further stressful events