Molar Basis Research Articles

CARBON-BASED BETA-CYCLODEXTRIN ADSORBENT FOR METHYLENE BLUE AND REACTIVE ORANGE 16 REMOVAL FROM WATER

This aim of this work is to evaluate the adsorptive properties of carbon-based beta-cyclodextrin adsorbent towards Methylene Blue (MB) and Reactive Orange 16 (RO16) removal from water. The specific surface area of adsorbent is small (0.1 m2/g), with intact structure of pristine beta-cyclodextrin upon treatment. MB reaches relatively fast equilibrium (100 min), while RO16 needs more than 2200 min, despite a lower removal capacity of the former. Also, the adsorbent displays a greater affinity for MB. The kinetics data obeyed pseudofirst- order, suggesting the physical interaction of host-complex inclusion. On molar basis, the adsorption capacity of RO16 is 1.26 × 10-2 mmol/g (32 %), while that of MB is 6.8 × 10-3 mmol/g (20 %) at Co = 3.4 × 10-2 mM. To conclude, carbon-based beta-cyclodextrin is a promising adsorbent candidate for selective dyes removal from wastewater.

Structure, Mechanical, and Lytic Stability of Fibrin and Plasma Coagulum Generated by Staphylocoagulase From Staphylococcus aureus.

Staphylococcus aureus causes localized infections or invasive diseases (abscesses or endocarditis). One of its virulence factors is staphylocoagulase (SCG), which binds prothrombin to form a complex with thrombin-like proteolytic activity and leads to uncontrolled fibrin generation at sites of bacterial inoculation. The aim of this study was to characterize the formation, structure, mechanical properties and lysis of SCG-generated clots. Recombinant SCG was expressed in Escherichia coli, purified and the amidolytic activity of its complexes with human prothrombin (SCG-PT) and thrombin (SCG-T) was determined using human thrombin as a reference. Fibrin clots were prepared from purified fibrinogen and human plasma using thrombin, SCG-PT or SCG-T as a coagulase. The kinetics of clot formation and lysis by tissue-type plasminogen activator (tPA) were monitored with turbidimetric assays. Fibrin ultrastructure was examined with scanning electron microscopy and small-angle X-ray scattering (SAXS). Fibrin clot porosity was characterized with fluid permeation assays, whereas the viscoelastic properties and mechanical stability were evaluated with oscillation rheometry. Compared to thrombin, the amidolytic and clotting activity of SCG-PT was 1.6- to 2.5-fold lower on a molar basis. SCG-T had equivalent amidolytic, but reduced clotting activity both on pure fibrinogen (1.6-fold), and in plasma (1.3-fold). The SCG-PT and SCG-T generated fibrin with thicker fibers (10–60% increase in median diameter) than thrombin due to increased number of fibrin protofibrils per fiber cross-section. According to the fluid permeability of the clots SCG-PT and SCG-T promoted the formation of more porous structures. The shear stress resistance in the pure fibrin and plasma clots generated by SCG-PT was significantly lower than in the thrombin clots (243.8 ± 22.0 Pa shear stress was sufficient for disassembly of SCG-PT fibrin vs. 937.3 ± 65.6 Pa in thrombin clots). The tPA-mediated lysis of both pure fibrin and plasma clots produced by SCG-PT or SCG-T was accelerated compared to thrombin, resulting in up to a 2.1-fold increase in tPA potency. Our results indicate that SCG generates a thrombus scaffold with a structure characterized by impaired mechanical stability and increased lytic susceptibility. This proneness to clot disintegration could have implications in the septic embolism from endocardial bacterial vegetation.

Comprehensive analysis of a hybrid FO/crystallization/RO process for improving its economic feasibility to seawater desalination

In this study, the FO/crystallization/RO hybrid process was analyzed comprehensively, including experimentation, modeling, and energy and cost estimation, to examine and improve its feasibility to seawater desalination. A new operating strategy by heating the FO process to 45 °C was suggested, and a detailed process design was conducted. A comparative analysis with the conventional seawater reverse osmosis (SWRO) process was performed in terms of specific energy consumption (SEC) and specific water cost (SWC). The hybrid process can produce fresh water with SWC of 0.6964 $/m3, electrical SEC of 2.71 kWh/m3, and thermal SEC of 14.684 kWh/m3. Compared to the conventional SWRO process (SWC of 0.6890 $/m3 and electrical SEC of 2.674 kWh/m3), the hybrid process can produce water with comparable cost and energy consumption. An economic feasibility study that utilized the waste heat and the developed FO technology was also carried out to investigate future developments of the hybrid process. The SWC can be reduced to 0.6435 $/m3 with free waste heat energy. The permeate water quality of the hybrid process was about half that of the conventional SWRO process on molar basis. The results revealed that the FO/crystallization/RO hybrid process can be utilized as a competitive process for seawater desalination with high recovery and high water quality.

Effects of organic silicon compounds on syngas auto-ignition behavior

Siloxanes are a significant impurity in syngas feedstocks and an important source of silicon in combustion synthesis applications. However, little is known regarding the fundamental combustion chemistry of siloxane compounds. The impact of two organic silicon species with different but related chemical structures, trimethylsilanol (TMSO) and hexamethyldisiloxane (HMDSO), on syngas auto-ignition behavior was investigated in this study using physical and computational experiments. A rapid compression facility (RCF) was used to create temperatures of 1010–1070 K and pressures of 8–10.3 atm for auto-ignition experiments. Experiments with trace concentrations of TMSO (100 ppm, mole basis) or HMDSO (100 ppm) were added to a surrogate syngas blend (CO and H2 with a molar ratio of 2.34:1, air levels of dilution, with molar equivalence ratios of ϕ = 0.1). The measured ignition delay times showed both siloxane species promote ignition behavior with TMSO yielding faster ignition delay times by approximately 37% and HMDSO yielding faster times by approximately 50% compared with the reference syngas mixture which contained no siloxanes. A computational study was conducted to interpret the results of the ignition experiments. Because detailed chemistry does not exist for these organo-silicon compounds, the effects of the addition of CH3, H, and OH radicals to H2 and CO mixtures were explored to simulate the potential rapid decomposition of the siloxanes in the H2 and CO system. Addition of the radicals decreased the predicted ignition delay times when compared with the H2 and CO mixture simulations without the radical species, but the simulations did not fully capture the behavior observed in the experiments, indicating the siloxane chemistry is more complex than providing a rapid source of radicals.

Formulating gasoline surrogate for emulating octane blending properties with ethanol

This work develops a surrogate fuel that reproduces the octane blending of a market gasoline with ethanol. It first extends our previous investigation that reported strong, non-linear blending for ethanol/paraffin and ethanol/aromatic mixtures (Foong et al., Fuel 2014 p. 727) to consider mixtures of ethanol/cycloparaffin, ethanol/olefin, and hydrocarbons from different groups. On the molar basis, ethanol blends synergistically with cyclohexane and 1-hexene, whereas toluene blends antagonistically with ethanol and all hydrocarbons studied.Various alternative surrogate formulations are then considered given the observed inadequacy of toluene reference fuels (TRFs, mixtures of iso-octane, n-heptane, and toluene) in emulating the octane blending behaviours of a market gasoline with ethanol. These alternative surrogates are formulated to match the market gasoline’s Research Octane Number (RON) and its major hydrocarbon group composition. The best performing surrogate, which contains 38% iso-pentane, 12% n-pentane, 30% 1,2,4-trimethylbenzene, 10% cyclohexane, and 10% 1-hexene (all by volume), reproduces the RONs of the market gasoline mixed with ethanol over the entire blending range within 0.5 octane number. This surrogate formulation demonstrates that iso-pentane, n-pentane and 1,2,4-trimethylbenzene are more suitable than TRF compounds for emulating the octane blending of the gasoline/ethanol mixtures used in this study. A RON correlation is then proposed for the developed gasoline surrogate, taking into account the observed, non-linear interactions of ethanol and individual hydrocarbon compounds, which accurately predicts the RON of the surrogate/ethanol mixtures.

Roles of strontium and hierarchy structure on the in vitro biological response and drug release mechanism of the strontium-substituted bioactive glass microspheres.

The strontium (Sr) substituted bioactive glasses (BGs) have inimitable advantages for bone generation, but the influences of Sr substitution on bioactivity and biocompatibility are still in debate. A brand novel porous microstructure of Sr-substituted BG microspheres was prepared by an electro-spraying technique combined with phase inversion, in which in vitro biological response (bioactivity, cell viability, alkaline phosphatase (ALP) activity and extracellular matrix (ECM) mineralization) and drug release were clarified in view of physical chemistry and ionic release behavior. The electro sprayed bioactive glass (ESBG) microspheres involved three characteristic pores: <100 nm, 100-1000 nm and >1000 nm. The Sr substitution on molar basis hindered the bioactivity of the samples in some extent but the cell behavior of the MC3T3-E1 cells was not significantly discouraged. The drug release profile was also controlled by amount of Sr substitution. However, the porous structure of the microspheres conferred improvement in bioactivity and provided a distinct three-stage drug release mode. Therefore, the Sr substituted ESBG microspheres may provide an effective way to deliver a steady supply of therapeutic ions and drugs in bone implantation patients.

Modeling post-flame sulfation of KCl and KOH in bio-dust combustion with full and simplified mechanisms

The gas-phase interaction between alkali volatiles and sulphur oxides has important implications for deposition and corrosion in combustion of biomass. In the present study, gas-phase transformation of KOH and KCl in the post-flame zone in bio-dust combustion has been studied by detailed chemical kinetic modeling for a woody and a herbaceous biomass, respectively. For both biomasses K > Cl on a molar basis, and KOH is the major alkali species at high temperature. The modeling indicates that KOH is readily converted to K2SO4 in the presence of SO2 at temperatures below 1500 K. Below 1100 K, gaseous K2SO4 nucleates homogeneously, promoting further sulfation. For the woody biomass, where K < Cl + 2S, the sulfation process is kinetically limited due to the competition with chlorination. For the herbaceous biomass, with K > Cl + 2S, the excess KOH facilitates internal equilibration among the alkali species. For both biomasses, the KCl concentration remains constant during sulfation, because any KCl consumed is rapidly replenished by the reaction KOH + HCl ⇄ KCl + H2O. The consequence is that the sulfation process under the investigated conditions does not help to remove the main corrosive agent, KCl. For use in CFD, a skeletal model for the gas-phase sulfation of KCl and KOH has been developed, based on systematic reduction of the detailed chemical kinetic model. However, for fuels with excess K compared to Cl + 2S, a simple equilibrium calculation may yield satisfactory results.

Dietary reference values for chloride.

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) has derived dietary reference values (DRVs) for chloride. There are no appropriate biomarkers of chloride status, no balance studies and no adequate evidence on the relationship between chloride intake and health outcomes that can be used to set DRVs for chloride. There is a close relationship between sodium and chloride balances in the body. Sodium chloride is the main source of both electrolytes in European diets and similar urinary excretion levels of sodium and chloride (on a molar basis) are typically observed in Western populations. Hence, the Panel considered that reference values for chloride can be set at values equimolar to the reference values for sodium for all population groups, and are as follows: 1.7 g/day for children aged 1–3 years, 2.0 g/day for children aged 4–6 years, 2.6 g/day for children aged 7–10 years, 3.1 g/day for children aged 11–17 years and 3.1 g/day for adults including pregnant and lactating women. Consistent with the reference values for sodium, these levels of chloride intake are considered to be safe and adequate for the general EU population, under the consideration that the main dietary source of chloride intake is sodium chloride. For infants aged 7–11 months, an adequate intake of 0.3 g/day is set.

Influence of water-vapor in oxidizer stream on the sooting behavior for laminar coflow ethylene diffusion flames

The effects of adding water-vapor to the oxidizer stream on soot production in laminar coflow diffusion flames under different oxygen indices (OI) were investigated both experimentally and numerically. A modified coflow Gülder-type burner was employed to produce the laminar ethylene flames for fifteen different conditions of the oxidizer stream from oxygen-deficient (OI 17%) to oxygen-enriched (OI 25%) conditions, and also without and with adding water-vapor into the oxidizer stream up to 10% on mole basis. The measured soot volume fractions were compared with numerical predictions obtained using the CoFlame code and a chemical kinetic mechanism that consists of reaction pathways up to 5-ring PAHs. The sectional soot model used to simulate the soot particles dynamics considers soot nucleation, surface growth, PAH condensation, oxidation, particle coagulation and fragmentation. Fairly good agreement between experimental and numerical results was found, as close as 1% and 5% of difference in the peak soot volume fraction for OI21% with 0% and 10% of water-vapor addition, respectively. Clear trends of increasing the soot volume fraction (peak and also overall) was observed with increasing OI, while a significant reduction was obtained with the addition of the water-vapor. For the cases analyzed, a reduction of the total soot content was up to 60%. The chemical effects were numerically isolated using non-reacting water-vapor and analyzed, contributing especially to the soot oxidation rates. Finally, a study of the main reaction pathways was performed to better understand the chemical effects of water vapor. The results show that water vapor addition affects the concentrations of H and OH radicals and alters the formation and oxidation of soot precursors.

Preparation and characterization of a polyester-etheramide hot melt adhesive system from renewable resources

A polyester-etheramide (PEEA) based hot melt adhesive (HMA) was successfully designed containing a high content of renewable mass. The PEEA HMA was synthesized based on dimer acid (DA), ethylenediamine (EDA), karanja oil and resorcinol. Karanja oil was reacted with diethanolamine to prepare N–N-bis (2-hydroxyethyl) karanja oil fatty amide (HEKA). Resorcinol was reacted with DA with varying concentrations of resorcinol of 0%, 5%, 10% and 15% on a molar basis. The effects of resorcinol and HEKA on the properties of the hot melt were investigated. The synthesized products were characterized by end group analysis, FTIR, DSC, XRD and the rheological, adhesion and mechanical properties assessed. It was observed that the mechanical and thermal properties increased with increasing concentration of resorcinol. These HMA materials could hold potential for sustainability and high adhesive performance.

Selective Cellulose Hydrogenolysis to Ethanol Using Ni@C Combined with Phosphoric Acid Catalysts.

Ethanol is an important bulk chemical with diverse applications. Biomass-derived ethanol is traditionally produced by fermentation. Direct cellulose conversion to ethanol by chemocatalysis is particularly promising but remains a great challenge. Herein, a one-pot hydrogenolysis of cellulose into ethanol was developed by using graphene-layers-encapsulated nickel (Ni@C) catalysts with the aid of H3 PO4 in water. The cellulose was hydrolyzed into glucose, which was activated by forming cyclic di-ester bonds between the OH groups of H3 PO4 and glucose, promoting ethanol formation under the synergistic hydrogenation of Ni@C. A 69.1 % yield of ethanol (carbon mole basis) was obtained, which is comparable to the theoretical value achieved by glucose fermentation. An ethanol concentration of up to 8.9 wt % was obtained at an increased cellulose concentration. This work demonstrates a chemocatalytic approach for the high-yield production of ethanol from renewable cellulosic biomass at high concentration.

Citicoline: A Superior Form of Choline?

Medicines containing citicoline (cytidine-diphosphocholine) as an active principle have been marketed since the 1970s as nootropic and psychostimulant drugs available on prescription. Recently, the inner salt variant of this substance was pronounced a food ingredient in the major world markets. However, in the EU no nutrition or health claim has been authorized for use in commercial communications concerning its properties. Citicoline is considered a dietetic source of choline and cytidine. Cytidine does not have any health claim authorized either, but there are claims authorized for choline, concerning its contribution to normal lipid metabolism, maintenance of normal liver function, and normal homocysteine metabolism. The applicability of these claims to citicoline is discussed, leading to the conclusion that the issue is not a trivial one. Intriguing data, showing that on a molar mass basis citicoline is significantly less toxic than choline, are also analyzed. It is hypothesized that, compared to choline moiety in other dietary sources such as phosphatidylcholine, choline in citicoline is less prone to conversion to trimethylamine (TMA) and its putative atherogenic N-oxide (TMAO). Epidemiological studies have suggested that choline supplementation may improve cognitive performance, and for this application citicoline may be safer and more efficacious.

Esterification of geraniol as a strategy for increasing product titre and specificity in engineered Escherichia coli

BackgroundGeraniol, an acyclic monoterpene alcohol, is found as a primary constituent in the essential oils of plants such as geranium, lemongrass and rose. The floral-like scent of geraniol has made it a popular constituent of flavour and fragrance products. Over recent decades biotechnology has made significant progress towards the development of industrial platforms for the production of commercially valuable monoterpenoids, such as geraniol, through expression of recombinant terpene biosynthetic pathways in microbial hosts. Titres, however, have been hindered due to the inherent toxicity of these compounds—which are often utilised for anti-microbial and anti-fungal functions in their host plant.ResultsIn this study we modified an Escherichia coli strain, engineered to express a heterologous mevalonate pathway, by replacement of the terpene synthase with a geraniol synthase from Ocimum basilicum for the production of geraniol, and co-expressed an alcohol acyltransferase (AAT) from Rosa hybrida for the specific acetylation of geraniol. The low water solubility of geranyl acetate facilitated its partition into the organic phase of a two-phase system, relieving the cellular toxicity attributed to the build-up of geraniol in the aqueous phase. In a partially optimised system this strain produced 4.8 g/L geranyl acetate (based on the aqueous volume) which, on a molar equivalent basis, represents the highest monoterpene titre achieved from microbial culture to date. It was also found that esterification of geraniol prevented bioconversion into other monoterpenoids, leading to a significant improvement in product specificity, with geranyl acetate being the sole product observed.ConclusionIn this study we have shown that it is possible to both overcome the toxicity limit impeding the production of the monoterpene alcohol geraniol and mitigate product loss in culture through endogenous metabolism by using an in vivo esterification strategy. This strategy has resulted in the highest geraniol (equivalent) titres achieved from a microbial host, and presents esterification as a viable approach to increasing the titres obtained in microbial monoterpenoid production.

Thermodynamic properties of microorganisms: determination and analysis of enthalpy, entropy, and Gibbs free energy of biomass, cells and colonies of 32 microorganism species

Thermodynamic analysis is an important part of chemical engineering. However, its application in biotechnology has been hampered by lack of data on thermodynamic properties of microorganism biomass. In this paper, a review was made of methods for estimation of thermodynamic properties of biomass, including standard enthalpy of combustion hC⁰, enthalpy of formation hf⁰, entropy s⁰, and Gibbs free energy of formation gf⁰. These parameters were calculated on molar and mass specific basis for 32 microorganism species, including 14 bacteria, 7 yeast and 11 algae species. It was found that hf⁰, s⁰, gf⁰ are, respectively, similar for all the analyzed species, due to the fact that all living organisms have a common ancestor and thus a similar chemical composition. Furthermore, all the analyzed microorganisms have negative hf⁰, originating from partial oxidation of all other elements by oxygen and nitrogen. A brief review was given of microorganism endogenous and growth metabolic rates. Finally, based on the determined thermodynamic properties, entropy of individual E. coli and Pseudomonas cells were determined and entropy of a Pseudomonas colony during its lifespan was calculated and analyzed. Three periods can be distinguished in the existence of a microorganism colony: (a) accumulation period when cell number, mass and entropy increase, (b) steady state period when they are approximately constant, and (c) decumulation period when they decrease.

Simultaneous adsorption of Cd2+ , Ni2+ and Pb2+ on peat

The aim of the present work was to investigate iflocally available untreated peat could beused as filter material for the removal of heavy metals from leachate. The aqueoussolutions containing Cd2+, Ni2+ and Pb2+ ions in single-metal and multi-metal solutionswere used to study the adsorption of metals on peat. The peat was obtained fromSouthern Estonia. The decomposition rate of the peat was H6-H7 on the von Post scale.In order to assess the adsorption mechanism, the amounts of Ca2+ and Mg2+ ions desorbedfrom untreated peat were measured and compared to the adsorption efficiency of Cd2+,Ni2+ and Pb2+ ions from solution on the peat. The desorption of other cations, such asAl3+, K+, Na+, Fe3+, Zn2+ etc. were negligible during all experiments. Adsorption batchisotherm studies were carried out by using IO experimental series with the initialconcentration of 10 - 300 mg/I. The samples were analyzed by using the axial ICP-AES.Results of the single- as well as multi-metal adsorptions show that peat can be effectivelyused. Adsorption of metals on molar basis was found in the indicated order: Pb2+ &gt; Cd2+&gt; Ni2+. The removal of single metal ions from ternary-metal solution was less than itsremoval from single-metal solution. However, the total adsorption capacity of metalsfrom multi-metal solution to peat increased. The Langmuir isotherm equation constantswere calculated and isotherms were drawn by using the program of calculating hyperbolefunctions. Correlations for Ni2+ and Cd2+ with the Langmuir isotherm equation was foundto be good, whereas for Pb2+ the plot (amount absorbed vs. the equilibrium aqueousconcentration) was linear.

Biomass gasification in microwave plasma: An experimental feasibility study with a side stream from a fermentation reactor

In this work, we report on air/N2 gasification of a byproduct stream from an industrial fermenter in a tubular microwave plasma reactor to investigate the feasibility of the technology for organic compounds valorization, given the limited number of relevant works in the literature. In this context, an operating window regarding air/N2/biomass flow rates and power input has been identified to enable stable and efficient operation. Up to 89% carbon conversion efficiency and 41% cold gas efficiency have been attained with syngas product composition H2:CO:CO2 = 41:53:6 on molar basis, fairly close to the calculated equilibrium composition values in the temperature range 973 K to 2173 K.

Small Amounts of Inorganic Nitrate or Beetroot Provide Substantial Protection From Salt-Induced Increases in Blood Pressure.

To reduce the risk of salt-induced hypertension, medical authorities have emphasized dietary guidelines promoting high intakes of potassium and low intakes of salt that provide molar ratios of potassium to salt of ≥1:1. However, during the past several decades, relatively few people have changed their eating habits sufficiently to reach the recommended dietary goals for salt and potassium. Thus, new strategies that reduce the risk of salt-induced hypertension without requiring major changes in dietary habits would be of considerable medical interest. In the current studies in a widely used model of salt-induced hypertension, the Dahl salt-sensitive rat, we found that supplemental dietary sodium nitrate confers substantial protection from initiation of salt-induced hypertension when the molar ratio of added nitrate to added salt is only ≈1:170. Provision of a low molar ratio of added nitrate to added salt of ≈1:110 by supplementing the diet with beetroot also conferred substantial protection against salt-induced increases in blood pressure. The results suggest that on a molar basis and a weight basis, dietary nitrate may be ≈100× more potent than dietary potassium with respect to providing substantial resistance to the pressor effects of increased salt intake. Given that leafy green and root vegetables contain large amounts of inorganic nitrate, these findings raise the possibility that fortification of salty food products with small amounts of a nitrate-rich vegetable concentrate may provide a simple method for reducing risk for salt-induced hypertension.

A New Estimate of the Glomerular Sieving Coefficient for Retinol-Binding Protein 4 Suggests It Is Not Freely Filtered

A New Estimate of the Glomerular Sieving Coefficient for Retinol-Binding Protein 4 Suggests It Is Not Freely Filtered

Net reduction of CO2 via its thermocatalytic and electrocatalytic transformation reactions in standard and hybrid processes

Many research efforts into CO2 reduction to valuable products are motivated by a desire to reduce the atmospheric CO2 concentration. However, it is unclear how laboratory-scale catalytic performance translates to the goal of reducing CO2. In this Perspective, we analyse recently reported thermocatalytic and electrocatalytic performances for reduction of CO2 to methanol in terms of net CO2 reduction, on a mole basis. Our calculations indicate that even an ideal catalytic process needs to be powered by electricity emitting less than 0.2 kg of CO2 per kWh to achieve a net reduction in CO2. We conclude that hybrid processes combining thermocatalysis and electrocatalysis are promising opportunities to reduce CO2 to methanol, as long as practical electrocatalysts achieve reaction rates two orders of magnitude larger than those observed in current laboratory tests. In such a scenario, an increase in the global methanol market could benefit the overall reduction of atmospheric CO2 via conversion of CO2 to methanol. CO2 hydrogenation is frequently acclaimed as a strategy for greenhouse gases mitigation, although the carbon footprint of the corresponding electrocatalytic or thermocatalytic process is often neglected. This Perspective analyses the amount of CO2 generated during methanol production for different catalytic processes and hybrid thereof.

Increasing the Selectivity for Sulfur Formation in Biological Gas Desulfurization.

In the biotechnological desulfurization process under haloalkaline conditions, dihydrogen sulfide (H2S) is removed from sour gas and oxidized to elemental sulfur (S8) by sulfide-oxidizing bacteria. Besides S8, the byproducts sulfate (SO42–) and thiosulfate (S2O32–) are formed, which consume caustic and form a waste stream. The aim of this study was to increase selectivity toward S8 by a new process line-up for biological gas desulfurization, applying two bioreactors with different substrate conditions (i.e., sulfidic and microaerophilic), instead of one (i.e., microaerophilic). A 111-day continuous test, mimicking full scale operation, demonstrated that S8 formation was 96.6% on a molar H2S supply basis; selectivity for SO42– and S2O32– were 1.4 and 2.0% respectively. The selectivity for S8 formation in a control experiment with the conventional 1-bioreactor line-up was 75.6 mol %. At start-up, the new process line-up immediately achieved lower SO42– and S2O32– formations compared to the 1-bioreactor line-up. When the microbial community adapted over time, it was observed that SO42– formation further decreased. In addition, chemical formation of S2O32– was reduced due to biologically mediated removal of sulfide from the process solution in the anaerobic bioreactor. The increased selectivity for S8 formation will result in 90% reduction in caustic consumption and waste stream formation compared to the 1-bioreactor line-up.