Characterization of magnetite assisted anammox granules based on in-depth analysis of extracellular polymeric substance (EPS).

Magnetite can be considered as an iron-rich carrier particles that can be ionized into Fe2+ and Fe3+ which improves the activity and aggregation of anammox bacteria. Three samples from this carrier assisted granulation reactor with size groups including Flocs, FL (0-300 µm), Small Granules, SG (300-500 µm) and Large Granules, LG (500-1000 µm) were used in this study. It was observed that as the granule size increased, the iron-rich carrier content increased, and their active crystals improved the microbial cell density. Specific anammox activity (SAA) was 34.63 ± 5.02, 55.29 ± 5.14, and 63.81 ± 7.50 mg-N/g-VSS/d for FL, SG and LG, respectively. In addition, in heme c content of LG was 31.5 % higher than SG and 62.9 % higher than FL. An in-depth study into the extracellular polymeric substances (EPS) showed that the secretion intensity of essential proteins followed the order of FL < SG < LG in loosely bound EPS and FL > SG > LG in tightly bound EPS. Functional group analysis confirmed that the hydrophobic CN and NH stretching vibration band had almost 3.5 times higher transmittance intensity in LG than the other sizes and the corresponding ratio of α-helix/(ß sheet + random coil) in secondary derivative proteins analysis showed tightness in the protein structures of FL. The relative abundance of Brocadia Sinica increased from 0 % in FL to a high of 20.46 % in LG. This study aims to communicate the essence of in-depth EPS analysis beyond the usual EPS yield and major contents of proteins (PN) and polysaccharides (PS) analysis.

Mercury and other trace elements distribution and profiling of microbial community in the surface sediments of East Siberian Sea.

In this study, total mercury (THg), methylmercury (MeHg), various trace elements, and microbial communities were measured in surface sediments of the East Siberian Sea (ESS). The results showed that the average values of THg and MeHg were 58.8 ± 15.21 µg/kg and 0.50 ± 0.22 µg/kg, respectively. The notable levels of trace elements present in both surface sediment and porewater were Al, Fe, and Mn. The enrichment factor and geoaccumulation index analyses found that both natural phenomena and anthropogenic activities contributed to elevated concentrations of metals in the ESS. The redox proxy metals, pH, and SO42- were the major factors influencing the THg and MeHg distributions. Microbial profiles were substantially affected by metals and other abiotic factors. Proteobacteria and Thaumarchaeota were the most abundant phyla. Overall, the findings presented here facilitate the understanding of the current status of metal contamination, its influencing factors, and metal-microbiota-interactions in ESS.

CO2 as an Alternative to Traditional Antiscalants in Pressure-Driven Membrane Processes: An Experimental Study of Lab-Scale Operation and Cleaning Strategies.

Scaling, or inorganic fouling, is a major factor limiting the performance of membrane-based water treatment processes in long-term operation. Over the past few decades, extensive studies have been conducted to control the scale growth found in membrane processes and to develop sustainable and greener processes. This study details the role of CO2 in scale inhibition in membrane processes. The core concept of CO2 utilization is to reduce the influent pH and to minimize the risk of scale formation from magnesium or calcium salts. Three reverse osmosis (RO) units were operated with a control (U1), CO2 (U2), and a commercial antiscalant, MDC-220 (U3). The performances of all the units were compared in terms of change in transmembrane pressure (TMP). The overall efficiency trend was found as U1 > U3 > U2. The membrane surfaces were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) for the morphological and elemental compositions, respectively. The surface analysis signified a significant increase in surface smoothness after scale deposition. The noticeable reduction in surface roughness can be described as a result of ionic deposition in the valley region. A sludge-like scale layer was found on the surface of the control membrane (U1) which could not be removed, even after an hour of chemical cleaning. After 20−30 min of cleaning, the U2 membrane was successfully restored to its original state. In brief, this study highlights the sustainable membrane process developed via CO2 utilization for scale inhibition, and the appropriate cleaning approaches.

The role of magnetite (Fe3O4) particles for enhancing the performance and granulation of anammox.

In this study, two lab-scale sequencing batch reactors each with an effective volume of 2.3 L were operated as C-AMX (no carrier addition) and M-AMX (magnetite carrier added) for 147 days with synthetic wastewater at an NLR range of 0.19-0.47 kgN/m3/d. The long-term effect of magnetite on the granulation and performance of anammox bacteria in terms of nitrogen removal and other essential parameters were confirmed. In phase I (1-24 days), M-AMX took approximately 12 days to obtain a nitrogen removal rate (NRR) above 80 % of the initial input nitrogen. Although free nitrous acid inhibited the reactor at a high concentration at the onset of phase III, the NRR of M-AMX recovered about 3.7 times faster than that of C-AMX. In addition, it was confirmed that the M-AMX granules had a dense and compact structure compared to C-AMX, and the presence of the carrier promoted the development of these resilient granules. While the measured microbial stress gradually increased in C-AMX reactor, a vice versa was observed in the M-AMX reactor as granulation proceeded. Compared to other alternative iron-based carrier particles, the stable crystal structure of magnetite as a carrier created a mechanism where filamentous bacteria groups were repelled from the granulation hence the microbial stress in the M-AMX in the final phase was 61.54 % lower than that in the C-AMX. The iron rich environment created by the magnetite addition led to Ignavibacteria, (a Feammox bacteria) increasing significantly in the M-AMX bioreactor.

Current advances in the classification, production, properties and applications of microbial biosurfactants - A critical review.

This review discusses the classification, characteristics, and applications of biosurfactants. The biosynthesis pathways for different classes of biosurfactants are reviewed. An in-depth analysis of reported research is carried out emphasizing the synthetic pathways, culture media compositions, and influencing factors on production yield of biosurfactants. The environmental, pharmaceutical, industrial, and other applications of biosurfactants are discussed in detail. A special attention is given to the biosurfactants application in combating the pandemic COVID-19. It is found that biosurfactant production from waste materials can play a significant role in enhancing circular bioeconomy and environmental sustainability. This review also details the life cycle assessment methodologies for the production and applications of biosurfactants. Finally, the current status and limitations of biosurfactant research are discussed and the potential areas are highlighted for future research and development. This review will be helpful in selecting the best available technology for biosynthesis and application of particular biosurfactant under specific conditions.

Distinctive differences in the granulation of saline and non-saline enriched anaerobic ammonia oxidizing (AMX) bacteria.

The growing interest in the anaerobic ammonium oxidizing (AMX) process in treating high nitrogen containing wastewaters and a comprehensive study into the granulation mechanism of these bacteria under diverse environmental conditions over the years have been unequal. To this effect, the distinctive differences in saline adapted AMX (S_AMX) and non-saline adapted AMX (NS_AMX) granules are presented in this study. It was observed that substrate utilisation profiles, granule formation mechanism, and pace towards granulation differed marginally for the two adaptation conditions. The different microbial dominant aggregation types aided in splitting the 471 days operated lab-scale SBRs into three distinct phases. In both reactors, phase III (granules dominant phase) showed the highest average nitrogen removal efficiency of 87.9% ± 4.8% and 85.6% ± 3.6% for the S_AMX and NS_AMX processes, respectively. The extracellular polymeric substances (EPS) quantity and major composition determined its role either as a binding agent in granulation or a survival mechanism in saline adaptation. It was also observed that granules of the S_AMX reactor were mostly loosely and less condensed aggregates of smaller sub-units and flocs while those of the NS_AMX reactor were compact agglomerates. The ionic gradient in saline enrichment led to an increased activity of the Na+/K+ - ATPase, hence enriched granules produced higher cellular adenosine triphosphate molecules which finally improved the granules active biomass ratio by 32.96%. Microbial community showed that about three to four major known AMX species made up the granules consortia in both reactors. Proteins and expression of functional genes differed for these different species.

A comprehensive root cause analysis of anammox bioreactor performance decline.

The cultivation of anaerobic ammonia oxidizing bacteria (anammox) has gained enormous awareness over the last few decades. Although numerous studies focus massively on successfully growing these anammox to different enrichment environments, in reality, the failure rates are somewhat comparable to the reported success rates. This study combines a variety of measurement techniques to observe and monitor the sequence of a bioreactor performance decline following elevated influent substrate concentration. After attaining stable substrate removal throughout a nitrogen loading rate (NLR) range of 0.691 to 1.669 kg-N·m-3·d-1, the performance of the lab-scale anammox-sequencing batch reactor (SBR) abruptly broke down as the NLR reached 2.01 kg-N·m-3·d-1. The gathered information showed that the increased NLR firstly caused a significant and unfavorable change in the free ammonia (FA) and free nitrous acid (FNA) concentration in the bioreactor. A subsequent drop in N2 production and a decline from a peak high of 0.381 to a low of 0.012 kg-N·kg-VSS-3·d-1 of the specific nitrogen removal rate (SNRR) led to an 82% absurd decline in microbial cellular energy production. Prior to these anammox switching to survival mode and secreting larger quantities (32% higher) of extracellular polymeric substances (EPS), the activity of syntrophic decomposers increased substantially leading to the internal production of excess CO2 in the bioreactor and thereby diverging the bioreactor pH to lower levels. The purposes of this study are to understand the reason an anammox process shows different signals during a decline phase and to enable immediate response to performance deterioration.

Sustainable Membrane-Based Wastewater Reclamation Employing CO2 to Impede an Ionic Precipitation and Consequent Scale Progression onto the Membrane Surfaces.

CO2 capture and utilization (CCU) is a promising approach in controlling the global discharge of greenhouse gases (GHG). This study details the experimental investigation of CO2 utilization in membrane-based water treatment systems for lowering the potential of ionic precipitation on membrane surface and subsequent scale development. The CO2 utilization in feed water reduces the water pH that enables the dissociation of salts in their respective ions, which leave the system as a concentrate. This study compares the efficiency of CO2 and other antifouling agents (CA-1, CA-2, and CA-3) for fouling control in four different membrane-based wastewater reclamation operations. These systems include Schemes 1, 2, 3, and 4, which were operated with CA-1, CA-2, CA-3, and CO2 as antiscalants, respectively. The flux profile and percent salt rejection achieved in Scheme 4 confirmed the higher efficiency of CO2 utilization compared with other antifouling agents. This proficient role of CO2 in fouling inhibition is further endorsed by the surface analysis of used membranes. The SEM, EDS, and XRD examination confirmed the higher suitability of CO2 utilization in controlling scale deposition compared with other antiscalants. The cost estimation also supported the CO2 utilization for environmental friendly and safe operation.

From freshwater anammox bacteria (FAB) to marine anammox bacteria (MAB): A stepwise salinity acclimation process.

An investigation into the effect of stepwise saline introduction (3-20 g·L-1 NaCl) on the anaerobic ammonium oxidation (anammox) process in a lab-scale sequencing batch reactor was carried out for 252 days by evaluating the changes in influent and effluent nitrogen concentrations, conductivity, microbial extracellular polymeric substances' (EPS) ionic content, as well as stresses due to salinity, via microbial ATP analysis. It was observed that, effluent nitrogen concentrations remained stable at low saline levels of 3 g·L-1 to 10 g·L-1. Nonetheless, midway through 10 g·L-1 and the preliminary phase of 15 g·L-1 salinity presented a very unstable, highly fluctuating as well as deteriorating effluent nitrogen concentrations. A more satisfactory nitrogen removal efficiency of 83.7 ± 5.9% was obtained at higher saline concentrations implying that, the adaptation mechanism to tolerate increasing salinity was taking place. Saline induced stress, which measures the variation in viable anammox bacteria, was correlative to the formation of EPS and changes in its cationic contents along the increasing salinity. Although the specific anammox activity (SAA) dropped by approximately 15% from the beginning of the process to the midpoint, the drop in SAA after the midpoint was not as drastic as the initial phase. A change in microbial aggregation and dominance proved the existence of new saline-dependent species that can withstand high saline stresses. Recovery from abrupt high saline shocks in batch experiment was seen to be almost impossible.

Biofuels and biorefineries: Development, application and future perspectives emphasizing the environmental and economic aspects.

The fossil fuel utilization adversely affected the environmental health due to the rising emission levels of greenhouse gases. Consequently, the challenges of climate change loaded great stress on renewable energy sources. It is noted that extreme consumption of fossil fuels increased the earth temperature by 1.9 °C that adversely influenced the life and biodiversity. Biorefinery is the sustainable process for the production of biofuels and other bio-products from biomass feedstock using different conversion technologies. Biofuel is an important component of renewable energy sources contributing to overall carbon-neutral energy system. Studies reported that on global scale, over 90% of petroleum goods could be produced from renewable resources by 2023, whereas, 33% chemicals, and 50% of the pharmaceutical market share is also expected to be bio-based. This study details the brief review of operation, development, application, limitations, future perspectives, circular bioeconomy, and life cycle assessment of biorefinery. The economic and environmental aspects of biofuels and biorefineries are briefly discussed. Lastly, considering the present challenges, the future perspectives of biofuels and biorefineries are highlighted.

Saline conditions effect on the performance and stress index of anaerobic ammonium oxidizing (anammox) bacteria.

In this study, a lab-scale sequencing batch reactor dominated by freshwater anammox bacteria (FAB) was used to study the performance and stress index of the anammox bacteria at various saline conditions. The reactor with an effective volume of 1.8 L was operated for about 160 days. The nitrogen-loading rate was maintained at 0.364 kg-N m-3d-1 throughout the operational period. At the start-up phase, the seed biomass acclimation to the lab bioreactor showed an inconsistent performance. However, a stable performance was observed after day 38. The average substrate removal efficiency was 92% during most of the operational period. Anammox stress index; a ratio of dissolved Adenosine Triphosphate (dATPamx) to total Adenosine Triphosphate (tATPamx) showed an irrefutable correlation between NaCl concentration, anammox stress and microbial community. A drop in the biomass cellular ATP at 5 g L-1 salinity led to a significant decrease in the Specific Anammox activity. Candidatus Brocadia was identified as the main anammox species and its relative abundance reduced along the stepwise salinity increment.

A brief review of anaerobic membrane bioreactors emphasizing recent advancements, fouling issues and future perspectives.

This review summarizes the recent development and studies of anaerobic membrane bioreactor (AnMBR) to control fouling issues. AnMBR is an emerging waste water treatment technology mainly because of its low sludge residual, high volumetric organic removal rate, complete liquid-solid separation, better effluent quality, efficient resource recovery and the small footprint. This paper surveys the fundamental aspects of AnMBRs, including its applications, membrane configurations, and recent progress for enhanced reactor performance. Furthermore, the membrane fouling, a major restriction in the practical application of AnMBR, its mechanism and antifouling strategies like membrane cleaning, quorum quenching, ultrasonic treatment, membrane modifications, and antifouling agents are briefly discussed. Based on the review, the key issues that require urgent attention to facilitate large scale and integrated application of AnMBR technology are identified and future research perspectives relating to the prevalent issues are proposed.

Inorganic fouling control in reverse osmosis wastewater reclamation by purging carbon dioxide.

Inorganic fouling on the membrane surface is one of the major prevalent issues affecting the performance and cost of reverse osmosis system. Chemical dosage is a widely adopted method for the inhibition of inorganic scale on the membrane surface. In this study, CO2 was used to control inorganic scale formation on surface of reverse osmosis (RO) membrane in wastewater reclamation. The pH of influent could be lowered by purging CO2. It caused an increase in solubility of inorganic salts in water resulting in discharge of principle ions in concentrate stream. A pilot plant study was conducted with four different RO modules including control, with dosage of antiscalant, with purging CO2 and with co-addition of antiscalant and CO2. The effectiveness of CO2 purging was assessed on the basis of operational analysis, in-line analysis and morphological results. Ryznar stability index was used to determine the scaling potential of system. The examined data indicated that CO2 purging was successful to inhibit scale formation on the membrane surface. Moreover, CO2 was found more eco-friendly than antiscalant, as no by-products were generated in concentrate stream.

Synthesis of magnetite from raw mill scale and its application for arsenate adsorption from contaminated water.

The magnetite particles were chemically synthesized from the waste of hot rolling steel industry. The characterization of the synthesized magnetite was done by using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The synthesized magnetite particles were used for the adsorptive removal of arsenate from the contaminated water. The maximum adsorption capacity of 7.69 mg was found on the surface of 1 g of the magnetite. The point of zero charge for magnetite is determined at the pH 6. The adsorption capacity of magnetite particles was successfully restored with alkali cleaning. Newly synthesized particles were found to be effective for arsenate removal up to 5 times with regeneration. The synthesis of magnetite from raw mill scale and its application for arsenate adsorption is a cost effective and ecofriendly process.

A comprehensive overview on electro-active biofilms, role of exo-electrogens and their microbial niches in microbial fuel cells (MFCs).

Microbial fuel cells (MFCs) are biocatalyzed systems which can drive electrical energy by directly converting chemical energy using microbial biocatalyst and are considered as one of the important propitious technologies for sustainable energy production. Much research on MFCs experiments is under way with great potential to become an alternative to produce clean energy from renewable waste. MFCs have been one of the most promising technologies for generating clean energy industry in the future. This article summarizes the important findings in electro-active biofilm formation and the role of exo-electrogens in electron transfer in MFCs. This study provides and brings special attention on the effects of various operating and biological parameters on the biofilm formation in MFCs. In addition, it also highlights the significance of different molecular techniques used in the microbial community analysis of electro-active biofilm. It reviews the challenges as well as the emerging opportunities required to develop MFCs at commercial level, electro-active biofilms and to understand potential application of microbiological niches are also depicted. Thus, this review is believed to widen the efforts towards the development of electro-active biofilm and will provide the research directions to overcome energy and environmental challenges.

Greater trochanteric pain syndrome due to tumoral calcinosis in a patient with chronic kidney disease.

Tumoral calcinosis is a rare syndrome characterized by massive subcutaneous soft tissue deposits of calcium phosphate near the large joints. It is more prevalent in patients with chronic kidney disease undergoing dialysis. A 57-year-old woman was referred to our pain clinic with the complaint of severe pain in the left buttock and lateral hip. The patient had been suffering from chronic kidney disease for 10 years and had been undergoing peritoneal dialysis over the past 5 years. The patient's symptom was initially suspected to be of lumbar origin at the L5 level and a left L5 transforaminal epidural block was performed, but without success. Re-evaluation of the physical examination revealed severe tenderness over the left greater trochanter and piriformis muscle. On ultrasonographic evaluation, multiple mass-like lesions in the left buttock were observed. About 30 mL of fluid was aspirated from the cystic lesions, followed by 30 mL mixture of 0.08% levobupivacaine and triamcinolone 40 mg injected into the bursa under ultrasound guidance, which brought pain relief. Trochanteric bursitis was thought of as the cause of the symptoms. The patient was diagnosed with tumoral calcinosis based on the past medical history, simple plain radiographs, and hip magnetic resonance imaging (MRI). We diagnosed a case of greater trochanteric pain syndrome due to tumoral calcinosis related to chronic kidney disease in a patient whose symptoms had initially been considered to be radiating leg pain caused by lumbar spinal disease. We report our experience of symptomatic improvement following the repeated ultrasound-guided aspiration of calcific fluid and the injection of a mixture of local anesthetic and steroid.

Dexmedetomidine and remifentanil in the perioperative management of an adolescent undergoing resection of pheochromocytoma -A case report-.

A 15-year-old adolescent with unilateral multiple adrenal pheochromocytoma had an episode of subcortical intracerebral hemorrhage and seizure 6 weeks before the surgery. He was pretreated with terazosin, losartan, atenolol and levetiracetam for 2 weeks. Dexmedetomidine was started in the preoperative waiting area, and a combination of dexmedetomidine and remifentanil was continuously infused for most of anesthetic time. To control blood pressure, bolus injection of remifentanil and low-dose infusion of sodium nitroprusside, nicardipine, and esmolol were administered during three adrenergic crises. There was minimal post-resection hypotension, and his trachea was extubated safely 20 min after the surgery. He was discharged without noticeable complication. His catecholamine levels showed the steadily decreasing pattern during the operation in this case. Though a combination of dexmedetomidine and remifentanil may not prevent the hemodynamic instability impeccably during the tumor manipulation, this combination seems to be the way of interrupting release of catecholamines and minimizing hemodynamic fluctuations.

Improvement of activated sludge dewaterability by humus soil induced bioflocculation.

Effects of humus soil particles on the dewaterability of activated sludge were investigated. Cations leaching increased proportionally with the dosage of humus soil, and the leaching was not significant after 2 h. Divalent cations, Ca2+ and Mg2+, leaching from the humus soil played an important role in improving dewaterability of the biological sludge. On the contrary, dewaterability was not affected or slightly deteriorated by the monovalent cations, K+ and Na+ leached from the humus soil. Improvement in dewaterability of the sludge by addition of humus soil was higher than that of equivalent cations mixture. It seemed that the decrease of supracolloidal bio-particles (1 to 100 microm in diameter) resulted in diminishing of the blinding effect on cake and filter medium. SRF (specific resistance to filtration) of the humus soil added sludge varied in parallel with the M/D (monovalent to divalent cation) ratio, and the M/D ratio could be utilized as a useful tool for evaluation of the sludge dewatering characteristics. Long-term effects of humus soil on the improvement of activated sludge dewaterability were clearly identified by continuous operation results of a bench-scale MLE (Modified Ludzack Ettinger) system combined with a humus soil contactor. On the other hand, dewaterability of the control sludge was only slightly improved by a decrease in M/D ratio of the wastewater influent.