Biological Oxidation Research Articles

Fe(OH)3 induced the Anammox system to perform extracellular electron transfer for enhancement of NH4+ removal

It is widely found that the ratio of nitrite consumption to ammonia consumption (ΔNO2--N/ΔNH4+-N) in Anammox systems is lower than its stoichiometry of 1.32, but the reason is unclear. In this study, ΔNO2--N/ΔNH4+-N of an Anammox system decreased to 0.80 with the addition of Fe(OH)3, which was significantly lower than a control system without the addition of Fe(OH)3. The lower ratio or more NH4+ removal was likely related to the reduction of Fe(OH)3 that served as extracellular electron acceptor to anaerobically oxidize NH4+, namely Feammox. Chemical or biological oxidation of the produced Fe2+ formed the Fe(III)/Fe(II) cycle to likely cause the continuous Feammox in the Anammox system. Isotopic analysis verified that the Anammox sludge collected from the Fe(OH)3-added reactor produced more 30N2 by Feammox. Raman analysis showed that the outer membrane cytochrome c of Fe(OH)3-added Anammox sludge could participate in the extracellular electron transfer during Feammox. Metagenomic analysis further confirmed that the gene encoding redox enzymes of cytochrome c of Candidatus Brocadia were enriched with adding Fe(OH)3. The results suggested that the Fe(OH)3 induced Anammox bacteria to perform extracellular electron transfer, allowing the Anammox system to effectively remove NH4+ via the Feammox pathway.

Exploring Effective Bio-Cover Materials for Mitigating Methane Emission at a Tropical Landfill

Methane emission and oxidation in different bio-cover materials, i.e., sandy loam, compost, and stabilized wastes, were investigated at a municipal solid waste landfill in Thailand. The bio-cover was purged with extracted landfill gas while methane reduction through biological oxidation was studied. The moisture content in bio-cover materials was maintained with natural rainwater during the wet period and leachate irrigation during the dry period. Methane emissions were found to vary between media and were influenced by rainfall. The methane loading rates of the bio-cover varied from 8.2–20.3 mol/m3/d, being higher during the dry period. Methane removal rates at the bottom part of the biofilter (0.4–0.6 m depth), the most active zone, were found to be from 6.4–10.9 and 7.8–11.4 mol/m3/d during wet and dry periods. The highest methane removals were found in the lower part of sandy loam, followed sequentially by compost and stabilized wastes. Nevertheless, compost had the highest methane oxidation capacities and greater methanotroph population compared to sandy loam and stabilized wastes. Methanotroph type I was found to predominate during the dry period, whereas methanotroph type II was predominant during the wet period.

The Source, Harm and Treatment of Endocrine Disruptors in Groundwater

As a new class of pollutants, endocrine disruptors were widely distributed in environmental media such as air, soil, surface water and groundwater, which could interfere with the endocrine system of living organisms, had gradually become a major global issue and caused the world's universal concern. Groundwater was an important “Source” and “Sink” of EDCs, which could accumulate EDCs continuously and pose a great threat to human health and ecosystem. Therefore, the detection methods of EDCs in groundwater were summarized from two stages of pretreatment and analysis test, and the sources of EDCs in groundwater were analyzed from two aspects of endogenous and exogenous, the content distribution of EDCs in groundwater in some areas of our country were sum up, the harm of EDCs in groundwater was probed into from two angles of human health and ecosystem, and the treatment methods of EDCs in groundwater, such as physical chemistry method, biological treatment method and advanced oxidation method, were mainly introduced. Finally, the research problems and future development directions of EDCs in groundwater in our country were summarized and prospected respectively, in order to provide a reference for the prevention and control of groundwater EDCs pollution in our country.

Transformation of microplastics by oxidative water and wastewater treatment processes: A critical review.

Microplastics (MPs) are contaminants of emerging concern that accumulate in various environments, where they pose threats to both the ecosystem and public health. Since MPs have been detected in drinking water resources and wastewater effluents, more efficient treatment is needed at wastewater treatment plants (WWTPs) and drinking water treatment plants (DWTPs). This review discusses the potential of biological, photochemical, Fenton (-like) systems, ozonation, and other oxidation processes in the treatment of MPs in terms of their indicators of oxidation such as mass loss and surface oxidation. The oxidation processes were further analyzed in terms of limitations and environmental implications. Most previous studies examining MPs degradation using conventional treatments-such as UV disinfection, ozonation, and chlorination-employed significantly higher doses than the common doses applied in DWTPs and WWTPs. Owing to such dose gaps, the oxidative transformation of MPs observed in many previous studies are not likely to occur under practical conditions. Some novel oxidation processes showed promising MPs treatment efficiencies, while many of them have not yet been applied on a larger scale due to high costs and the lack of extensive basic research. Health and environmental impacts related to the discharge of oxidized MPs in effluents should be considered carefully in different aspects: the role as vectors of external pollutants, release of organic compounds (including organic byproducts from oxidation) and fragmentation into smaller particles as MPs circulate in the ecosystem as well as the possibility of bioaccumulation. Future research should also focus on ways to incorporate developed oxidation processes in DWTPs and WWTPs to mitigate MPs contamination.

Modified W, Ti-doped IrO2 anode for efficient organic contaminant oxidation in livestock wastewater

The treatment of livestock wastewater is a major environmental challenge due to the presence of antibiotics from animal excreta, which may pass through conventional biological oxidation treatment and pose a threat to public health. Electro-oxidation method presents an opportunity to remove antibiotics in the livestock wastewater at the source of generation, and titanium-based IrO2 anode has been shown to have excellent electro-catalytic activity and stability. However, the soaring price of iridium limits the practical application. In this work, we showed that W, Ti-doped IrO2 anodes largely preserved the electro-catalytic activity while reducing the cost of electrode fabrication. The prepared Ti/Sb-SnO2/(Ir0.6W0.2Ti0.2)Ox anode was shown to achieve 94 % conversion of sulfadiazine in 1 min and 100 % conversion in 15 min. Additionally, complete removal of chemical oxygen demand (COD0 = 700–800 mg/L) was achieved in 1–3 h of electrolysis at 40 mA/cm2. Chlorine-mediated oxidation was demonstrated to be the main mechanism for organic contaminant degradation. The COD removal during galvanostatic electrolysis exhibited zero-order kinetics, indicating that the reaction rate was controlled by the heterogeneous reaction at the anode surface. In the stability test, >95 % COD removal was maintained after 5 cycles of electro-oxidation experiments. The accelerated life of the anode was tested to be 352 h (1000 mA/cm2, 1 M H2SO4 electrolyte, 60 °C).

A developing novel alternative bio-oxidation approach to treat low-grade refractory sulfide ores at circumneutral pH

The extensive neutralization required in acidic bio-oxidation, a conventional pretreatment for low-grade refractory matrices in the gold industry, constitutes one of the principal drawbacks due to the large volume of waste streams. Performing an oxidative pretreatment at circumneutral pH with an in-situ neutralization would avoid the production of undesirable waste, causing potential economic and environmental advantages. For the first time, this investigation evaluates a novel process involving a biological oxidative pretreatment for low-grade refractory ore using two biosafety level 1 neutrophilic microorganisms encompassing Thiobacillus thioparus and Starkeya novella at near-neutral pH. Optimal bacterial growth conditions were determined regarding the culture medium and initial energy source using UV-visible and manual cell counting (cells/mL). Thereafter, biological oxidation of different matrices, including first elemental sulfur and subsequently a refractory sulfidic ore, was evaluated in batch flask cultures and then scaled up into a bioreactor using optimal experimental conditions. Results revealed that culture media containing ca. 4.5 and ca. 0.9 g/L thiosulfate favored biological oxidation of the refractory sulfidic ore using T. Thioparus and S. Novella, respectively, which led to corresponding sulfide oxidation of 27 and 14% within 10 days, comparable to reported studies. The biological action was confirmed by C/S detector and SEM technique of pre- and post-pretreatment residues. Overall, this research is a step forward to advance the understanding of a biological pretreatment out of the highly acidic pH range, promoting the view of a net-zero target by potentially reducing the production of more significant waste streams compared to conventional operations.

Impact of biochar amendment on antibiotic removal and ARGs accumulation in constructed wetlands for low C/N wastewater treatment

Constructed wetlands (CWs) amended with biochar to stimulate antibiotic and antibiotic resistance genes (ARGs) removal from carbon restricts wastewater holds particular application prospect due to high efficiency and good stability. In this study, we conducted biochar amended constructed wetland (BCW) and non-biochar amended constructed wetland (NCW) to explore the feasibility and mechanisms for sulfamethoxazole (SMX) and ARGs removal from low C/N wastewater. Results showed that biochar-amended considerably stimulated the biological oxidation and reduction process in CW, as evidenced by higher chemical oxygen demand (COD), nitrogen, and SMX removal performance (7.1 ± 2.6 %, 19.8 ± 3.6 %, 36.8 ± 6.2 %) than that in NCW. The accumulation of ARGs was negatively associated with SMX removal efficiency, where the int and sul genes performed lower concentration in BCW due to the higher SMX removal efficiency. The biochar’s dissolved organic carbon release in CWs indicated that water and alkaline media portray the optimum conditions for SMX and ARGs removal. Microbial community analysis exposed that more functional consortia capable of SMX metabolism (e.g., Arthrobacter, Ramlibacter, Flavobacterium, and norank_f_JG30-KF-CM45) were enriched in BCW. This study demonstrated the feasibility and mechanism of biochar-amended CWs for regulated SMX removal and ARGs accumulation, which provides new insights for enhancing the depuration ability of CWs.

Reductive dehalogenation pathways and inhibition mechanisms of 2,5-dichloronitrobenzene in UV/sulfite advanced reduction process

2,5 − dichloronitrobenzene (2,5 − DCNB) and its chlorine − containing intermediates as adsorbable organic halogens (AOX), which may cause persist environment and health damages, are widely present in fine chemical wastewater. However, AOX in high − salt wastewater are hardly removed by biological process and advanced oxidation process (AOPs). Advanced reduction processes (ARPs), especially UV/sulfite process, have attracted increasing attention in past few years due to their powerful reduction potential to refractory contaminants. In this study, the kinetics, main inhibition mechanisms, and degradation pathways of 2,5 − DCNB in UV/sulfite process were studied. The apparent reaction rate (kobs) increasing from 0.0059 min−1 to 0.0628 min−1 with sulfite dosage increasing from 2.6 mM to 104.2 mM and from 0.0027 min−1 to 0.0659 min−1 with pH value increasing from 3 to 12. Relative quantitation method based on EPR was developed to prove the dominant role of hydrated electron (eaq−) in UV/sulfite ARPs. A new sulfite activating pathway in dark was discovered at lower pH, which partly inhibits the ARPs. The nonlinear increase of kobs with increasing sulfite dosage was attributed to UV scattering which is caused by density fluctuation. The inhibition of Cl− triggered by ●OH from H2O direct photolysis by UV at 185 nm from lower pressure mercury lamp. This inhibition is linearly depending on Cl− concentration. The multiple competitive inhibition of NO3− was discussed and the three pathways are “inner filter” effect, eaq− competition and oxidizing species generation. In addition, the reduction pathways of 2,5 − DCNB during UV/sulfite ARPs were predicted by intermediates identification and density functional theory (DFT) calculation. Cyclohexanol with lower toxicity was identified as final product of UV/sulfite process. This study revealed the capacity of UV/sulfite ARPs for direct dehalogenation on benzene ring and the application potential in industrial wastewater dehalogenation.

Enhancing the Biological Oxidation of H2S in a Sewer Pipe with Highly Conductive Concrete and Electricity-Producing Bacteria.

Hydrogen sulfide (H2S) generated in sewer systems is problematic to public health and the environment, owing to its corrosive consequences, odor concerns, and poison control issues. In a previous work, conductive concrete, based on amorphous carbon with a mechanism that operates as a microbial fuel cell was investigated. The objective of the present study is to develop additional materials for highly conductive concrete, to mitigate the concentration of H2S in sewer pipes. Adsorption experiments were conducted to elucidate the role of the H2S reduction. Additionally, electricity-producing bacteria (EPB), isolated from a municipal wastewater treatment plant, were inoculated to improve the H2S reduction. The experimental results showed that inoculation with EPB could decrease the concentration of H2S, indicating that H2S was biologically oxidized by EPB. Several types of new materials containing acetylene black, or magnetite were discovered for use as conductive concrete, and their abilities to enhance the biological oxidation of H2S were evaluated. These conductive concretes were more effective than the commercial conductive concrete, based on amorphous carbon, in decreasing the H2S concentration in sewer pipes.

A mitochondrion targetable dimethylphosphorothionate-based far-red and colorimetric fluorescent probe with large Stokes shift for monitoring peroxynitrite in living cells.

Peroxynitrite (ONOO-) is a biological oxidant that is related to numerous physiological and pathological processes. An overdose of ONOO- is the cause of various serious diseases. Some evidence demonstrates that mitochondria are the major sites of ONOO- production. Therefore, monitoring mitochondrial ONOO- is important to understand the related pathological processes in living systems. Herein, a colorimetric and far-red fluorescent sensing probe (PCPA) for the determination of ONOO- was constructed based on a dicyanoisophorone skeleton using dimethylphosphorothionate as the recognition group and pyridine salt as the mitochondrion-targeting unit. PCPA showed a far-red fluorescence response to ONOO- accompanied by a distinct color change from colorless to yellow via the ONOO- induced deprotection of dimethylphosphorothionate. In addition, PCPA exhibited a large Stokes shift (200 nm), high selectivity detection and high sensibility (LOD = 39 nM). Furthermore, PCPA was successfully employed for imaging ONOO- and tracing ONOO- in mitochondria. PCPA presents a new recognition group and has potential applications in the biology field.

Study of effect of beetroot juice in muscle damage recovery during anaerobic exercise with reference to unani system of medicine

The purpose of this review is to evaluate the effect of beetroot juice in muscle damage recovery during anaerobic exercise in unani medicine because unani medicine claims that beetroot juice is Muhalil-e-waram and the term Muhalil-e-waram means to reduce the inflammation and to reduce the swelling. And according to modern science, beetroot juice is antioxidant and anti- inflammatory food because it has a high NO3- content. NO3- can be reduced to nitrite via bacteria in oral cavity and by special enzymes (Ex-Xanthine oxide) within tissues.There are several pathways to metabolize nitrite to Nitric oxide (NO) and other biological active nitrogen oxide. NO is signaling molecule formed in the endothelium by the enzyme endothelium NO synthase which triggers the vasculature to relax (vasodilatation) by interacting with vascular smooth muscle leading to increase blood flow. NO facilitates increased blood flow at rest and during exercise and hence it reduces inflammation and helps in improving muscle damage recovery in short time duration.

Study on purification method of micro-polluted groundwater

The infiltration of surface water makes the groundwater with only iron, manganese and heavy metal elements exceeding the standard be invaded by ammonia nitrogen, nitrate and organic matter, forming compound pollution groundwater, which has attracted extensive attention of scholars at home and abroad. This paper introduces the source and harm of micro-pollutants in groundwater, and expounds the research progress of biological method, adsorption method and contact oxidation method to treat micro-polluted groundwater, which lays a foundation for the selection of micro-polluted groundwater treatment methods.

Enhanced PMS/O2 activation by self-crosslinked amine-gluteraldehyde/chitosan-Cu biocomposites for efficient degradation of HEPES as biological pollutants and selective allylic oxidation of cyclohexene

Optimization and mechanism elucidation of the catalytic degradation of HEPES and selective aerobic oxidation of cyclohexene by Cu@cross-linked magnetic chitosan.

ОСОБЕННОСТИ РАСЧЕТА ВЕЛИЧИНЫ ФАКТОРА ОБНОВЛЕНИЯ ПОВЕРХНОСТИ ПУЗЫРЬКОВ ВОЗДУХА

The resource intensity of biological wastewater treatment is reduced by increasing the energy efficiency of the pneumatic aeration systems used in the aeration tank. Modernisation of the aeration process is possible with the development of an adequate mathematical model describing the process of mass transfer from air bubble to water the oxygen required for biological oxidation of wastewater pollutants. The analysis of the Lewis- Whitman two-film theory, Higbee's penetration theory, and P. W. Dankwerts' theory of deformed bubble surface renewal describing the process of mass transfer of air oxygen into water showed the peculiarities of their application to gas-liquid systems. The factor of renewal of deformed surface of air bubbles is of great importance for describing the processes of mass transfer of air oxygen to water when using pneumatic aeration system in aeration tanks. In turbulent flow at continuous renewal of interfacial surface created by air bubbles, there is intensification of mass transfer process due to turbulent diffusion, which is reflected in calculated mathematical dependences. The use of mathematical dependences determining the rate of mass transfer of air oxygen to water through the deformable surface of bubbles formed in the aeration volume of the aeration tank will make it possible to take into account the change in their shape. This will increase the accuracy of determining the values of technological characteristics of pneumatic aeration systems.

Bacteria in the biosynthesis of animal nutrition components for crews of autonomous transport systems

The International Space Station (ISS) is currently using a water electrolysis process to produce oxygen. The hydrogen produced as a by-product is removed overboard. Carbon dioxide from crew breathing, dissolved in the atmosphere of the station, are extracted and also removed outside the station, but NASA expects to use it and convert it by the physicochemical reaction Sabatier in methane and water. Water will be used for crew needs and electrolysis, and methane is also planned to be removed overboard. When these interrelated processes work, very important substances are lost: methane, carbon dioxide, and hydrogen. This situation can be remedied by including in the life support system (LSS) of the ATS closed biotechnological regeneration cycles operating in a waste-free mode and synergistically solving the problems of complex provision of the crew with oxygen, water, and, most importantly, food. The process of biological oxidation of methane by methanotrophs bacteria is observed in nature in the first link of the food chain of the world's ocean and has long been used in terrestrial conditions for the industrial production of animal biomass for food and feed purposes. The same can be said about the use of hydrogen bacteria, which use carbon dioxide as a carbon source, with hydrogen as their energy source. Tolerance of these cultures to common nutrient media and the same technological parameters of biosynthesis allows their joint cultivation to obtain animal ingredients for crew food. The proposed work is devoted to the study of alternative processes, integrated use of carbon dioxide, methane, and hydrogen in LSS ATS.

Highly sensitive and rapid detection of hypochlorous acid in aqueous media and its bioimaging in live cells and zebrafish using an ESIPT-driven mycophenolic acid-based fluorescent probe.

Excessive production of potent biological oxidants such as HOCl has been implicated in numerous diseases. Thus, it is crucial to develop highly specific and precise methods to detect HOCl in living systems, preferably with molecules that can show a distinct therapeutic effect. Our study introduces the synthesis and application of a highly sensitive fluorescence "turn-on" probe, Myco-OCl, based on the mycophenolic acid scaffold with exceptional water solubility. The ESIPT-driven mechanism enables Myco-OCl to specifically and rapidly detect (<5 s) HOCl with an impressive Stokes shift of 105 nm (λex = 417 nm, λem = 522 nm) and a sub-nanomolar (97.3 nM) detection limit with the detection range of 0 to 50 μM. The potential of Myco-OCl as an excellent biosensor is evident from its successful application for live cell imaging of exogenous and endogenous HOCl. In addition, Myco-OCl enabled us to detect HOCl in a zebrafish inflammatory animal model. These underscore the great potential of Myco-OCl for detecting HOCl in diverse physiological systems. Our findings thus offer a highly promising tool for detecting HOCl in living organisms.

Analysis of the development and effects of a combined treatment system for acid mine drainage via bio-oxidation and carbonate rock neutralization

A unique acid mine drainage treatment system for simultaneous biological oxidation and carbonate neutralization was designed for use prior to the carbonate rock neutralization process.

English

A co-flow pilot filter with a packing support material (coated jujube seeds) was constructed and tested for the biological removal of iron from Senegalese groundwater. Indeed, it is a PVC tube with an internal diameter of 40 mm and a height of 90 cm. The performance of the filter was tested at a constant hydraulic head of 261.67 m3/m2 per day while the iron feed concentrations varied between 0.5-1, 0.5-1.5 and 0.5-2 mg/L, respectively. Coated jujube seeds, covered with a plastic layer and a biofilm containing microorganisms, were used as the filter material. The iron removal was carried out in a single stage, for which a period of two months was required for the maturation of the bed. In optimal working conditions (QL = 8.11 L/h; pH = 9.5; [Fe2+]0 = 2 mg/L; P = 1.013 bar and T = 25&plusmn;1&deg; C; Redox potential = 300 mV), an operating cycle time of 1 day has proven to be sufficient for the filter bed backwash operation. The results show that the biological treatment gives reduction percentages of 39.3, 48.76 and 67.23%, respectively for the boreholes of Pout Kir&egrave;ne (PK2), Pout Sud (PS5) and Koungheul (KK5). &nbsp; Key words:&nbsp; Biofilm, continuous test, biological oxidation, iron removal, column, doped water.

Determination of Sugars, Amino Acids, pH and Alcohol in Bamboo Beverage from Southern Highlands, Tanzania

The amounts of sugars and amino acids play significant roles in defining the fermentation process and quantifying the alcohol levels in beverages, while pH affects the biological stability, colour, oxidation rate, and protein stability of alcoholic beverages. This study investigated the sugar content, amino acids, alcohol levels, and pH of bamboo beverage from Tanzania's southern highlands. During storage, the sugars significantly decreased (p &lt; 0.05), especially when kept at room temperature from 52.96 to 0.00 (source 1), 53.35 to 0.00 (source 2) and 53.57 to 0.00 (source 3) g/L for fructose, from 47.93 to 14.78 (source 1), 47.23 to 14.91 (source 2) and 47.61 to 14.77 (source 3) g/L for glucose, and from 0.40 to 0.00 (source 1), 0.36 to 0.00 (source 2) and 0.37 to 0.00 (source 3) g/L for sucrose after six days of storage. A total of 15 amino acids were determined from the bamboo beverage with tyrosine being the most prevalent (597.68 mg/L for source 1, 599.44 mg/L for source 2 and 597.83 mg/L for source 3), followed by valine (261.13 mg/L for source 1, 261.24 mg/L for source 2 and 262.54 mg/L for source 3), threonine (76.69 mg/L for source 1, 76.91 mg/L for source 2 and 77.13 mg/L for source 3), and serine (66.37 mg/L for source 1, 67.23 mg/L for source 2 and 66.68 mg/L for source 3). After six days of storage at room temperature, there was a significant decrease in pH from 4.04 to 3.63. Alcohol content ranged from 3.11 to 9.05% v/v at the room temperature storage. These results might facilitate the optimal use of bamboo beverages, which have been neglected due to lack of scientific information such as amino acid and sugar levels.&#x0D; Keywords: Bamboo beverage, ulanzi, amino acids, sugars, alcohol content

Elevated atmospheric CO2 concentration changes the eco-physiological response of barley to polystyrene nanoplastics

The impacts of plastic particles are being extensively studied, especially in agro-ecosystem. In the simulating experiment, elevated atmospheric CO2 concentration (e[CO2], 800 μmol mol−1) increased nanoplastics (NPs, red fluorescently labeled polystyrene, 95 nm) concentration in NPs-treated roots from 0.0082 mg g−1 to 0.0275 mg g−1. The H2O2 concentrations in NPs-treated leaves and roots were decreased by 28.41 % and 43.29 % responding to e[CO2], due to the intervention of antioxidant enzymes. In NPs-treated plants, e[CO2] increased Pn, Ci and carotenoid concentration by 10.97 %, 118.07 % and 40.83 %, while decreased gs and Tr by 36.36 % and 32.55 %. e[CO2] weakened NPs-induced modulation of photosynthetic light reaction via causing less electron production, but induced higher Ci promoting the Calvin-Benson cycle in NPs-treated plants. In the presence of NPs exposure, e[CO2] aggravated the reduction in glycolysis by decreasing the activities of cytInv, vacInv, cwInv, AGPase, UGPase, PGM, PGI, G6PDH, PFK and Ald, while suppressed the efficiency of tricarboxylic acid and biological oxidation due to the decreased activities of CS, ICDH, α-KGDH, NADH dehydrogenase, succinate dehydrogenase, cytochrome c oxidase and ATP synthase. The results showed the landscapes by which e[CO2] sculpt the eco-physiological response of barley plant to NPs, and provided key insights into the agricultural sustainability in the future under emerging pollution and environmental changes.