Biological Oxidation Research Articles

Using molecular weight-based fluorescent detector to characterize dissolved effluent organic matter in oxidation ditch with algae.

Implementation of microalgae has been considered for enhancing effluent wastewater quality. However, it can cause environmental issues due to the release of extracellular and algal organic matter in the biological process. This study aimed to investigate the characteristics of dissolved effluent as algae- and bacteria-derived organic matter during the oxidation ditch process. Furthermore, experiments were conducted under three combinations filled by Spirulina platensis, Chlorella vulgaris, and without microalgae. The results showed that dissolved effluent organic matter was more aromatic and hydrophobic than before treatment. Fluorescence spectroscopy identified two components-aromatic protein-like and soluble microbial product-like components-at excitation/emission of 230/345nm and 320/345nm after treatment, instead of fulvic acid-like at 230/420nm and humic acid-like at 320/420nm in raw wastewater. These components were fractionated based on the average of molecular weight cut-offs (MWCOs), and high (MWCOs > 50,000Da), medium (MWCOs 50,000-1650Da), and low molecular weights (MWCOs < 1650Da) were reported. Biological oxidation ditch under symbiosis algal bacteria generated humic and fulvic acid with a higher MWCOs than the process without algal. The quality and quantity of dissolved effluent organic matter in an oxidation ditch reactor were significantly affected by algal-bacteria symbiotic.

Biological contact oxidation and an artificial floating island for black odorous river purification

Abstract Due to destruction caused by urbanization and anthropogenic activities, various methods for treating black odorous rivers have been proposed. Herein, a treatment scheme was put forward for a black odorous river in Dongguan City, Guangdong Province. The river was treated using composite artificial floating island and improved biological contact oxidation processes as the core, supplemented by source control, substrate purification, and water ecosystem construction. The transparency, dissolved oxygen, ammonia nitrogen (NH3-N), and total phosphorus (TP) of the water body met the China Surface Water Environmental Quality Standard (GB3838-2002) V. The oxidation–reduction potential was remarkably improved and the black odor phenomenon was eliminated. The composite artificial floating island had the highest TP removal rate of 38.30%, while the improved biological contact oxidation process had the highest NH3-N removal rate of 43.08%. The process is effective in improving the quality of black odorous rivers and has high applicability; thus, the process provides a reference for the treatment of other black odorous water bodies.

Research Progress on Integrated Treatment Technologies of Rural Domestic Sewage: A Review

The improvement of rural living standards in developing countries and the continuous upgrading of the rural industrial economy have prompted the diversification of rural areas and residential forms. Thus, an integrated rural sewage treatment process has gradually become the mainstream technology for rural sewage treatment. Numerous studies have reported the effects of ecological wastewater treatment. Meanwhile, the relevant process technologies, evaluations, and operating models of the integrated rural sewage treatment process have yet to be thoroughly summarized. This review aims to fill these gaps. First, the applicability of artificial wetland, soil infiltration, stabilization pond, and integrated rural sewage treatment process technology in rural sewage treatment are outlined and compared. Second, the process flow, technical characteristics, and economic indicators of typical integrated sewage treatment processes (i.e., Anoxic/Oxic (A/O) process, Membrane Bio-Reactor (MBR) process, biological contact oxidation process, Sequencing Batch Reactor Activated Sludge (SBR) process) are introduced. The engineering application effects of the integrated rural sewage treatment process in different countries are also described. Third, the practical and effective evaluation methods of the integrated rural sewage treatment process are introduced. Bearing in mind the current operation and maintenance management modes of the integrated rural sewage treatment process in developed and developing countries, combined with the national conditions of developing countries, the prospect section provides development proposals for further optimization and improvement of the integrated rural sewage treatment process in developing countries.

Deciphering the Inhibition of Ethane on Anaerobic Ammonium Oxidation.

Anaerobic ammonium oxidation (anammox) and nitrification, two common biological ammonium oxidation pathways, are critical for the microbial nitrogen cycle. Short chain alkanes (C2-C8) have been well-known as inhibitors for nitrification through interaction with the ammonia monooxygenase, while whether these alkanes affect anammox is an open question. Here, this work demonstrated significant inhibition of ethane on anammox and revealed the inhibitory mechanism. The acute inhibition of ethane on anammox was concentration-dependent and reversible; 0.86 mM dissolved ethane caused 50% inhibition (IC50), and 1.72 mM ethane almost completely inhibited anammox. After long-term exposure to 0.09 mM ethane for 30 days, the ammonium (nitrite) removal rate dropped from 202 (267) mg N L-1 d-1 to 1 (1) mg N L-1 d-1, and the abundance of anammox bacteria decreased from 61.9% to 9.5%. The intercellular ammonium concentration of anammox bacteria decreased after ethane exposure, while metatranscriptome analysis showed significant upregulation of genes for ammonium transport of anammox bacteria. Thus, ethane could suppress ammonium uptake resulting in the inhibition of anammox activities. As ethane is the second most prevalent alkane after methane in various anoxic environments, ethane may have an important effect on the nitrogen cycle driven by anammox that should be investigated in future research.

Bio-enhanced contact oxidation process using a heterotrophic nitrifying-aerobic denitrifying strain

The intention of this study was to explore whether it is feasible to use a heterotrophic nitrifying-aerobic denitrifying strain to bio-enhance the biological contact oxidation process. In this experiment, Acinetobacter sp. RW, a highly efficient heterotrophic nitrifying-aerobic denitrifying strain isolated in the laboratory, was used as the functional strain. The results show that part of the NH4 +-N (ammonia nitrogen), TN (total nitrogen) and CODCr (dichromate oxidizability) of the sewage could be effectively removed via the biological contact oxidation process performed in the laboratory. Average removal ratios of NH4 +-N, TN and CODCr increased by 32.8%, 4.33% and 11.13%, respectively, after biological enhancement of RW. According to the biodiversity information, Acinetobacter exhibited the greatest change at the genus level in both the water and biofilm after adding the strain RW. In the 12 days without RW addition, the treatment efficiency of the device was only 1.01% different from that during daily dosing. The results demonstrate that the treatment efficiency of the process can be improved by adding RW. RW can effectively adhere to the biofilm and become one of the dominant strains. Therefore, we conclude that the biological contact oxidation process bio-enhanced by RW was successful and has practical potential.

The evolution of dissolved inorganic carbon (DIC) and δ13CDIC in acid mine drainage polluted karst rivers: Preliminary findings from laboratory experiments

Acid mine drainage (AMD) has caused serious pollution in the surface water environments of karst areas, but the effect of AMD on the dissolved inorganic carbon (DIC) dynamics in the receiving karst rivers remains poorly understood. The AMD and karst river water were sampled from the Yangliujie River watershed in Southwest China, and mixed different proportions of AMD and karst river water in a laboratory experiment to simulate seasonal hydrological conditions in the river, in an attempt to explore the impact of AMD on the loss rate and evolution of DIC in karst river water. The results showed that AMD can cause a rapid pH drop in karst river water, resulting in approximately 41.0 ± 11.8 % DIC loss in the early stage of mixing as CO2(g) release to the atmosphere. With the biological or chemical oxidation of Fe2+, and followed by Fe3+ biogenic formation of schwertmannite or hydrolysis, the pH decreased and the DIC concentration further decreased in the mixed samples, the degree of decrease was related to the oxidation rate of Fe2+. With decreasing DIC concentration, δ13CDIC enrichment gradually increased. When the mixing ratio of AMD was large, the total H+ in AMD and H+ generated by the oxidation of Fe2+ exceeded the HCO3− content in karst river water, the isotopic enrichment coefficient caused by the initial mixing and the end of the reaction was small, and the DIC transformation was mainly dominated by the loss of CO2(g). When a small proportion of AMD was mixed in, the HCO3− concentration in the mixed water sample was in excess of the H+ produced by Fe2+ and the total H+ in AMD, the isotopic enrichment coefficient caused by the initial mixing and the end of the reaction was larger, and the DIC conversion was mainly affected by HCO3− dehydration. These preliminary findings support evidence showing DIC conversion and loss in AMD-affected karst rivers increase the transfer of carbon dioxide to the atmosphere, which diminishes net carbon sink fluxes in karst river basins, so reasonable AMD treatment methods should be applied to minimize these negative impacts.

Transcriptome analysis reveals manganese tolerance mechanisms in a novel native bacterium of Bacillus altitudinis strain HM-12

Bacillus altitudinis HM-12, isolated from ferromanganese ore tailings, can resist up to 1200 mM Mn(II) when exposed to concentrations from 50 mM to 1400 mM. HM-12 exhibited high Mn(II) removal efficiency (90.6 %). We report the transcriptional profile of HM-12 using RNA-Seq and found 423 upregulated and 536 downregulated differentially expressed genes (DEGs) compared to the control. Gene Ontology analysis showed that DEGs were mainly linked with transporter activity, binding, catalytic activity in molecular function, cellular anatomical entity in cellular component, cellular process, and metabolic process. Kyoto Encyclopedia of Genes and Genomes analysis showed that DEGs were mostly mapped to membrane transport, signal transduction, carbohydrate and amino acid metabolism, energy metabolism, and cellular community pathways. Transport analysis showed that two manganese importer systems, mntH and mntABC, were significantly downregulated. The manganese efflux genes (mneS, yceF and ykoY) exhibited significant upregulation. Manganese homeostasis seems to be subtly regulated by manganese uptake and efflux genes. Moreover, it was found that copA as a Mn(II) oxidase gene and a copper chaperone gene copZ were considerably upregulated by signal transduction analysis. csoR encoding a transcriptional repressor which can regulate the copZA operon was upregulated. The strong Mn(II) oxidizing activity of HM-12 was also confirmed by physicochemical characterization. In metabolism and environmental information processing, yjqC encoding manganese catalase was significantly upregulated, while katE and katX encoding heme catalases were significantly downregulated. The antioxidant gene pcaC was significantly upregulated, but ykuU encoding alkyl hydroperoxide reductase, yojM encoding superoxide dismutase, and perR encoding redox-sensing transcriptional repressor were downregulated. These results highlight the oxidative activity of HM-12 by regulating the transcription of oxidase, catalase, peroxidase, and superoxide dismutase to sense the cellular redox status and prevent Mn(II) intoxication. This study provides relevant information on the biological tolerance and oxidation mechanisms in response to Mn(II) stress.

Hematite-promoted nitrate-reducing Fe(II) oxidation by Acidovorax sp. strain BoFeN1: Roles of mineral catalysis and cell encrustation.

Although nitrate-reducing Fe(II) oxidizing (NRFO) bacteria can grow sustainably in natural environments, numerous laboratory studies suggested that cell encrustation-induced metabolism limitations and cell death occurred more seriously in the absence of natural minerals. Hence, a study on how natural minerals could affect NRFO is warranted. This study examined the impact of hematite on NRFO by Acidovorax sp. BoFeN1 with different electron donors (acetate and Fe(II), acetate alone, and Fe(II) alone) and with nitrate as an electron acceptor. When acetate and Fe(II) were used as the electron donors, the amount of Fe(II) oxidation and nitrate reduction was enhanced in the presence of hematite, whereas no promotion was observed when only acetate was added as an electron donor. Under the conditions with only Fe(II) added as an electron donor, the level of Fe(II) oxidation was increased from 3.07 ± 0.06 to 3.92 ± 0.02 mM in the presence of hematite and nitrate reduction was enhanced. This suggests that hematite promotes microbial nitrate reduction by accelerating the biological oxidation of Fe(II). The main secondary minerals were goethite and lepidocrocite. After adding hematite, the assemblage of iron minerals on the cell surface decreased, and the cell crusts became thinner, indicating that hematite effectively mitigated cell encrustation. Furthermore, hematite accelerated the chemical oxidation of Fe(II) by nitrite. Hence, hematite can promote the NRFO of Acidovorax sp. BoFeN1 via two possible pathways: (i) hematite acts as nucleation sites to mitigate cell encrustation; (ii) hematite catalyzes the biological and chemical oxidation of Fe(II) through the mineral catalysis effects. This study highlights the importance of existing iron minerals on NRFO and sheds light on the survival strategy of NRFO bacteria in anoxic subsurface environments.

Transcriptomic Evidence That Switching from Tobacco to Electronic Cigarettes Does Not Reverse Damage to the Respiratory Epithelium.

The health benefits of switching from tobacco to electronic cigarettes (ECs) are neither confirmed nor well characterized. To address this problem, we used RNA-seq analysis to compare the nasal epithelium transcriptome from the following groups (n = 3 for each group): (1) former smokers who completely switched to second generation ECs for at least 6 months, (2) current tobacco cigarette smokers (CS), and (3) non-smokers (NS). Group three included one former cigarette smoker. The nasal epithelial biopsies from the EC users vs. NS had a higher number of differentially expressed genes (DEGs) than biopsies from the CS vs. NS and CS vs. EC sets (1817 DEGs total for the EC vs. NS, 407 DEGs for the CS vs. NS, and 116 DEGs for the CS vs. EC comparison). In the EC vs. NS comparison, enriched gene ontology terms for the downregulated DEGs included cilium assembly and organization, whereas gene ontologies for upregulated DEGs included immune response, keratinization, and NADPH oxidase. Similarly, ontologies for cilium movement were enriched in the downregulated DEGs for the CS vs. NS group. Reactome pathway analysis gave similar results and also identified keratinization and cornified envelope in the upregulated DEGs in the EC vs. NS comparison. In the CS vs. NS comparison, the enriched Reactome pathways for upregulated DEGs included biological oxidations and several metabolic processes. Regulator effects identified for the EC vs. NS comparison were inflammatory response, cell movement of phagocytes and degranulation of phagocytes. Disease Ontology Sematic Enrichment analysis identified lung disease, mouth disease, periodontal disease and pulmonary fibrosis in the EC vs. NS comparison. Squamous metaplasia associated markers, keratin 10, keratin 13 and involucrin, were increased in the EC vs. NS comparison. Our transcriptomic analysis showed that gene expression profiles associated with EC use are not equivalent to those from non-smokers. EC use may interfere with airway epithelium recovery by promoting increased oxidative stress, inhibition of ciliogenesis, and maintaining an inflammatory response. These transcriptomic alterations may contribute to the progression of diseases with chronic EC use.

LINC00963 May Be Associated with a Poor Prognosis in Patients with Cervical Cancer.

BackgroundRecently, the upregulation of LINC00963 expression has been reported in various cancer subtypes. LINC00963 expression can promote cancer cell invasion and metastasis. However, the clinical significance of LINC00963 in cervical and endocervical cancer (CESC) has remained relatively unexamined.Material/MethodsWe assessed the mRNA expression of LINC00963 in patients with CESC based on data acquired from The Cancer Genome Atlas (TCGA) to determine pathways involved in CESC pathogenesis with respect to LINC00963. We included 3 normal and 304 tumor samples in this study.ResultsThe scatter plot and paired plot showed differences in LINC00963 expression between normal and tumor samples (P<0.01). Overall survival (OS) analysis revealed that CESC patients with high expression of LINC00963 demonstrated worse prognosis than CESC patients with low expression of LINC00963 (P<0.01). Multivariate analysis with the Cox proportional hazards model indicated that the expression of LINC00963 (HR 0.297; 95% CI 0.115–0.776; P=0.012) and primary therapy outcome (HR 0.162; 95% CI 0.059–0.446; P=0.001) were independent prognostic factors for patients with CESC. GSEA results showed that reactome biological oxidations, inflammasomes, apoptosis, toll-like receptor signaling pathway, JAK/STAT signaling pathway, and NF-κB activation were differentially enriched in CESC samples with the high LINC00963 expression phenotype.ConclusionsOur results confirmed the association of significantly high levels of LINC00963 expression in CESC with several observed clinical features. LINC00963 may be a potentially useful prognostic molecular biomarker associated with poor survival in patients with CESC.

Combination of electrocoagulation with solar photo Fenton process for treatment of landfill leachate

ABSTRACT The aim of the present work was to provide a viable and active way to remove COD and colour from landfill leachate treated by adopting combined process of electrocoagulation and solar photo Fenton process. Coagulating agents such as metal hydroxides are created by the electrolysis process through self-sacrificial electrodes. Aluminium and iron dissolves at the anode and hydrogen gas are generated at the cathode when aluminium and iron electrodes are utilised. The contaminants interact with the coagulating agent to generate enormous organic flocs. The leachate was obtained from a landfill in Madurai and then it was characterised in terms of its major predominant pollutants. In this study, the electrocoagulation process was used in conjunction with the solar photo Fenton process to treat the leachate under ideal conditions of pH = 7, NaCl = 2 g/L, voltage = 4 V, Al & Fe electrodes and inter electrode distance = 3 cm with a COD and colour removal effectiveness of 75% and 76%, respectively. Furthermore, the effluent from the electrocoagulation process was treated using a solar photo Fenton process at pH = 3, H2O2 = 10 g/L and Fe2+ = 1 g/L with COD and colour reduction effectiveness of 90% and 91%, respectively. In this combination of treatment systems, leachate biodegradability increased from 0.35 to 0.73, favouring the biological oxidation process in conventional treatment plants. This research demonstrates that employing this paired electrocoagulation–solar photo Fenton to treat landfill leachate can achieve consistent treatment effects with high removal efficiencies, and that it is an acceptable treatment technique for landfill leachate.

Degradation of amoxicillin applying photo-Fenton and acid hydrolysis processes with toxicity evaluation via antimicrobial susceptibility tests

ABSTARCT The antibiotic amoxicillin (AMX) is a semisynthetic aminopenicillin, classified as an β-lactam antibiotic. This work aims to evaluate the AMX degradation (190 mg L–1), in aqueous medium, applying photo-Fenton ([TOC]0 = 100 mgC L−1; FH2O2 = 3.27 mmol min−1; [Fe2+] = 0.27 mmol L−1; pH = 3.0; T = 40°C) and acid hydrolysis processes. Along the experiments, samples were withdrawn and analyzed by a total organic carbon (TOC) analyzer and a liquid chromatography system coupled to diode array (HPLC-DAD) and mass spectrometry (HPLC-MS) detectors. The hydrolysis process proved to be less efficient, because AMX removals greater than 80% were observed only after 24 hours of reaction (pH 2). Conversely, the photo-Fenton process removed completely AMX in just 20 minutes, reaching 85% of TOC removal in 2 hours. Finally, the AMX aqueous solutions treated by the studied processes was also evaluated in respect of its toxicity to some microorganisms, applying two antimicrobial susceptibility tests: disk-diffusion and broth microdilution methods. It was observed that the AMX aqueous solutions, pretreated by the photo-Fenton process, for just 7.5 min of reaction time, did not inhibit the microorganisms growth. The obtained results show that the photo-Fenton process was able to degrade AMX, in a relatively short time, and that the generated degradation products did not inhibit the microorganisms growth, when compared to acid hydrolysis process. Thus, it was verified the potential application of the photo-Fenton system as a pretreatment step to conventional biological oxidation processes for the treatment of industrial wastewaters.

Integrated system for recycling and treatment of hazardous pharmaceutical wastewater

This study aimed to investigate an integrated system that can deal with different pharmaceutical wastewaters. Pharmaceutical wastewater was subjected to biological, chemical and advanced oxidation according to its pollutant’s nature. Wastewater with high total suspended solids (TSS 480 mg/L) was subjected to a conventional chemical treatment process utilizing different coagulants. The best results were obtained by using calcium oxide and alum added with calcium oxide where the removal efficiency of COD was 46.8% and 51%. Highly loaded pharmaceutical wastewater (COD 9700 mg/L, BOD/COD 0.16) had been subjected to Fenton oxidation, the removal of COD reached 80.4%, and the ratio of BOD/COD is enhanced to 0.6. Photocatalysis by using different nanomaterials was applied to pharmaceutical wastewater containing 10 mg/L of phenols. Phenol is completely removed by using mesoporous TiO2 after 90-min irradiation and after 120 min in the case of TiO2/P25 and TiO2/UV 100 nanocomposites, while it is removed by 40% in case of using mesoporous TiO2/Ta2O5. Effluent-treated water from previous routes was subjected to biological treatment and followed with disinfection by using UV as post-treatment. The final COD was 40, and it matches with the Egyptian practice code for water reuse in agriculture (ECP 501 in Egyptian code of practice for the use of treated municipal wastewater for agricultural purposes. The ministry of Housing Utilities and Urban Communities., n.d. No title, 2015). Results showed also using treated wastewater in irrigation of barley and bean seeds achieved germination ratio up to 71% in barely and 70% in bean compared with that irrigated with Nile water, which reached 70% and 75%, while it was about 16.6% and 30% in case of irrigation with untreated wastewater (Jeong et al. in Water (Switzerland). https://doi.org/10.3390/w8040169, 2016).

Detection and Treatment of Persistent Pollutants in Water: General Review of Pharmaceutical Products

AbstractEnvironmental problems of great complexity arise from the enormous number of toxic substances that are generated by anthropogenic activities. Seemingly, society encounters new issues every day thus these problems seem to be endless. Now in the face of the COVID‐19 pandemic and the SARS‐CoV‐2 crisis, a large number of emerging treatment compounds generated by pharmaceutical companies worldwide makes future issues even more treacherous. For this reason, there is an increasing need to detect and treat emerging compounds to prevent them from becoming persistent pollutants. This review describes the advances in the use of electrochemical sensors with modified carbon‐based electrodes among other issues, to determine antibiotics, anti‐inflammatories and antidepressants levels in the environment. It further explores technologies suggested for cleaning wastewater polluted by pharmaceutical products using biological or advanced oxidation processes including photolysis, photocatalysis, microwave heating, ultrasound, Fenton, electro‐Fenton, photoelectro‐Fenton and various combined treatments.

Enhanced adsorption and photocatalytic removal of PFOA from water by F-functionalized MOF with in-situ-growth TiO2: Regulation of electron density and bandgap

PFOA has caused enormous environmental risks with recalcitrance, toxicity, and bioaccumulation, while the degradation of PFOA is still a challenging topic related to the high energy of CF bonds. However, the conventional methods such as biological oxidation, electrochemical oxidation and membrane separation have their own drawbacks. Actually, adsorption-photocatalysis is considered a potential treatment due to effectiveness and thoroughness. Instead of preparing the composite material by adding TiO2, the method to in-situ grow TiO2 in the MOF (MIL-125(Ti)) was carried out, which achieved narrowed band gap and improved the photoresponse ability, simultaneously. Furthermore, the surface F-functionalized MOF provided more available special adsorption sites for PFOA enrichment. Linked fluorine groups not only improved the adsorption capacity (185.151 μmol/g) but also enhanced the photocatalytic rate (1.221 E−4/s) by altering the electronic density of VB and CB. The constructed F-TiO2@MIL-125 stepwise degraded PFOA through a dominant ·OH attack pathway and maintained the oxidize ability of h+ to PFOA. As a bifunctional material for adsorption and photocatalysis, F-TiO2@MIL-125 was able to be applied in various water environments repeatedly, which has unlimited environmental application potential.

Improving Nitrogen Use Efficiency in Aerobic Rice Based on Insights Into the Ecophysiology of Archaeal and Bacterial Ammonia Oxidizers.

The abundance and structural composition of nitrogen (N) transformation-related microbial communities under certain environmental conditions provide sufficient information about N cycle under different soil conditions. This study aims to explore the major challenge of low N use efficiency (NUE) and N dynamics in aerobic rice systems and reveal the agronomic-adjustive measures to increase NUE through insights into the ecophysiology of ammonia oxidizers. Water-saving practices, like alternate wetting and drying (AWD), dry direct seeded rice (DDSR), wet direct seeding, and saturated soil culture (SSC), have been evaluated in lowland rice; however, only few studies have been conducted on N dynamics in aerobic rice systems. Biological ammonia oxidation is majorly conducted by two types of microorganisms, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). This review focuses on how diversified are ammonia oxidizers (AOA and AOB), whose factors affect their activities and abundance under different soil conditions. It summarizes findings on pathways of N cycle, rationalize recent research on ammonia oxidizers in N-cycle, and thereby suggests adjustive agronomic measures to reduce N losses. This review also suggests that variations in soil properties significantly impact the structural composition and abundance of ammonia oxidizers. Nitrification inhibitors (NIs) especially nitrapyrin, reduce the nitrification rate and inhibit the abundance of bacterial amoA without impacting archaeal amoA. In contrast, some NIs confine the hydrolysis of synthetic N and, therefore, keep low NH4+-N concentrations that exhibit no or very slight impact on ammonia oxidizers. Variations in soil properties are more influential in the community structure and abundance of ammonia oxidizers than application of synthetic N fertilizers and NIs. Biological nitrification inhibitors (BNIs) are natural bioactive compounds released from roots of certain plant species, such as sorghum, and could be commercialized to suppress the capacity of nitrifying soil microbes. Mixed application of synthetic and organic N fertilizers enhances NUE and plant N-uptake by reducing ammonia N losses. High salt concentration promotes community abundance while limiting the diversity of AOB and vice versa for AOA, whereas AOA have lower rate for potential nitrification than AOB, and denitrification accounts for higher N2 production. Archaeal abundance, diversity, and structural composition change along an elevation gradient and mainly depend on various soil factors, such as soil saturation, availability of NH4+, and organic matter contents. Microbial abundance and structural analyses revealed that the structural composition of AOA was not highly responsive to changes in soil conditions or N amendment. Further studies are suggested to cultivate AOA and AOB in controlled-environment experiments to understand the mechanisms of AOA and AOB under different conditions. Together, this evaluation will better facilitate the projections and interpretations of ammonia oxidizer community structural composition with provision of a strong basis to establish robust testable hypotheses on the competitiveness between AOB and AOA. Moreover, after this evaluation, managing soils agronomically for potential utilization of metabolic functions of ammonia oxidizers would be easier.

Study of changes in groundwater quality indicators during operation of water intake well

Groundwater is one of the main sources of providing people with drinking water. However, during the period of operation of water wells, the quantitative and qualitative characteristics of groundwater change significantly. These changes depend on many factors of natural and man-made origin, in particular, depletion of reserves, conditions of operation and construction of wells, anthropogenic impact on the environment and so on. To assess the water quality of the underground source intended for water supply of one of the facilities in Kyiv, a number of studies of the quality of water extracted from a well 67 m deep were compared. Experiments conducted after the well in 2010 and 2021 were compared. The analysis of the obtained results showed changes in the indicators of groundwater quality during the well operation, which relate to water turbidity, color, total hardness, dry residue, total iron and manganese content.&#x0D; In the current operating conditions of the water intake, the groundwater raised to the surface does not meet the current regulatory quality requirements, and therefore it needs to be purified before it is delivered to consumers. For this case and the need to provide water to a small facility, it is recommended to use the technology of deironing water by biological oxidation. The use of a bioreactor with an insoluble carrier and a contact-clarifying filter with expanded polystyrene loading is proposed. The technology has shown high efficiency in both laboratory and production conditions for local water mains.

Microbial communities contribute to the elimination of As, Fe, Mn, and NH4+ from groundwater in household sand filters

Household sand filters (SFs) are widely applied to remove iron (Fe), manganese (Mn), arsenic (As), and ammonium (NH4+) from groundwater in the Red River delta, Vietnam. Processes in the filters probably include a combination of biotic and abiotic reactions. However, there is limited information on the microbial communities treating varied groundwater compositions and on whether biological oxidation of Fe(II), Mn(II), As(III), and NH4+ contributes to the overall performance of SFs. We therefore analyzed the removal efficiencies, as well as the microbial communities and their potential activities, of SFs fed by groundwater with varying compositions from low (3.3 μg L−1) to high (600 μg L−1) As concentrations. The results revealed that Fe(II)-, Mn(II)-, NH4+-, and NO2−-oxidizing microorganisms were prevalent and contributed to the performance of SFs. Additionally, groundwater composition was responsible for the differences among the present microbial communities. We found i) microaerophilic Fe(II) oxidation by Sideroxydans in all SFs, with the highest abundance in SFs fed by low-As and high-Fe groundwater, ii) Hyphomicropbiaceae as the main Mn(II)-oxidizers in all SFs, iii) As sequestration on formed Fe and Mn (oxyhydr)oxide minerals, iv) nitrification by ammonium-oxidizing archaea (AOA) followed by nitrite-oxidizing bacteria (NOB), and v) unexpectedly, the presence of a substantial amount of methane monooxygenase genes (pmoA), suggesting microbial methane oxidation taking place in SFs. Overall, our study revealed diverse microbial communities in SFs used for purifying arsenic-contaminated groundwater, and our data indicate an important contribution of microbial activities to the key functional processes in SFs.

Microbial diversity response to geochemical gradient characteristics on AMD from abandoned Dashu pyrite mine in Southwest China.

The formation and release of acid mine drainage (AMD) have caused extremely serious pollution in the environment around many mining areas. The biological oxidation of metal sulfide minerals causes the production and release of AMD. To understand the interaction mechanism between microbial and AMD, the study uses Southwest Dashu pyrite as an example to investigate the geochemical gradient characteristics and microbial diversity response on AMD from abandoned mine. Through collecting and testing the water samples, the geochemical parameters such as physical and chemical indexes, main ion composition and microbial community composition of seven mine drainage points were obtained. The results showed that the geochemical and microbial community structure the decrease of AMD pollution in the study area with the decrease of altitude has obvious gradient characteristics. Although AMD has the distribution of acid-resistant iron and sulfur bacteria oxidizing bacteria, the microbial community diversity has obvious gradient characteristics. The categories with a relative abundance of > 5% include Proteobacteria, Actinobacteriota, Firmicutes, WPS-2, Chloroflexi, Bacteroidota, and Acidobacteriota. Actinobacteriota, which was common in the AMD, was distributed throughout the samples. The correlation analysis between water quality parameters and microbial community showed that the microbial community structure was affected by environmental factors. With the increase of acidity and metal ion content, the diversity of microbial community decreased, and the content of acid-resistant iron and sulfur oxidizing bacteria increased. The results showed that pH, dissolved oxygen (Do), the total iron (Fe) content (TFe), SO42-, and Al3+ were the five parameters that most affected microbiological diversity and interaction. Hydrogeochemistry and major ions analysis revealed that AMD in the study area mainly comes from the biological oxidation of metal sulfides and the dissolution and cation exchange of other minerals around the deposit. The degree of AMD pollution is related to the hydrogeochemical conditions in the mine. The higher the mine's water level, the lower the pollutants, and the less AMD is produced and released. The findings confirmed that geochemical gradients significantly changed the biota of the mine water and enriched the related microbial diversity adapted to different environmental factors. Therefore, the findings provide strong support for mine containment to inhibit oxidation and lay the foundation for prevention and control strategies of AMD pollution sources.

Comparative Analysis of the Mitochondrial DNA of Wild Varieties and Domesticated Pleurotus citrinopileatus

In this study, the mitochondrial DNA of wild and domesticated Pleurotus citrinopileatus varieties were sequenced, assembled, and compared. The three mitochondrial DNA of 4681-0, 4681-1, and 4681-2 comprised circular DNA molecules, with the size of 60,331 bp, 60,661 bp and 60,661 bp, respectively. All mitochondrial DNA of the three contained 2 ribosomal RNA genes (rRNAs) and 24 transfer RNA genes (tRNAs). Both 4681-1 and 4681-2 had 17 standard protein-encoding genes, which was higher than 4681-0. Both 4681-0 and 4681-2 had 7 open reading frames, which was less than 4681-1. Among mitochondrial DNA of three varieties, we found gene and intron gain/loss events. By performing a comparative analysis of mitochondrial DNA of three varieties, we identifi ed gene rearrangements between 4681-0, 4681-1 and 4681-2. Predictions of the single nucleotide polymorphisms (SNPs) and RNA editing sites of mitochondrial DNA of three varieties, revealed a feasibility of molecular labeling and gene editing at the mRNA level of P. citrinopileatus. We proposed that mitochondrial DNA, which plays an important role in biological oxidation, is changed to adapt different environments during the domestication of wild species of P. citrinopileatus. We promit an evolutionary strategie of domestication of P. citrinopileatus, aiming to provide some molecular-level theoretical foundations for factory cultivation and genetic breeding of P. citrinopileatus.