Evaluating the low-rank coal degradation efficiency bioaugmented with activated sludge.

Microbial bioaugmentation of coal is considered as a viable and ecologically sustainable approach for the utilization of low-rank coals (LRC). The search for novel techniques to derive high-value products from LRC is currently of great importance. In response to this demand, endeavors have been undertaken to develop microbially based coal solubilization and degradation techniques. The impact of supplementing activated sludge (AS) as a microbial augmentation to enhance LRC biodegradation was investigated in this study. The LRC and their biodegradation products were characterized using the following methods: excitation-emission Matrices detected fluorophores at specific wavelength positions (O, E, and K peaks), revealing the presence of organic complexes with humic properties. FTIR indicated the increased amount of carboxyl groups in the bioaugmented coals, likely due to aerobic oxidation of peripheral non-aromatic structural components of coal. The bacterial communities of LRC samples are primarily composed of Actinobacteria (up to 36.2%) and Proteobacteria (up to 25.8%), whereas the Firmicutes (63.04%) was the most abundant phylum for AS. The community-level physiological profile analysis showed that the microbial community AS had high metabolic activity of compared to those of coal. Overall, the results demonstrated successful stimulation of LRC transformation through supplementation of exogenous microflora in the form of AS.

Time-dependent interference of surfactants and CeO2/Fe2O3 nanoparticles co-occurrence on the volatile fatty acids biosynthesis during semi-continuous sludge fermentation.

Various exogenous contaminants typically coexist in waste activated sludge (WAS), and the long-term impacts of these co-occurring contaminants on WAS anaerobic fermentation and associated mechanisms remain largely unknown. This study reveals that the co-occurrence of surfactants and nanoparticles (NPs, i.e., Fe2O3 and CeO2, frequently detected in sludge) exhibited time-dependent impacts on the volatile fatty acids (VFAs) biosynthesis. Surfactants triggered WAS decomposition and enhanced NPs dispersion, leading to increased exposure of functional anaerobes to NPs toxicity, negatively affecting them. Consequently, key fermentation processes, acidogenic bacterial abundance, and metabolic functions were inhibited in co-occurrence reactors compared to those containing only surfactants in the early stage (before 56 d). Surprisingly, the fermentation systems containing surfactants collapsed subsequently, with VFAs yield at 72 d decreasing by 48.59-71.27 % compared to 56 d. The keystone microbes (i.e., Acidobacteria (16 d) vs Patescibacteria (56 d)) were reshaped, and metabolic traits (i.e., proB involved in intracellular metabolism) were downregulated by 0.05-78.02 % due to reduced microbial adaptive capacity (i.e., quorum sensing (QS)). Partial least squares path modeling (PLS-PM) analysis suggests that the microbial community was the predominant factor influencing VFAs generation. This study provides new insights into the long-term effects of co-contaminants on the biological treatment of WAS.

Nocardioides imazamoxiresistens sp. nov. Isolated from the Activated Sludge.

A Gram-staining-positive actinomycete named YZH12T was isolated from the sediment of the Yangtze River in Nanjing, Jiangsu province, China. Cells were aerobic, non-spore forming, non-motile, short rod (0.4-0.6 × 0.5-1.0 µm) or coccus (0.4-0.6 µm in diameter). Colonies were circular, smooth, and beige to yellowish. Growth occurred at 15-42 °C (optimal 28 °C), pH 5.0-9.0 (optimal 7.0), and 0-10% (w/v) NaCl (optimal 2%). The strain could tolerate 1500 mg/L of imazamox. Strain YZH12T showed 98.7% 16S rRNA gene sequence similarity Nocardioides zeae JM-1068T and less than 97% similarities with other type strains in the genus Nocardioides. Phylogenetic analysis based on genome and 16S rRNA gene sequences indicated that strain YZH12T was phylogenetically affiliated to the genus Nocardioides and formed a subclade with N. zeae JM-1068T and N. alkalitolerans DSM 16699T. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between YZH12T and closely related type strain N. zeae JM-1068T were 79.9% and 35.2%, respectively. The major fatty acids (> 5%) were C18: 1ω9c, iso-C16: 0, C16: 0, C17: 1ω8cand C18: 0; the major respiratory quinone was MK-8(H4); and the polar lipids profiles were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), glycolipid (GL), two aminophospholipids (APL1, APL2), and an unknown polar lipid (L). The genomic DNA G + C content is 73.5%. Based on the phenotypic, chemotaxonomic, phylogenetic analyses, and genomic data, strain YZH12T represents a novel species of the genus Nocardioides, for which the name Nocardioides imazamoxiresistens YZH12T is proposed, with strain YZH12T (= KCTC 49964T = MCCC 1K0892T) as the type strain.

Tessaracoccus lacteus sp. nov., Isolated from the Sludge of a Wastewater Treatment Plant.

A bacterium, designated strain T21T, that is non-motile, rod-shaped, and formed pale white colonies, was isolated from the sludge of a wastewater treatment plant's secondary sedimentation tank in China. Strain T21T could grow at 20-40 °C (optimum growth at 30 °C), pH 3.0-10.0 (optimum growth at pH 5.0) and in the presence of 0-8.0% (w/v) NaCl (optimum growth at 2.0%). Based on phylogenetic analysis of 16S rRNA gene sequences and genome sequences, the isolate belongs to the genus Tessaracoccus in the phylum Actinomycetota. It exhibited a close relationship with Tessaracoccus palaemonis J1M15T, Tessaracoccus defluvii LNB-140T, Tessaracoccus flavescens SST-39T, and Tessaracoccus coleopterorum HDW20T. The 16S rRNA gene sequence similarities are 99.8%, 97.9%, 97.9%, and 97.8%, respectively. The major cellular fatty acids were anteiso-C15:0 and C16:0. The main respiratory quinone was MK-9(H4). The polar lipids included phosphatidylglycerol, diphosphatidylglycerol, glycolipid, and phospholipid. Genome annotation of strain T21T predicted the presence of 2829 genes, of which 2754 are coding proteins and 59 are RNA genes. The genomic DNA G+C content was 69.2%. Based on the results of phylogenetic, phenotypic, chemotaxonomic, and genotypic analyses, we propose the name Tessaracoccus lacteus sp. nov. for this novel species within the genus Tessaracoccus. The type strain is T21T (=CCTCC AB 2023031T = KCTC 49936T).

Study on cultivation of aerobic granular sludge and its application in degrading lignin models in the sequencing batch biofilter granular reactor.

In this study, three sequencing batch biofilter granular reactors (SBBGRs) were employed to treat model lignin wastewater containing different lignin models (2,6-dimethoxyphenol, 4-methoxyphenol, and vanillin). After 40 days of cultivation, uniform-shaped aerobic granular sludge (AGS) was successfully developed through nutrient supplementation with synthetic wastewater. During the acclimation stage, the chemical oxygen demand (COD) reduction efficiencies of the three reactors showed a trend of initial decreasing (5-20%) and then recovering to a high reduction efficiency (exceeding 90%) in a short period of time. During the stable operation stage, all three reactors achieved COD reduction efficiencies exceeding 90%. These findings indicated the cultivated AGS's robust resistance to changes in lignin models in water. UV-Vis spectra analysis confirmed the effective degradation of the three lignin models. Microbiological analysis showed that Proteobacteria and Bacteroidetes were always the dominant phyla. At the genus level, while Acinetobacter (15.46%) dominated in the inoculation sludge, Kapabacteriales (7.93%), SBR1031 (11.77%), and Chlorobium (25.37%) were dominant in the three reactors (for 2,6-dimethoxyphenol, 4-methoxyphenol, and vanillin) after degradation, respectively. These findings demonstrate that AGS cultured with SBBGR effectively degrades lignin models, with different dominant strains observed for various lignin models.

Microbial community changes and metabolic pathways analysis during waste activated sludge and meat processing waste anaerobic co-digestion.

Waste activated sludge (WAS) and meat processing waste (MPW) were acted as co-substrates in anaerobic co-digestion (AcD), and biochemical methane potential (BMP) test was carried out to investigate the methane production performances. Microbial community structure and metabolic pathways analyses were conducted by 16S rRNA high-throughput sequencing and functional prediction analysis. BMP test results indicated that AcD of 70% WAS+30% MPW and 50% WAS+50% MPW (VS/VS) could significantly improve methane yield to 371.05 mL/g VS and 599.61 mL/g VS, respectively, compared with WAS acting as sole substrate (191.87 mL/g VS). The results of microbial community analysis showed that Syntrophomonas and Petrimonas became the dominant bacteria genera, and Methanomassiliicoccus and Methanobacterium became the dominant archaea genera after MPW addition. 16S functional prediction analysis results indicated that genes expression of key enzymes involved in syntrophic acetate oxidation (SAO), hydrogenotrophic and methylotrophic methanogenesis were up-regulated, and acetoclastic methanogenesis was inhibited after MPW addition. Based on these analyses, it could be inferred that SAO combined with hydrogenotrophic and methylotrophic methanogenesis was the dominant pathway for organics degradation and methane production during AcD. These findings provided systematic insights into the microbial community changes and metabolic pathways during AcD of WAS and MPW.

Biological Characterization and Genomic Analysis of Three Novel Serratia- and Enterobacter-Specific Virulent Phages.

Due to the high microbiological contamination of raw food materials and the increase in the incidence of multidrug-resistant bacteria, new methods of ensuring microbiological food safety are being sought. One solution may be to use bacteriophages (so-called phages) as natural bacterial enemies. Therefore, the aim of this study was the biological and genomic characterization of three newly isolated Serratia- and Enterobacter-specific virulent bacteriophages as potential candidates for food biocontrol. Serratia phage KKP_3708 (vB_Sli-IAFB_3708), Serratia phage KKP_3709 (vB_Sma-IAFB_3709), and Enterobacter phage KKP_3711 (vB_Ecl-IAFB_3711) were isolated from municipal sewage against Serratia liquefaciens strain KKP 3654, Serratia marcescens strain KKP 3687, and Enterobacter cloacae strain KKP 3684, respectively. The effect of phage addition at different multiplicity of infection (MOI) rates on the growth kinetics of the bacterial hosts was determined using a Bioscreen C Pro growth analyzer. The phages retained high activity in a wide temperature range (from -20 °C to 60 °C) and active acidity values (pH from 3 to 12). Based on transmission electron microscopy (TEM) imaging and whole-genome sequencing (WGS), the isolated bacteriophages belong to the tailed bacteriophages from the Caudoviricetes class. Genomic analysis revealed that the phages have linear double-stranded DNA of size 40,461 bp (Serratia phage KKP_3708), 67,890 bp (Serratia phage KKP_3709), and 113,711 bp (Enterobacter phage KKP_3711). No virulence, toxins, or antibiotic resistance genes were detected in the phage genomes. The lack of lysogenic markers indicates that all three bacteriophages may be potential candidates for food biocontrol.

Quorum sensing gene lasR promotes phage vB_Pae_PLY infection in Pseudomonas aeruginosa.

BACKGROUND: Quorum sensing (QS) is a cell density-based intercellular communication system that controls virulence gene expression and biofilm formation. In Pseudomonas aeruginosa (P. aeruginosa), the LasR system sits at the top of the QS hierarchy and coordinates the expression of a series of important traits. However, the role of lasR in phage infection remains unclear. This study aims to investigate the role of lasR QS in phage infection. METHODS: The P. aeruginosa phage was isolated from sewage, and its biological characteristics and whole genome were analyzed. The adsorption receptor was identified via a phage adsorption assay. Following lasR gene knockout, the adsorption rate and bactericidal activity of phage were analyzed. Finally, real-time quantitative polymerase chain reaction (RT-qPCR) was conducted to explore how lasR promoting phage infection. RESULTS: The lytic phage vB_Pae_PLY was isolated and lipopolysaccharide (LPS) was identified as its adsorption receptor. The adsorption rate and bactericidal activity of vB_Pae_PLY were reduced after lasR knockout. RT-qPCR results showed that the expression of galU, a key gene involved in LPS synthesis, was down-regulated, and several genes related to type IV pili (T4P) were also down-regulated in the lasR mutant PaΔlasR. CONCLUSIONS: The study showed that QS lasR may promote phage vB_Pae_PLY infection by involving in the synthesis of LPS and T4P. This study provides an example of QS in promoting phage infection and deepens the understanding of phage-bacteria interactions.

Corallococcus caeni sp. nov., a novel myxobacterium isolated from activated sludge.

Two myxobacterial strains (KH5-1T and NO1) were isolated from the activated sludge tanks treating municipal sewage wastewater in Japan. These strains were recognised as myxobacteria based on their phenotypic characteristics of swarming colonies and fruiting bodies. Phylogenetic analyses using the 16S rRNA gene revealed that strains KH5-1T and NO1 were affiliated with the genus Corallococcus, with the closest neighbours being Corallococcus exercitus AB043AT (99.77% and 99.84%, respectively). Genome comparisons using orthologous average nucleotide identity (orthoANI) and digital DNA-DNA hybridisation similarity (dDDH) with strains KH5-1T and NO1 and their phylogenetically close relatives in Corallococcus spp. were below the thresholds. The major cellular fatty acids of strains KH5-1T and NO1 were iso-C15:0 (31.9%, 30.0%), summed feature 3 (comprising C16:1ω7c and/or C16:1ω6c) (20.2%, 17.7%), and iso-C17:0 (12.1%, 14.8%), and the major respiratory quinone was found to be menaquinone (MK)-8. Based on the phenotypic, chemotaxonomic, and phylogenetic evidence, strains KH5-1T and NO1 represent a new species in the genus Corallococcus, for which the proposed name is Corallococcus caeni sp. nov. The type strain is KH5-1T (= NCIMB 15510T = JCM 36609T).

Bioremediation of petroleum refinery wastewater using Bacillus subtilis IH-1 and assessment of its toxicity.

Environmental contamination from petroleum refinery operations has increased due to the rapid population growth and modernization of society, necessitating urgent repair. Microbial remediation of petroleum wastewater by prominent bacterial cultures holds promise in circumventing the issue of petroleum-related pollution. Herein, the bacterial culture was isolated from petroleum-contaminated sludge samples for the valorization of polyaromatic hydrocarbons and biodegradation of petroleum wastewater samples. The bacterial strain was screened and identified as Bacillus subtilis IH-1. After six days of incubation, the bacteria had degraded 25.9% of phenanthrene and 20.3% of naphthalene. The treatment of wastewater samples was assessed using physico-chemical and Fourier-transform infrared spectroscopy analysis, which revealed that the level of pollutants was elevated and above the allowed limits. Following bacterial degradation, the reduction in pollution parameters viz. EC (82.7%), BOD (87.0%), COD (80.0%), total phenols (96.3%), oil and grease (79.7%), TKN (68.8%), TOC (96.3%) and TPH (52.4%) were observed. The reduction in pH and heavy metals were also observed after bacterial treatment. V. mungo was used in the phytotoxicity test, which revealed at 50% wastewater concentration the reduction in biomass (30.3%), root length (87.7%), shoot length (93.9%), and seed germination (30.0%) was observed in comparison to control. When A. cepa root tips immersed in varying concentrations of wastewater samples, the mitotic index significantly decreased, suggesting the induction of cytotoxicity. However, following the bacterial treatment, there was a noticeable decrease in phytotoxicity and cytotoxicity. The bacterial culture produces lignin peroxidase enzyme and has the potential to degrade the toxic pollutants of petroleum wastewater. Therefore the bacterium may be immobilised or directly used at reactor scale or pilot scale study to benefit the industry and environmental safety.

Denitrificimonas halotolerans sp. nov., a novel species isolated from UASB sludge treating landfill leachate.

A Gram-stain-negative, facultative anaerobe, rod-shaped strain JX-1T was isolated from UASB sludge treating landfill leachate in Wuhan, China. The isolate is capable of growing under conditions of pH 6.0-11.0 (optimum, pH 7.0-8.0), temperature 4-42 â„ƒ (optimum, 20-30 â„ƒ), 0-8.0% (w/v) NaCl (optimum, 5.0%), and ammonia nitrogen concentration of 200-5000 mg/L (optimum, 500 mg/L) on LB plates. The microorganism can utilize malic acid, D-galactose, L-rhamnose, inosine, and L-glutamic acid as carbon sources, but does not reduce nitrates and nitrites. The major fatty acids are C18:1ω7c/C18:1ω6c, iso-C15:0, and anteiso-C15:0. The respiratory quinones are Q9 (91.92%) and Q8 (8.08%). Polar lipids include aminolipid, aminophospholipid, diphosphatidylglycerol, glycolipid, phosphatidylethanolamine, phosphatidylglycerol, and phospholipid. Compared with other strains, strain JX-1T and Denitrificimonas caeni HY-14T have the highest values in terms of 16S rRNA gene sequence similarity (96.79%), average nucleotide identity (ANI; 76.06%), and average amino acid identity (AAI; 78.89%). Its digital DNA-DNA hybridization (dDDH) result is 20.3%. The genome of strain JX-1T, with a size of 2.78 Mb and 46.12 mol% G + C content, lacks genes for denitrification and dissimilatory nitrate reduction to ammonium (DNRA), but contains genes for ectoine synthesis as a secondary metabolite. The results of this polyphasic study allow genotypic and phenotypic differentiation of the analysed strain from the closest related species and confirm that the strain represents a novel species within the genus Denitrificimonas, for which the name Denitrificimonas halotolerans sp. nov. is proposed with JX-1T (= MCCC 1K08958T = KCTC 8395T) as the type strain.

Metabolomics-based estimation of activated sludge microbial composition and prediction of filamentous bulking.

Understanding the structure and activity of activated sludge (AS) microbiome is key to ensuring optimal operation of wastewater treatment processes. While high-throughput metagenomics offers a comprehensive view of AS microbiome, its cost and time demands warrant alternative approaches. This study employed machine learning methods to integrate metabolomic and metagenomic data, enabling predictions of selected microbial abundances from metabolite profiling. Model training relied on rich microbial and metabolite abundance data collected in an intensively sampled AS system, including a period of filamentous bulking, as well as a few other AS systems. Multiple linear regression out-competed other three algorithms in achieving relatively high prediction accuracy (R2 = 0.70±0.02) for the abundances of 10 selected, either keystone or core metagenome-assembled genomes (MAGs). The model predicted the abundances of filamentous Microtrichaceae and Thiotrichaceae during bulking with an error range of 14-17.8 %. This predictive power extends beyond the specific system studied, showcasing potentials for broader applications across other AS systems. Aspartate, glycine, and folate were the most influential metabolite features contributing to model performance, which were also effective indicators for filamentous bulking, with up to one week of early warning potential. This study pioneers the application of metabolomics for fast, relatively accurate and cost-effective prediction of AS community composition, enabling proactive management of AS systems towards improved efficiency and stability.

Regulation of intracellular process by two-component systems: Exploring the mechanism of plasmid-mediated conjugative transfer.

Plasmid-mediated conjugative transfer facilitates the dissemination of antibiotic resistance, yet the comprehensive regulatory mechanisms governing this process remain elusive. Herein, we established pure bacteria and activated sludge conjugation system to investigate the regulatory mechanisms of conjugative transfer, leveraging metformin as an exogenous agent. Transcriptomic analysis unveiled that substantial upregulation of genes associated with the two-component system (e.g., AcrB/AcrA, EnvZ/Omp, and CpxA/CpxR) upon exposure to metformin. Furthermore, downstream regulators of the two-component system, including reactive oxygen species (ROS), cytoplasmic membrane permeability, and adenosine triphosphate (ATP) production, were enhanced by 1.7, 1.4 and 1.1 times, respectively, compared to the control group under 0.1 mg/L metformin exposure. Moreover, flow sorting and high-throughput sequencing revealed increased microbial community diversity among transconjugants in activated sludge systems. Notably, the antibacterial potential of human pathogenic bacteria (e.g., Bacteroides, Escherichia-Shigella, and Lactobacillus) was augmented, posing a potential threat to human health. Our findings shed light on the spread of antibiotic resistance bacteria and assess the ecological risks associated with plasmid-mediated conjugative transfer in wastewater treatment systems.

Two risk assessments: Evaluating the use of indicator HF183 Bacteroides versus pathogen measurements for modelling recreational illness risks in an urban watershed.

The purpose of this study was to evaluate the performance of HF183 Bacteroides for estimating pathogen exposures during recreational water activities. We compared the use of Bacteroides-based exposure assessment to exposure assessment that relied on pathogen measurements. We considered two types of recreational water sites: those impacted by combined sewer overflows (CSOs) and those not impacted by CSOs. Samples from CSO-impacted and non-CSO-impacted urban creeks were analysed by quantitative polymerase chain reaction (qPCR) for HF183 Bacteroides and eight human gastrointestinal pathogens. Exposure assessment was conducted two ways for each type of site (CSO-impacted vs. non-CSO impacted): 1) by estimating pathogen concentrations from HF183 Bacteroides concentrations using published ratios of HF183 to pathogens in sewage and 2) by estimating pathogen concentrations from qPCR measurements. QMRA (quantitative microbial risk assessment) was then conducted for swimming, wading, and fishing exposures. Overall, mean risk estimates varied from 0.27 to 53 illnesses per 1,000 recreators depending on exposure assessment, site, activity, and norovirus dose-response model. HF183-based exposure assessment identified CSO-impacted sites as higher risk, and the recommended HF183 risk-based threshold of 525 genomic copies per 100 mL was generally protective of public health at the CSO-impacted sites but was not as protective at the non-CSO-impacted sites. In the context of our urban watershed, HF183-based exposure assessment over- and under-estimated risk relative to exposure assessment based on pathogen measurements, and the etiology of predicted pathogen-specific illnesses differed significantly. Across all sites, the HF183 model overestimated risk for norovirus, adenovirus, and Campylobacter jejuni, and it underestimated risk for E. coli and Cryptosporidium. To our knowledge, this study is the first to directly compare health risk estimates using HF183 and empirical pathogen measurements from the same waterways. Our work highlights the importance of site-specific hazard identification and exposure assessment to decide whether HF183 is applicable for monitoring risk.

Dirammox-dominated microbial community for biological nitrogen removal from wastewater.

Direct ammonia oxidation (Dirammox) might be of great significance to advance the innovation of biological nitrogen removal process in wastewater treatment systems. However, it remains unknown whether Dirammox bacteria can be selectively enriched in activated sludge. In this study, a lab-scale bioreactor was established and operated for 2 months to treat synthetic wastewater with hydroxylamine as a selection pressure. Three Dirammox strains (Alcaligenes aquatilis SDU_AA1, Alcaligenes aquatilis SDU_AA2, and Alcaligenes sp. SDU_A2) were isolated from the activated sludge, and their capability to perform Dirammox process was confirmed. Although these three Dirammox bacteria were undetectable in the seed sludge (0%), their relative abundances rapidly increased after a month of operation, reaching 12.65%, 0.69%, and 0.69% for SDU_A2, SDU_AA1, and SDU_AA2, respectively. Among them, the most dominant Dirammox (SDU_A2) exhibited higher nitrogen removal rate (32.35%) than the other two strains (13.57% of SDU_AA1 and 14.52% of SDU_AA2). Comparative genomic analysis demonstrated that the most dominant Dirammox bacterium (SDU_A2) possesses fewer complete metabolic modules compared to the other two less abundant Alcaligenes strains. Our findings expanded the understanding of the application of Dirammox bacteria as key functional microorganisms in a novel biological nitrogen and carbon removal process if they could be well stabilized. KEY POINTS: • Dirammox-dominated microbial community was enriched in activated sludge bioreactor. • The addition of hydroxylamine played a role in Dirammox enrichment. • Three Dirammox bacterial strains, including one novel species, were isolated.

Bioaugmented biological contact oxidation reactor for treating simulated textile dyeing wastewater.

In this study, modified polyamide fibers were used as biocarriers to enrich dense biofilms in a multi-stage biological contact oxidation reactor (MBCOR) in which partitioned wastewater treatment zone (WTZ) and bioaugmentation zone (BAZ) were established to enhance the removal of methyl orange (MO) and its metabolites while minimizing sludge yields. WTZ exhibited high biomass loading capacity (5.75 ± 0.31 g/g filler), achieving MO removal rate ranging from 68 % to 86 % under different aeration condition within 8 h in which the most dominant genus Chlorobium played an important role. In the BAZ, Pseudoxanthomonas was the dominant genus while carbon starvation stimulated the enrichment of chemoheterotrophy and aerobic_chemoheterotrophy genes thereby enhanced the microbial utilization of cell-released substrates, MO as well as its metabolic intermediates. These results revealed the mechanism bioaugmentation on MBCOR in effectively eliminating both MO and its metabolites.

Enhanced medium-chain fatty acid production from sewage sludge by combined electro-fermentation and anaerobic fermentation.

Electro-fermentation (EF) was combined with anaerobic fermentation (AF) to promote medium-chain fatty acid (MCFA) from sewage sludge. Results showed that EF at acidification process significantly increased short-chain fatty acid (SCFA) production of by 0.5 times (82.4 mmol C/L). AF facilitated the chain elongation (CE) process by enhancing the SCFA conversion. Combined EF at acidification and AF at CE (EF-AF) achieved the highest MCFA production of 27.9 mmol C/L, which was 20 %-866 % higher than the other groups. Electrochemical analyses showed that enhanced SCFA and MCFA production was accompanied with good electrochemical performance at acidification and CE. Microbial analyses showed that EF-AF promoted MCFA production by enriching electrochemically active bacteria (EAB, Bacillus sp.). Enzyme analyses indicated that EF-AF promoted MCFA production by enriching the functional enzymes involved in Acetyl-CoA formation and the fatty acid biosynthesis (FAB) pathway. This study provided new insights into the production of MCFA from enhanced sewage sludge.

Amidoxime-grafted cotton fibers with anti-microbial sludge for efficient uranium recovery.

Uranium as a nuclear fuel, its source and aftertreatment has been a hot topic of debate for developers. In this paper, amidoxime and guanidino-modified cotton fibers (DC-AO-PHMG) were synthesized by the two-step functionalization approach, which exhibited remarkable antimicrobial and high uranium recovery property. Adsorption tests revealed that DC-AO-PHMG had excellent selectivity and anti-interference properties, the maximum adsorption capacity of 609.75 mg/g. More than 85 % adsorption capacity could still be kept after 10 adsorption-desorption cycles, and it conformed to the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model as a spontaneous heat-absorbing chemical monolayer process. FT-IR, EDS and XPS analyses speculated that the amidoxime and amino synergistically increased the uranium uptake. The inhibitory activities of DC-AO-PHMG against three aquatic bacteria, BEY, BEL (from Yellow River water and lake bottom silt, respectively) and B. subtilis were significantly stronger, and the uranium adsorption was not impacted by the high bacteria content. Most importantly, DC-AO-PHMG removed up to 94 % of uranium in simulated seawater and extracted up to 4.65 mg/g of uranium from Salt Lake water, which demonstrated its great potential in the field of uranium resource recovery.

Impact of long-term temperature shifts on activated sludge microbiome dynamics and micropollutant removal.

Micropollutants removal efficiency strongly vary across different aerobic wastewater treatment plants, resulting in their frequent detection in surface and ground waters. Seasonal temperature variation is a major factor influencing plant performance, but it is still unclear how prolonged periods of temperature change impact microbiome and micropollutant biotransformation. This work investigates the effect of long-term temperature variation on the microbial dynamics in an activated sludge system, and the impact on micropollutant biotransformation. Sequencing batch reactors were used as model system and 4-40 °C temperature range was studied. 16S rRNA amplicon sequencing showed that temperature drives microbial structure (gDNA) and activity (RNA), rather than time, and this was stronger below 15 °C and above 25 °C. The microbial community was richest and more diverse at 20 °C, while rarer and more specific taxa became predominant over time, at more extreme temperatures. This suggested that less abundant taxa might be responsible for maintaining the biotransformation capability in the activated sludge at extreme temperatures. Micropollutant biotransformation rates mostly deviated from the classic Arrhenius model below 15 °C and above 25 °C, indicating that prolonged exposure to temperature changes leads to temperature-induced taxonomic shifts, resulting in the emerging of different sets of biotransformation pathways over different temperature ranges.

Enhancing Phosphorus Release from Sewage Sludge in Anaerobic Digestion via Thermal Hydrolysis Pretreatment: Insights from Phosphorus Speciation and Molecular Biological Pathways.

This study explores the mechanisms enhancing phosphorus (P) release from sludge in anaerobic digestion (AD) with thermal hydrolysis pretreatment (THP) using sequential chemical extraction, X-ray absorption near-edge structure spectroscopy (XANES), 31P NMR, and multiomics. THP-treated sludge notably increased liquid-phase P by 53.8% over 3 days compared to sewage sludge (SS), identifying solid-phase Fe-P as the primary P source. The THP+AD also provided a higher abundance of bacteria that contributed to P release through multiple pathways (MPRPB), whereas SS+AD enriched some microbial species with single P release pathway. Moreover, species co-occurrence network analysis underlined the pivotal role of P-releasing bacteria in THP+AD, with 8 out of 16 keystones being P-releasers. Among the 63 screened genes that were related to P transformations and release, the poly beta-hydroxybutyrate (PHB) synthesis genes associated with polyphosphate bacteria-mediated P release were more abundant in THP+AD than in SS+AD. Furthermore, the upregulation of genes involved in methyl phosphonate metabolism in the THP-treated sludge enhanced the methane production potential of the AD process. These findings suggested that MPRPB were indeed the main contributors to P release, and enrichment in the THP+AD process enhanced their capability for P liberation.