Effects of a novel sawdust-modified carrier on performance, bioaccumulation and microbial community of sequencing batch reactor.

The impact of a novel sawdust-modified carrier on the performance of aerobic sequencing batch reactor (SBR) was examined. Compared with the conventional polyethylene (PE) carrier, the sawdust-modified carrier had coarse surface and porous side wall, which was beneficial for the rapid formation of biofilm. The biomass of sawdust-modified carrier was 3.4 ± 0.7 times more than those of PE carrier at the end of this study. The biofilm gotten from suspended carrier had higher extracellular polymeric substances (EPS) concentrations than activated sludge (AS). The EPS from biofilm contained higher proportions of polysaccharides compared to those from AS. The SBR with addition of sawdust-modified carrier exhibited higher ammonia nitrogen removal efficiency (84.8%) than the one with addition of conventional PE carrier (73.1%) in a typical cycle at 12 h. The volumetric nitrification rates of modified carrier were higher than those of conventional PE carrier. High throughput sequencing revealed that sawdust-modified carriers exhibited greater microbial richness and diversity compared with traditional PE carriers. Saccharimonadales was the most predominant genus that removed organic matter under aerobic condition, whereas Nitrospira was the dominant nitrifying genus. The present study verifies the advantage of sawdust-modified carrier, which has the potential for the full-scale application in the future.

Energetic utilization of corn stalk and elimination of methyl orange in ECMO-like integrated reactor: Co-occurrence of anaerobic digestion and aerobic treatment.

For the simultaneous energetic utilization of corn stalk and azo-dye contaminated wastewater, an ECMO-like integrated reactor was come up to achieve the biogas production and azo-dye degradation during anaerobic digestion (AD). Methyl orange (MO) was selected as the model compound for azo-dye. The ECMO-like reactor included AD main reactor with a spray device and solid-liquid separation components, integrated with an aeration reactor for biogas slurry. Methane yields of corn stalks (100.82 mL/g VS) were highest in the ECMO-like reactor, compared with reactors without aeration. As a stable metabolite, 4-aminobenzenesulfonic acid (4-ABA) was detected in AD, while it was assumed that the metabolites can be further transformed in the ECMO-like reactor (R3), due to the 4-ABA removal efficiency as 92.87 % after 35 days' digestion. Class Alphaproteobacteria and Clostridia were assumed as functional microbes responding to aeration. Overall, this ECMO-like integrated reactor provided a novel biotechnology strategy for agricultural and azo dye waste treatment.

Comparative study on the effects of anionic, cationic, and nonionic polyacrylamide surface modified magnetic micro-particles (MMP) for anaerobic digestion treatment of vegetable waste water (VWW).

Anaerobic digestion provides a solution for the treatment of vegetable waste water (VWW), but there are currently limited targeted treatment methods available. Building upon previous studies, this research investigated the effects of polyacrylamide-modified magnetic micro-particles (MMP) on anaerobic digestion (AD) of VWW. Three variations of these particles were created by grafting anionic, cationic, and non-ionic polyacrylamide (PAM) onto the MMPs' surfaces, resulting in aPAM-MMP, cPAM-MMP, and nPAM-MMP, respectively. In AD experiments, the addition of aPAM-MMP notably enhanced the degradation of chemical oxygen demand (COD) in VWW. COD decreased to 1290 mg/L in the reactor with aPAM-MMP by day 12 and remained low, while the other reactors had COD concentrations of 4137.5, 5510, and 3010 mg/L on the same day, decreasing thereafter. This modification also improved the production and utilization of hydrogen gas and volatile fatty acids (VFAs), along with the conversion of methane. When tested for bioaffinity using fluorescent GFP-E.coli bacteria, the aPAM-MMP, cPAM-MMP, and nPAM-MMP demonstrated increases in fluorescence intensity by 51.66%, 36.13%, and 37.02%, respectively, compared to unmodified MMP when attached with GFP-E.coli. Further analyses of microbial community revealed that the reactor with aPAM-MMP had the highest microbial richness and enriched bacteria capable of organic matter degradation, such as Bacteroidota, Synergistota, Chloroflexi, Halobacterota phyla, and Parabacteroides, Muribaculaceae, and Azotobacter genera. In conclusion, our experiment verifies that APAM-MMP promotes anaerobic treatment of VWW and provides a novel reference point for enhancing VWW degradation.

Core-Shell Au@Nanoplastics as a Quantitative Tracer to Investigate the Bioaccumulation of Nanoplastics in Freshwater Ecosystems.

Studies on the adverse effects of nanoplastics (NPs, particle diameter <1000 nm) including physical damage, oxidative stress, impaired cell signaling, altered metabolism, developmental defects, and possible genetic damage have intensified in recent years. However, the analytical detection of NPs is still a bottleneck. To overcome this bottleneck and obtain a reliable and quantitative distribution analysis in complex freshwater ecosystems, an easily applicable NP tracer to simulate their fate and behavior is needed. Here, size- and surface charge-tunable core-shell Au@Nanoplastics (Au@NPs) were synthesized to study the environmental fate of NPs in an artificial freshwater system. The Au core enables the quantitative detection of NPs, while the polystyrene shell exhibits NP properties. The Au@NPs showed excellent resistance to environmental factors (e.g., 1% hydrogen peroxide solution, simulating gastric fluid, acids, and alkalis) and high recovery rates (>80%) from seawater, lake water, sewage, waste sludge, soil, and sediment. Both positively and negatively charged NPs significantly inhibited the growth of duckweed (Lemna minor L.) but had little effect on the growth of cyanobacteria (Microcystis aeruginosa). In addition, the accumulation of positively and negatively charged NPs in cyanobacteria occurred in a concentration-dependent manner, with positively charged NPs more easily taken up by cyanobacteria. In contrast, negatively charged NPs were more readily internalized in duckweed. This study developed a model using a core-shell Au@NP tracer to study the environmental fate and behavior of NPs in various complex environmental systems.

Combined disposal of methyl orange and corn straw via stepwise adsorption-biomethanation-composting.

Agriculture wastes have been proved to be the potential adsorbents to remove azo dye from textile wastewater, but the post-treatment of azo dye loaded agriculture waste is generally ignored. A three-step strategy including sequential adsorption-biomethanation-composting was developed to realize the co-processing of azo dye and corn straw (CS). Results showed that CS represented a potential adsorbent to remove methyl orange (MO) from textile wastewater, with the maximum MO adsorption capacity of 10.00 ± 0.46 mg/g, deriving from the Langmuir model. During the biomethanation, CS could serve as electron donor for MO decolorization and substrate for biogas production simultaneously. Though the cumulative methane yield of CS loaded with MO was 11.7 ± 2.28% lower than that of blank CS, almost complete de-colorization of MO could be achieved within 72 h. Composting could achieve the further degradation of aromatic amines (intermediates during the degradation of MO) and decomposition of digestate. After 5 days' composting, 4-aminobenzenesulfonic acid (4-ABA) was not detectable. The germination index (GI) also indicated that the toxicity of aromatic amine was eliminated. The overall utilization strategy gives novel light on the management of agriculture waste and textile wastewater.

Use of magnetic powder to effectively improve the denitrification employing the activated sludge fermentation liquid as carbon source.

Nitrogen removal is often limited in municipal wastewater treatment due to the lack of sufficient carbon source. Utilizing volatile fatty acids (VFAs) from waste activated sludge (WAS) fermentation broth as a carbon source is an ideal alternative to reduce the cost for wastewater treatment plants (WWTPs) and improve denitrification efficiency simultaneously. In this study, an anaerobic system was applied for simultaneous denitrification and WAS fermentation and the addition of magnetic microparticles (MMP) were confirmed to enhance both denitrification and WAS fermentation. Firstly, the addition of MMP increased the nitrate reduction rate by over 25.36% and improve the production of N2. Additionally, the equivalent chemical oxygen demand (COD) of the detected VFAs increased by 7.06%-14.53%, suggesting that MMP promoted the WAS fermentation. The electron transfer efficiency of denitrifies was accelerated by MMP via electron-transporting system (ETS) activity and cyclic voltammetry (CV) experiments, which might result in the promotional denitrification and WAS fermentation performance. Furthermore, the high-throughput sequencing displayed that, MMP enriched key microbes capable of degrading the complex organics (Chloroflexi, Synergistota and Spirochaetota) as well as the typical denitrifies (Bacteroidetes_vadinHA17 and Denitratisoma). Therefore, this study provides a novel strategy to realize simultaneous WAS utilization and denitrification for WWTPs.

Improved fertilization efficiency of manure compost obtained by using oil shale semicoke as the bulking agent.

Oil shale semicoke is a kind of solid waste produced during the retorting process of oil shale, which could cause environmental pollution without reasonable disposing. In our previous study, the abandoned semicoke was recycled as bulking agent to reduce the nitrogen loss and greenhouse gases emission during composting. But influences of the obtained semicoke-blended compost on soil properties and plant growth remained unclear, which would be discussed in this study. Through leaching experiments, it was found that the N/P/K retention capacity of soil mixed with semicoke-blended compost significantly increased for the good nutrients sorption capacity of oil shale semicoke. Subsequently, germination test showed the germination index of semicoke-blended compost could attain 120%, implying its low phytotoxicity. And pot experiments exhibited the biomass of cress and Brassica rapa significantly increased by 2-4 times when applying semicoke-blended compost as fertilizer, exhibiting its great benefits to plants. For the increase of crop yield, it was closely related to their elevated nutrients uptake efficiency, also might be related to the improved soil microbial community and activity as the microbial analysis indicated. Finally, results of pollutant detection showed the concentration of polycyclic aromatic hydrocarbons, Cr, As, Cd and Pb in the mature semicoke-blended compost obtained through composting was 2.82, 95.30, 5.95, 0.34 and 14.45 mg kg-1 respectively, meeting the standard for soil application. The research suggests composting could be an effective method for the harmless disposing and resource recycling of oil shale semicoke waste.

Gases emission during the continuous thermophilic composting of dairy manure amended with activated oil shale semicoke.

NH3 and greenhouse gases emission are big problems during composting, which can cause great nitrogen nutrient loss and environmental pollution. This study investigated effects of the porous bulking agent of oil shale semicoke and its activated material on the gases emission during the continuous thermophilic composting. Results showed addition of semicoke could significantly reduce the NH3 emission by 74.65% due to its great adsorption capacity to NH4+-N and NH3, further the effect could be enhanced to 85.92% when utilizing the activated semicoke with larger pore volume and specific surface area. In addition, the CH4 emission in the semicoke and activated semicoke group was also greatly mitigated, with a reduction of 67.23% and 87.62% respectively, while the N2O emission was significantly increased by 93.14% and 100.82%. Quantification analysis of the functional genes found the abundance of mcrA was high at the massive CH4-producing stage and the archaeal amoA was dominant at the N2O-producing stage in all the composting groups. Correlation and redundancy analysis suggested there was a positive correlation between the CH4 emission and mcrA. Addition of semicoke especially activated semicoke could reduce the CH4 production by inhibiting the methanogens. For the NH3 and N2O, it was closely related with the nitrification process conducted by archaeal amoA. Addition of semicoke especially activated semicoke was beneficial for the growth of ammonia-oxidizing archaea, causing the less NH4+-N transformation to NH3 but more N2O emission.

Enrichment of thermophilic and mesophilic microbial consortia for efficient degradation of corn stalk.

Six different environmental samples were applied to enrich microbial consortia for efficient degradation of corn stalk, under the thermophilic and mesophilic conditions. The consortium obtained from anaerobic digested sludge under thermophilic condition (TC-Y) had the highest lignocellulose-degrading activity. The CO2 yield was 246.73 mL/g VS in 23 days, meanwhile, the maximum CO2 production rate was 15.48 mL/(CO2·d), which was 28.75% and 52.27% higher than that under mesophilic condition, respectively. The peak value of cellulase activity reached 0.105 U/mL, which was at least 34.61% higher than the other groups. In addition, 49.5% of corn stalk was degraded in 20 days, moreover, the degradation ratio of cellulose, hemicellulose and lignin can reach 52.76%, 62.45% and 42.23%, respectively. Microbial consortium structure analysis indicated that the TC-Y contained the phylum of Gemmatimonadetes, Acidobacteria, Chloroflexi, Planctomycetes, Firmicutes, and Proteobacteria. Furthermore, the Pseudoxanthomonas belonging to GammaProteobacteria might be the key bacterial group for the lignocellulose degradation. These results indicated the capability of degrading un-pretreated corn stalk and the potential for further investigation and application of TC-Y.

Paludibacter jiangxiensis sp. nov., a strictly anaerobic, propionate-producing bacterium isolated from rice paddy field.

A mesophilic, obligately anaerobic, propionate-producing fermentative bacterium, designated strain NM7(T), was isolated from rural rice paddy field. Cells of strain NM7(T) are Gram-negative, non-motile, non-spore-forming, short rods, and negative for catalase. The strain grew optimally at 37 °C (the range for growth 15-40 °C) and pH 7.0 (pH 5.0-7.5). The strain could grow fermentatively on various sugars, including arabinose, xylose, fructose, galactose, glucose, mannose, cellobiose, lactose, maltose, sucrose, pectin and starch. The main end products of glucose fermentation were acetate and propionate. Yeast extract was not required but stimulated the growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, and Fe(III) nitrilotriacetate were not used as terminal electron acceptors. The G+C content of genomic DNA was 42.8 mol%. The major cellular fatty acids were C15:0, anteiso-C15:0, C16:0, and C17:0. The most abundant polar lipid of strain NM7(T) was phosphatidylethanolamine. 16S rRNA gene sequence analysis revealed that it belongs to the family Porphyromonadaceae of the phylum Bacteroidetes. The closest recognized species was Paludibacter propionicigenes (91.4 % similarity in 16S rRNA gene sequence). A novel species, Paludibacter jiangxiensis sp. nov., is proposed to accommodate strain NM7(T) (=JCM 17480(T) = CGMCC 1.5150(T) = KCTC 5844(T)).

Lactivibrio alcoholicus gen. nov., sp. nov., an anaerobic, mesophilic, lactate-, alcohol-, carbohydrate- and amino-acid-degrading bacterium in the phylum Synergistetes.

A mesophilic, obligately anaerobic, lactate-, alcohol-, carbohydrate- and amino-acid- degrading bacterium, designated strain 7WAY-8-7(T), was isolated from an upflow anaerobic sludge blanket reactor treating high-strength organic wastewater from isomerized sugar production processes. Cells of strain 7WAY-8-7(T) were motile, curved rods (0.7-1.0×5.0-8.0 µm). Spore formation was not observed. The strain grew optimally at 37 °C (range for growth was 25-40 °C) and pH 7.0 (pH 6.0-7.5), and could grow fermentatively on yeast extract, glucose, ribose, xylose, malate, tryptone, pyruvate, fumarate, Casamino acids, serine and cysteine. The main end-products of glucose fermentation were acetate and hydrogen. In co-culture with the hydrogenotrophic methanogen Methanospirillum hungatei DSM 864(T), strain 7WAY-8-7(T) could utilize lactate, glycerol, ethanol, 1-propanol, 1-butanol, L-glutamate, alanine, leucine, isoleucine, valine, histidine, asparagine, glutamine, arginine, lysine, threonine, 2-oxoglutarate, aspartate and methionine. A Stickland reaction was not observed with some pairs of amino acids. Yeast extract was required for growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite and Fe (III) were not used as terminal electron acceptors. The G+C content of the genomic DNA was 61.4 mol%. 16S rRNA gene sequence analysis revealed that the isolate belongs to the uncultured environmental clone clade (called 'PD-UASB-13' in the Greengenes database) in the bacterial phylum Synergistetes, showing less than 90% sequence similarity with closely related described species such as Aminivibrio pyruvatiphilus and Aminobacterium colombiense (89.7% and 88.7%, respectively). The major cellular fatty acids were iso-C(13 : 0), iso-C(15 : 0), anteiso-C(15 : 0), C(18 : 1), C(19 : 1), C(20 : 1) and C(21 : 1). A novel genus and species, Lactivibrio alcoholicus gen. nov., sp. nov. is proposed to accommodate strain 7WAY-8-7(T) ( = JCM 17151(T) = DSM 24196(T) = CGMCC 1.5159(T)).

Terrimicrobium sacchariphilum gen. nov., sp. nov., an anaerobic bacterium of the class 'Spartobacteria' in the phylum Verrucomicrobia, isolated from a rice paddy field.

A strictly anaerobic, mesophilic, carbohydrate-fermenting bacterium, designated NM-5T, was isolated from a rice paddy field. Cells of strain NM-5(T) were Gram-stain-negative, non-motile, non-spore-forming, short rods (0.5-0.7 µm×0.6-1.2 µm). The strain grew optimally at 37 °C (growth range 20-40 °C) and pH 7.0 (pH 5.5-8.0). The strain could grow fermentatively on arabinose, xylose, fructose, galactose, glucose, ribose, mannose, cellobiose, lactose, maltose and sucrose. The main end-products of glucose fermentation were acetate and propionate. Organic acids, alcohols and amino acids were not utilized for growth. Yeast extract was not required but stimulated the growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, and Fe (III) nitrilotriacetate were not used as terminal electron acceptors. The DNA G+C content was 46.3 mol%. The major cellular fatty acids were iso-C14:0, C18:0 and C16:0. 16S rRNA gene sequence analysis revealed that strain NM-5T belongs to the class 'Spartobacteria', subdivision 2 of the bacterial phylum Verrucomicrobia. Phylogenetically, the closest species was 'Chthoniobacter flavus' (89.6% similarity in 16S rRNA gene sequence). A novel genus and species, Terrimicrobium sacchariphilum gen. nov., sp. nov., is proposed. The type strain of the type species is NM-5T (=JCM 17479T=CGMCC 1.5168T).

Hydrogenispora ethanolica gen. nov., sp. nov., an anaerobic carbohydrate-fermenting bacterium from anaerobic sludge.

An anaerobic, spore-forming, ethanol-hydrogen-coproducing bacterium, designated LX-BT, was isolated from an anaerobic sludge treating herbicide wastewater. Cells of strain LX-BT were non-motile rods (0.3-0.5×3.0-18.0 µm). Spores were terminal with a bulged sporangium. Growth occurred at 20-50 °C (optimum 37-45 °C), pH 5.0-8.0 (optimum pH 6.0-7.7) and 0-2.5% (w/v) NaCl. The strain could grow fermentatively on glucose, maltose, arabinose, fructose, xylose, ribose, galactose, mannose, raffinose, sucrose, pectin, starch, glycerol, fumarate, tryptone and yeast extract. The major end-products of glucose fermentation were acetate, ethanol and hydrogen. Yeast extract was not required but stimulated growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite, anthraquinone-2,6-disulfonate, fumarate and Fe (III) nitrilotriacetate were not used as terminal electron acceptors. The G+C content of the genomic DNA was 56.1 mol%. The major cellular fatty acids were anteiso-C15:0, iso-C14:0 and C16:0. The most abundant polar lipids of strain LX-BT were diphosphatidylglycerol and phosphatidylglycerol. 16S rRNA gene sequence analysis revealed that it belongs to an as-yet-unidentified taxon at the order- or class-level (OPB54) within the phylum Firmicutes, showing 86.5% sequence similarity to previously described species of the Desulfotomaculum cluster. The name Hydrogenispora ethanolica gen. nov., sp. nov. is proposed to accommodate strain LX-BT (=DSM 25471T=JCM 18117T=CGMCC 1.5175T) as the type strain.

Acetobacteroides hydrogenigenes gen. nov., sp. nov., an anaerobic hydrogen-producing bacterium in the family Rikenellaceae isolated from a reed swamp.

A strictly anaerobic, mesophilic, carbohydrate-fermenting, hydrogen-producing bacterium, designated strain RL-C(T), was isolated from a reed swamp in China. Cells were Gram-stain-negative, catalase-negative, non-spore-forming, non-motile rods measuring 0.7-1.0 µm in width and 3.0-8.0 µm in length. The optimum temperature for growth of strain RL-C(T) was 37 °C (range 25-40 °C) and pH 7.0-7.5 (range pH 5.7-8.0). The strain could grow fermentatively on yeast extract, tryptone, arabinose, glucose, galactose, mannose, maltose, lactose, glycogen, pectin and starch. The main end products of glucose fermentation were acetate, H2 and CO2. Organic acids, alcohols and amino acids were not utilized for growth. Yeast extract was not required for growth; however, it stimulated growth slightly. Nitrate, sulfate, sulfite, thiosulfate, elemental sulfur and Fe(III) nitrilotriacetate were not reduced as terminal electron acceptors. Aesculin was hydrolysed but not gelatin. Indole and H2S were produced from yeast extract. The G+C content of the genomic DNA was 51.2 mol%. The major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and C16 : 0. The most abundant polar lipid of strain RL-C(T) was phosphatidylethanolamine. 16S rRNA gene sequence analysis revealed that the isolate belongs to the uncultured Blvii28 wastewater-sludge group (http://www.arb-silva.de/) in the family Rikenellaceae of the phylum Bacteroidetes, and shared low sequence similarities with the related species Alistipes shahii WAL 8301(T) (81.8 %), Rikenella microfusus ATCC 29728(T) (81.7 %) and Anaerocella delicata WN081(T) (80.9 %). On the basis of these data, a novel species in a new genus of the family Rikenellaceae is proposed, Acetobacteroides hydrogenigenes gen. nov., sp. nov. The type strain of the type species is RL-C(T) ( = JCM 17603(T) = DSM 24657(T) = CGMCC 1.5173(T)).

Metabolomics reveals stage-specific metabolic pathways of microbial communities in two-stage anaerobic fermentation of corn-stalk.

Analysis of intracellular metabolites is essential to delineate metabolic pathways of microbial communities for evaluation and optimization of anaerobic fermentation processes. The metabolomics are reported for a microbial community during two stages of anaerobic fermentation of corn stalk in a biogas digester using GC­MS. Acetonitrile/methanol/water (2:2:1, by vol) was the best extraction solvent for microbial community analysis because it yielded the largest number of peaks (>200), the highest mean summed value of identified metabolites (23) and the best reproducibility with a coefficient of variation of 30 % among four different extraction methods. Inter-stage comparison of metabolite profiles showed increased levels of sugars and sugar alcohols during methanogenesis and fatty acids during acidogenesis. Identification of stage-specific metabolic pathways using metabolomics can therefore assist in monitoring and optimization of the microbial community for increased biogas production during anaerobic fermentation.

Enhancement of Livestock Wastewater Treatment by a Novel Wooden-modified Biocarrier.

Intensive livestock wastewater poses threat to ecosystem. A novel wooden-modified biocarrier was applied in this study to enhance the livestock wastewater treatment in anoxic-aerobic systems. Compared to the ordinary polyethylene (PE) biocarrier, the novel wooden-modified biocarrier improved the biomass owing to its rough surface and porous side wall, and had better nitrogen removal ability. The biomass of wooden-modified biocarrier was 6.3 ± 1.1 and 36.4 ± 17.0 times that of PE biocarrier in anoxic and aerobic condition, respectively. The removal rates of ammonia nitrogen and total nitrogen of this novel biocarrier on specific biofilm's aera eventually stabilized at 0.64 ± 0.10 and 0.94 ± 0.21 g N/m2/d, respectively. Notably, this wooden-modified biocarrier was conducive to increase nitrogen removal by simultaneous nitrification and denitrification to some extent. The biofilm on novel modified biocarrier had higher extracellular polymeric substances (EPS) contents than activated sludge (AS), and the proportions of polysaccharides (PS) in EPS from biocarrier were more than those from AS. Compared to PE biocarrier and AS, the wooden-modified biocarriers enhanced the enrichment of nitrifying and denitrifying bacteria, and promoted the membrane transport and aerobic nitrogen metabolism. This study confirmed the superiority of wooden-modified biocarrier and provided reference for the treatment of high concentration sewage in full-scale project.

Novel flocking materials as biocarriers in moving bed biofilm reactor for improving simultaneous nitrification and denitrification performance.

Biocarrier is the key factor for the stable operation of moving bed biofilm reactor (MBBR). To achieve efficient simultaneous nitrification and denitrification (SND), this study provided novel flocking materials as biocarriers. The biofilm formation experiment showed that longer flocking carrier was more conducive to biomass accumulation, resulting in greater oxygen uptake rate. The continuous operation results showed that the total nitrogen removal and SND performance of the MBBR with the addition of 5.0 mm flocking carriers reached 52.0 % and 70.5 %, respectively, which were 29.1 % and 33.3 % greater than those of the control. Compared with those in suspended sludge, the extracellular polymeric substances and protein components in the biocarrier were more abundant. Furthermore, the relative abundance of genera related to denitrification and the nitrogen metabolic sequence improved with the addition of the novel flocking biocarriers. This study demonstrated the effectiveness of novel flocking fillers in improving the performance of MBBR.

Life cycle assessment of hydrogenotrophic denitrification in membrane aerated biofilm reactors for sustainable wastewater treatment.

The conventional anaerobic-anoxic-oxic (AAO) process for wastewater treatment is associated with high energy consumption and pollutant emissions due to its reliance on heterotrophic denitrification. In contrast, membrane aerated biofilm reactors (MABR) coupled with hydrogenotrophic denitrification (H2-MABR) offers a more promising alternative. This study conducts a life cycle assessment (LCA) to evaluate the environmental and economic benefits of H2-MABR compared to traditional AAO processes. Results indicate that even with a limited reactor life, the application of MABR in actual wastewater treatment plants can yield over 30 % reduction in environmental and economic impacts. Using CO2 from biogas as a carbon source significantly reduces carbon emissions during the anaerobic stage, while the efficient nitrogen removal minimizes the need for wastewater recirculation and electricity consumption. The H2-driven denitrification process also avoids emissions and secondary pollution risks associated with organic electron donors. Furthermore, coupling H2-MABR with renewable energy source and Power-to-Gas technology further enhances sustainability by ensuring a stable hydrogen supply. Given the significant potential of H2-MABR for improving wastewater treatment, further research and large-scale implementation are highly encouraged.

Simultaneous denitrification enhancement and sludge reduction based on novel suspended carrier modified using activated carbon and magnetite at low carbon/nitrogen ratio.

A novel suspended carrier was prepared by sticking activated carbon (AC) and magnetite (Fe3O4) onto polypropylene slices. Although this carrier could not reverse the decreased denitrification capacity trends under anoxic conditions at an influent carbon/nitrogen (C/N) ratio of 2, it enhanced denitrification by stimulating sludge reduction and accelerating electron transfer to certain extent. The carrier stuck by mixed AC/Fe3O4 exhibited better performance in terms of sludge reduction, extracellular polymeric substances (EPS) secretion, and denitrification than that merely stuck by AC and Fe3O4 at an influent C/N ratio of 2. The carrier stuck by mixed AC/Fe3O4 increased the total nitrogen removal efficiency by 24.6 % ± 12.5 % in a 72-h denitrification batch experiment compared to the common polypropylene carrier. Moreover, the carrier improved EPS secretion and nitrogen metabolism and promoted the growth of Trichococcus and some denitrifying genera. This study provides a reference for the treatment of low C/N ratio sewage.

Oligosphaera ethanolica gen. nov., sp. nov., an anaerobic, carbohydrate-fermenting bacterium isolated from methanogenic sludge, and description of Oligosphaeria classis nov. in the phylum Lentisphaerae.

A mesophilic, obligately anaerobic, carbohydrate-fermenting bacterium, designated 8KG-4(T), was isolated from an upflow anaerobic sludge blanket reactor treating high-strength organic wastewater from salted vegetable production processes. Cells of strain 8KG-4(T) were non-motile, spherical and 0.7-1.5 µm in diameter (mean, 1.0 µm). Spore formation was not observed under any culture conditions tested. The strain grew optimally at 37 °C (range for growth 25-40 °C) and pH 7.0 (range, pH 6.5-7.5), and could grow fermentatively on glucose, ribose, xylose, galactose and sucrose. The main end products of glucose fermentation were acetate, ethanol and hydrogen. Organic acids, alcohols and amino acids were not utilized for growth. Yeast extract was not required for growth. Nitrate, sulfate, thiosulfate, elemental sulfur, sulfite and Fe(III) nitrilotriacetate were not used as terminal electron acceptors. The G+C content of the genomic DNA was 61.1 mol%. 16S rRNA gene sequence analysis revealed that the isolate represented a previously uncultured lineage at the subphylum level within the phylum Lentisphaerae known as 'WWE2 subgroup I'. The major cellular fatty acids were anteiso-C(15 : 0), iso-C(16 : 0), C(16 : 0) and anteiso-C(17 : 0). Respiratory quinones were not detected. The most abundant polar lipid of strain 8KG-4(T) was phosphatidylethanolamine. A novel genus and species, Oligosphaera ethanolica gen. nov., sp. nov., is proposed to accommodate strain 8KG-4(T) ( = JCM 17152(T) = DSM 24202(T)  = CGMCC 1.5160(T)). In addition, we formally propose Oligosphaeria classis nov. and the subordinate taxa Oligosphaerales order nov. and Oligosphaeraceae fam. nov.