Acid-tolerant Pseudomonas citronellolis YN-21 exhibits a high heterotrophic nitrification capacity independent of the amo and hao genes.

Heterotrophic nitrifying bacteria are found to be promising candidates for implementation in wastewater treatment systems due to their tolerance to extreme environments. A novel acid-resistant bacterium, Pseudomonas citronellolis YN-21, was isolated and reported to have exceptional heterotrophic nitrification capabilities in acidic condition. At pH 5, the highest NH4+ removal rate of 7.84 mg/L/h was displayed by YN-21, which was significantly higher than the NH4+ removal rates of other strains in neutral and alkaline environments. Remarkably, a distinct accumulation of NH2OH and NO3- was observed during NH4+ removal by strain YN-21, while traditional amo and hao genes were not detected in the genome, suggesting the possible presence of alternative nitrifying genes. Moreover, excellent nitrogen removal performance was displayed by YN-21 even under high concentrations of metal ion stress. Consequently, a broad application prospect in the treatment of leather wastewater and mine tailwater is offered by YN-21.

Plasma-induced nitrogen vacancy-mediated ammonia synthesis over a VN catalyst.

Plasma catalysis has recently been recognized as a promising route for artificial N2 reduction under mild conditions. Here we report a highly active VN catalyst for plasma-catalytic NH3 synthesis via the typical Mars-van Krevelen (MvK) mechanism. Our results indicate that NH3 synthesis occurs through the continuous regeneration and elimination of nitrogen vacancies on the VN surface. With this strategy, the VN catalyst achieves a superhigh NH3 yield of 143.2 mg h-1 gcat.-1 and a competitive energy efficiency of 1.43 gNH3 kW h-1.

Coarse Mask Guided Interactive Object Segmentation.

Interactive object segmentation aims to produce object masks with user interactions, such as clicks, bounding boxes, and scribbles. Click point is the most popular interactive cue for its efficiency, and related deep learning methods have attracted lots of interest in recent years. Most works encode click points as gaussian maps and concatenate them with images as the model's input. However, the spatial and semantic information of gaussian maps would be noised through multiple convolution layers and won't be fully exploited by top layers for mask prediction. To pass click information to top layers exactly and efficiently, we propose a coarse mask guided model (CMG) which predicts coarse masks with a coarse module to guide the object mask prediction. Specifically, the coarse module encodes user clicks as query features and enriches their semantic information with backbone features through transformer layers, coarse masks are generated based on the enriched query feature and fed into CMG's decoder. Benefiting from the efficiency of transformer, CMG's coarse module and decoder module are lightweight and computationally efficient, making the interaction process more smooth. Experiments on several segmentation benchmarks demonstrate the effectiveness of our method, and we get new state-of-the-art results compared with previous works.

[The toxicity of ZnO and CuO nanoparticles on biological wastewater treatment and its detoxification: a review].

The wide use of ZnO and CuO nanoparticles in research, medicine, industry, and other fields has raised concerns about their biosafety. It is therefore unavoidable to be discharged into the sewage treatment system. Due to the unique physical and chemical properties of ZnO NPs and CuO NPs, it may be toxic to the members of the microbial community and their growth and metabolism, which in turn affects the stable operation of sewage nitrogen removal. This study summarizes the toxicity mechanism of two typical metal oxide nanoparticles (ZnO NPs and CuO NPs) to nitrogen removal microorganisms in sewage treatment systems. Furthermore, the factors affecting the cytotoxicity of metal oxide nanoparticles (MONPs) are summarized. This review aims to provide a theoretical basis and support for the future mitigating and emergent treatment of the adverse effects of nanoparticles on sewage treatment systems.

Identifying the role of fired clay minerals on reducing of nitrogen loss and immobilization of organic nitrogen during chicken manure composting.

This study compared effects of clay minerals before and after firing in immobilization of organic nitrogen and reducing of nitrogen loss during chicken manure composting. The clay minerals and fired clay minerals treatments increased organic nitrogen contents and significantly reduced nitrogen loss, the loss was in order CK (52.61%) > M (47.15%) > I (45.90%) > M- (42.58%) > I- (40.59%). Meanwhile, network analysis indicated that core bacterial community associated with nitrogen transformation were more abundant, and conversion effect of single core bacteria on nitrogen components was enhanced in fired clay minerals treatments. In addition, fired clay minerals strengthened correlation between environmental factors, bacterial community and organic nitrogen, and enhanced interaction of abiotic and biotic pathways, which verified by variance partitioning analysis and structural equation model. Therefore, fired clay minerals play a remarkable driving role in formation and immobilization of organic nitrogen.

Fe2+ Alleviated the Toxicity of ZnO Nanoparticles to Pseudomonas tolaasii Y-11 by Changing Nanoparticles Behavior in Solution.

The negative effect of ZnO nanoparticles (ZnO-NPs) on the biological removal of nitrate (NO3-) has received extensive attention, but the underlying mechanism is controversial. Additionally, there is no research on Fe2+ used to alleviate the cytotoxicity of NPs. In this paper, the effects of different doses of ZnO-NPs on the growth and NO3- removal of Pseudomonas tolaasii Y-11 were studied with or without Fe2+. The results showed that ZnO-NPs had a dose-dependent inhibition on the growth and NO3- removal of Pseudomonas tolaasii Y-11 and achieved cytotoxic effects through both the NPs themselves and the released Zn2+. The addition of Fe2+ changed the behavior of ZnO-NPs in an aqueous solution (inhibiting the release of toxic Zn2+ and promoting the aggregation of ZnO-NPs), thereby alleviating the poisonous effect of ZnO-NPs on the growth and nitrogen removal of P. tolaasii Y-11. This study provides a theoretical method for exploring the mitigation of the acute toxicity of ZnO-NPs to denitrifying microorganisms.

[Co-fermentation of kitchen waste and excess sludge for organic acid production: a review].

Resource utilization is an effective way to cope with the rapid increase of kitchen waste and excess sludge, and volatile fatty acids produced by anaerobic fermentation is an important way of recycling organic waste. However, the single substrate limits the efficient production of volatile fatty acids. In recent years, volatile fatty acids produced by anaerobic co-fermentation using different substrates has been widely studied and applied. In this paper, we analyze the characteristics of fermentation to produce acid using kitchen waste and excess sludge alone or mixture. Influences of environmental factors and microbial community structure on the type and yield of volatile fatty acids in the anaerobic fermentation system are discussed in detail. Moreover, we propose future research directions, to provide a reference for recycling kitchen waste and excess sludge.

Exogenous Fe2+ alleviated the toxicity of CuO nanoparticles on Pseudomonas tolaasii Y-11 under different nitrogen sources.

Extensive use of CuO nanoparticles (CuO-NPs ) inevitably leads to their accumulation in wastewater and toxicity to microorganisms that effectively treat nitrogen pollution. Due to the effects of different mediums, the sources of CuO-NPs-induced toxicity to microorganisms and methods to mitigating the toxicity are still unclear. In this study, CuO-NPs were found to impact the nitrate reduction of Pseudomonas tolaasii Y-11 mainly through the action of NPs themselves while inhibiting the ammonium transformation of strain Y-11 through releasing Cu2+. As the content of CuO-NPs increased from 0 to 20 mg/L, the removal efficiency of NO3 - and NH4 + decreased from 42.29% and 29.83% to 2.05% and 2.33%, respectively. Exogenous Fe2+ significantly promoted the aggregation of CuO-NPs, reduced the possibility of contact with bacteria, and slowed down the damage of CuO-NPs to strain Y-11. When 0.01 mol/L Fe2+ was added to 0, 1, 5, 10 and 20 mg/L CuO-NPs treatment, the removal efficiencies of NO3 - were 69.77%, 88.93%, 80.51%, 36.17% and 2.47%, respectively; the removal efficiencies of NH4 + were 55.95%, 96.71%, 38.11%, 20.71% and 7.43%, respectively. This study provides a method for mitigating the toxicity of CuO-NPs on functional microorganisms.