Characteristics variations of size-fractionated anammox granules and identification of the potential effects on these evolutions.

Anaerobic ammonium oxidation (anammox) granulation which contributed to system stabilization and performance improvement has great potential in the field of wastewater nitrogen removal. The researchers fractionated anammox granules into small-size (0.5-0.9 mm), medium-size (1.8-2.2 mm), and large-size (2.8-3.5 mm) categories to examine their properties and mechanisms. Various analyses, including high-throughput sequencing, determination of inorganic elements and extracellular polymeric substances (EPS), and microbial function prediction, were conducted to characterize these granules and understand their impact. The results revealed distinct characteristics among the different-sized granules. Medium-size granules exhibited the highest sphericity, EPS content, and anammox abundance. In contrast, large-size granules had the highest specific surface area, heme c content, specific anammox activity, biodiversity, and abundance of filamentous bacteria. Furthermore, the precipitates within the granules were identified as CaCO3 and MgCO3, with the highest inorganic element content found in the large-size granules. Microbial community and function annotation also varied with granule size. Based on systematic analysis, the researchers concluded that cell growth, chemical precipitation, EPS secretion, and interspecies interaction all played a role in granulation. Small-size granules were primarily formed through cell growth and biofilm formation. As granule size increased, EPS secretion and chemical precipitation became more influential in the granulation process. In the large-size granules, chemical precipitation and interspecies interaction, including synergistic effects with nitrifying, denitrifying, and filamentous bacteria, as well as metabolic cross-feeding, played significant roles in aggregation. This interplay ultimately contributed to higher anammox activity in the large-size granules. By fully understanding the mechanisms involved in granulation, this study provides valuable insights for the acclimation of anammox granules with optimal sizes under different operational conditions.

Gut microbiota mediated inflammation, neuroendocrine and neurotrophic functions involved in the antidepressant-like effects of diosgenin in chronic restraint stress.

BACKGROUND: Diosgenin is a well-known steroid saponin possessing neuroprotective activities. However, it is unknown whether diosgenin could alleviate depression-like symptoms. METHODS: The antidepressant-like effect of diosgenin was investigated in mice induced by chronic restraint stress. The effects of diosgenin on behaviors, inflammation, neuroendocrine, neurotrophic function, and gut microbiota were evaluated. RESULTS: The results showed that diosgenin alleviated the depressive-like behaviors in mice. In addition, diosgenin was found to reduce serum concentrations of proinflammatory cytokines and the activity of the hypothalamic-pituitary-adrenal (HPA) axis. Besides, diosgenin could activate hippocampal brain-derived neurotrophic factor (BDNF)/TrkB/ERK/CREB signaling pathway and improve the expression of postsynaptic protein PSD95. Meanwhile, the neurogenesis which was inhibited by chronic restraint stress, was totally reversed by diosgenin. Moreover, diosgenin increased the abundance of phylum Firmicutes and the genus Lactobacillus in stressed mice. The results further showed that diosgenin caused a strong correlation between gut microbiota composition and inflammation, the HPA axis activity, or hippocampus neurotrophic function. LIMITATIONS: Only male mice were used for evaluation in the present study, which limits the understanding of effects of diosgenin on the both sexes. In addition, the results only indicate microbiota at the phylum or genus mediate the regulation of neuroinflammation, neuroendocrine, and neurotrophic function, but does not elucidate how microbiota modulate the systems via their primary or secondary metabolites. CONCLUSIONS: The present study shows that diosgenin exerts the antidepressant activity, which is associated with the enhancement of neurotrophic function and the inhibition of inflammatory and neuroendocrine activities via the regulation of gut microbiota.

Dissolving the high-cost with acidity: A happy encounter between fluidized struvite crystallization and wastewater from activated carbon manufacture.

Production of wood-based activated carbon (WAC) generates large volume of highly acidic and phosphate-rich wastewater. Currently, the routine treatment (i.e. lime precipitation) creates significant secondary pollution, leading to extra economic and environmental burdens. Here, by exploiting the strong acidity of WAC wastewater, we successfully demonstrate fluidized struvite crystallization as a low-cost treatment alternative. Based on a 12 m3/d on-site pilot-scale system, four different fluidized struvite crystallization scenarios are evaluated from technical, economic, and environmental perspectives. The results show that using MgO with MgCl2 supplement saves 42.8% of the reagent cost when treating phosphate-rich wastewater (i.e. P = 3125.2 mg/L), and also maintains ideal P removal rate and struvite product purity. Meanwhile, the internal circulation mode exhibits higher P recovery (99.2%) than the external mode (55.3%-89.3%), while also demonstrates superior economic and environmental benefit because of less chemical consumption. In addition, the struvite morphology can be turned between pellets with strong crushing strength (external mode) to powder (internal mode). By Life cycle cost (LCC) analysis, we find that, on a treatment scale of 500 m3/d, struvite-based technology saves up to 31.33 million Chinese Yuan (CYN) during a 20-year lifespan, with relative payback period of 2.60 year. The technical, economic, and environmental assessments confirm that the struvite technology is a promising alternative in solving the bottleneck of WAC wastewater treatment.

Response and Adaptation of Microbial Community in a CANON Reactor Exposed to an Extreme Alkaline Shock.

Responses of a microbial community in the completely autotrophic nitrogen removal over nitrite (CANON) process, which was shocked by a pH of 11.0 for 12 h, were investigated. During the recovery phase, the performance, anaerobic ammonia oxidation (anammox) activity, microbial community, and correlation of bacteria as well as the influencing factors were evaluated synchronously. The performance of the CANON process deteriorated rapidly with a nitrogen removal rate (NRR) of 0.13 kg·m-3·d-1, and Firmicutes, spore-forming bacteria, were the dominant phyla after alkaline shock. However, it could self-restore within 107 days after undergoing four stages, at which Planctomycetes became dominant with a relative abundance of 64.62%. Network analysis showed that anammox bacteria (Candidatus Jettenia, Kuenenia, and Brocadia) were positively related to some functional bacteria such as Nitrosomonas, SM1A02, and Calorithrix. Canonical correspondence analysis presented a strong correlation between the microbial community and influencing factors during the recovery phase. With the increase of nitrogen loading rate, the decrease of free nitrous acid and the synergistic effects, heme c content, specific anammox activity (SAA), NRR, and the abundance of dominant genus increased correspondingly. The increase of heme c content regulates the quorum sensing system, promotes the secretion of extracellular polymeric substances, and further improves SAA, NRR, and the relative abundance of the dominant genus. This study highlights some implications for the recovery of the CANON reactor after being exposed to an alkaline shock.

Mass balance and bacterial characteristics in an in-situ full-scale swine wastewater treatment system occurring anammox process.

A spontaneous development of full-scale anaerobic ammonium oxidation (anammox) process was seldom reported, and its operational parameters could supply references in actual applications. This engineered case indicated that anammox process was suitable for treating relatively high-strength ammonium and organics wastewater due to niche differentiation of biofilm. Results of isotope labelling showed that anammox contributed approximately 40% to N-loss in aerobic unit, but this value increased to 78.3% in anoxic tank. Mass balance showed that N-removal via anammox and denitrification pathways were 38.1 and 23.9 g m-3 d-1, and anammox rate was 1.6 times higher than denitrifiaction. The wild-type anammox granules had a high purity, with anammox accounting for 92.2%. Candidatus Brocadia was the predominant species. Mixing sludge had a higher oxygen tolerance compared with granules, although the latter had a higher anammox activity under anaerobic conditions. Moreover, physicochemical precipitation on the surface of granules may be related to granulation mechanism.

Study on the Factors Affecting the Start-Up of Iron-Manganese Co-Oxide Filters for Ammonium and Manganese Removal from Groundwater.

The high concentration of ammonium (NH4⁺-N) and manganese (Mn2+) in underground water poses a major problem for drinking water treatment plants. Effective catalytic oxidative removal of NH4⁺-N and Mn2+ by iron-manganese co-oxide film (MeOx) filters was first developed by our group in a previous study. In this study, several identical pilot-scale filters were employed to optimize the start-up process for simultaneous removal of NH4⁺-N and Mn2+ from potable water supplies. Experiments were conducted to assess the influence of Mn2+ concentration, Fe2+ concentration, filtration rate and dosing time on the start-up period of the filter. Results demonstrated that the ability of the filter to remove completely 1.5 mg/L NH4⁺-N could be achieved on the sixth day at the soonest and the removal of Mn2+ could reach 1 mg/L by the 18th day. Filter R3 feeding with 1 mg/L Fe2+, 2 mg/L Mn2+ and 3.5 mg/L MnO4- during the start-up period exhibited the optimum NH4⁺-N and Mn2+ removal effect. Short dosing time was not conducive to attaining full NH4⁺-N removal in filters, especially the activity of NO2--N conversion to NO3--N. The compositional analysis and element distribution analysis results demonstrated that there was an abundance of C, O, Mn, Mg, Fe, Ca and Si across the entire area of the surface of the filter media and the elemental distribution was homogeneous, which was different from the biofilter media. Knowledge-guided performance optimization of the active iron-manganese co-oxide could pave the way for its future technological use.