Enhancing anammox process at moderate temperature via employing anammox granular sludge reactor effluent addition

The anaerobic ammonium oxidation (anammox) application on mainstream wastewater treatment is limited by the ambient environment and slow growth rate of anammox bacteria. Bulk liquid in established anammox granular sludge bioreactors naturally contains active factors that could potentially boost anammox process under suboptimal conditions. In this study, effluent of a granular sludge-based anammox up-flow anaerobic sludge blanket treating ammonium-rich wastewater was harvested (the effluent is named as UAE) and continuously added into a bioreactor treating low-strength wastewater at 25 °C to study the effects and mechanisms on enhancing the anammox process. The NH4+-N removal efficiencies increased from 6.5% - 32.5% to 89.7% – 93.8%, and anammox genera accounted from 0.1% to 12.1% of microbial community in the receiving reactor with UAE addition. Coupled partial denitrification and dissimilatory nitrate reduction to ammonium (DNRA) processes with anammox were stimulated by UAE addition. Metagenomic analysis showed that the acyl-homoserine lactone-dependent quorum sensing molecules synthesis pathway was enhanced and an increased concentration of C8-HSL from 2.59 ng/L to 4.62 ng/L was observed in the UAE-receiving reactor. Selective amino acid transportation, amino acids biosynthesis and energy metabolic pathways of microbial community were upregulated with UAE addition. We demonstrate UAE as anammox biocatalyst and facilitate a deeper understanding for synergistic effect of active factors in UAE modified microhabitat for anammox metabolism in the UAE-receiving reactor.</p

Enhancing biological dissolved organic nitrogen removal in landfill leachate wastewater: The role of sodium acetate co-metabolism

Dissolved organic nitrogen (DON) comprises approximately 25% of dissolved nitrogen in landfill leachate wastewater (LLW), posing potential risks such as stimulating algal growth and forming disinfection by-products if not treated properly. While DON characterization and removal by physicochemical methods in wastewater treatment systems have been examined, biological strategies for effective DON removal remain less developed. This study explores the influence of sodium acetate addition during denitrification process on LLW DON removal. With sodium acetate addition (Stage I), we achieved 99% ammonia removal, 94% total inorganic nitrogen (TIN) removal, and 45% DON removal. Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) results suggested the majority of sulfur-containing DON molecules were eliminated in Stage I. Conversely, in the absence of sodium acetate (Stage II), while 99% ammonia removal was maintained, TIN removal dropped to around 10%, and DON concentrations (largely sulfur-containing DON) increased by approximately 22%. Cycle tests revealed similar DON reductions in the aerobic phase across both stages, whereas in the anoxic phase, DON concentrations decreased in Stage I but increased in Stage II. Functional gene prediction indicated higher expression of decarboxylase and deaminase genes in Stage I compared to Stage II. Consequently, this study posits that sodium acetate addition enhances DON removal, potentially via co-metabolism.</p

The Grape VlWRKY3 Gene Promotes Abiotic and Biotic Stress Tolerance in Transgenic Arabidopsis thaliana

WRKY transcription factors are known to play important roles in plant responses to various abiotic and biotic stresses. The grape WRKY gene, WRKY3 was previously reported to respond to salt and drought stress, as well as methyl jasmonate and ethylene treatments in Vitis labrusca × V. vinifera cv. ‘Kyoho.’ In the current study, WRKY3 from the ‘Kyoho’ grape cultivar was constitutively expressed in Arabidopsis thaliana under control of the cauliflower mosaic virus 35S promoter. The 35S::VlWRKY3 transgenic A. thaliana plants showed improved salt and drought stress tolerance during the germination, seedling and the mature plant stages. Various physiological traits related to abiotic stress responses were evaluated to gain further insight into the role of VlWRKY3, and it was found that abiotic stress caused less damage to the transgenic seedlings than to the wild-type (WT) plants. VlWRKY3 over-expression also resulted in altered expression levels of abiotic stress-responsive genes. Moreover, the 35S::VlWRKY3 transgenic A. thaliana lines showed improved resistance to Golovinomyces cichoracearum, but increased susceptibility to Botrytis cinerea, compared with the WT plants. Collectively, these results indicate that VlWRKY3 plays important roles in responses to both abiotic and biotic stress, and modification of its expression may represent a strategy to enhance stress tolerance in crops

Enhancing anammox process with granular activated carbon: A study on Microbial Extracellular Secretions (MESs)

Granular activated carbon (GAC), a porous carbon-based material, provides increased attachment space for functional microorganisms and enhances nitrogen removal by facilitating extracellular electron transfer in the anammox process. This study investigates the effects of GAC on the biosynthesis of microbial extracellular secretions (MESs) and explores the roles of these secretions in anammox activities. Four lab-scale reactors were operated: two downstream UASB reactors (D1 and D2) receiving effluents from the upstream UASB reactors (U1: no-GAC, U2: yes-GAC). Our results indicate that MESs were enhanced with the addition of GAC. The effluent from U2 exhibited a 59.62 % higher amino acid content than that from U1. These secretions contributed to an increase in the nitrogen loading rate (NLR) in the downstream reactors. Specifically, NLR in D1 increased from 130.5 to 142.7 g N/m3/day, and in D2, it escalated from 137.5 to 202.8 g N/m3/day, likely through acting as cross-feeding substrates or vital nutrients. D2 also showed increased anammox bacterial activity, enriched Ca. Brocadia population and hao gene abundance. Furthermore, this study revealed that D2 sludge has significantly higher extracellular polymeric substances (EPS) (48.71 mg/g VSS) and a larger average granule size (1.201 ± 0.119 mm) compared to D1 sludge. Overall, GAC-stimulated MESs may have contributed to the enhanced performance of the anammox process.</p

Deciphering the role of granular activated carbon (GAC) in anammox: Effects on microbial succession and communication

Anaerobic ammonium oxidation (anammox) offered an energy-efficient option for nitrogen removal from wastewater. Granular activated carbon (GAC) addition has been reported that improved biomass immobilization, but the role of GAC in anammox reactors has not been sufficiently revealed. In this study, it was observed that GAC addition in an upflow anaerobic sludge blanket (UASB) reactor led to the significantly shortened anammox enrichment time (shortened by 45 days) than the reactor without GAC addition. The nitrogen removal rate was 0.83 kg N/m3/day versus 0.76 kg N/m3/day in GAC and non-GAC reactors, respectively after 255 days’ operation. Acyl-homoserine lactone (AHL) quorum sensing signal molecule C8-HSL had comparable concentrations in both anammox reactors, whereas the signal molecule C12-HSL was more pervasive in the reactor containing GAC than the reactor without GAC. Microbial analysis revealed distinct anammox development in both reactors, with Candidatus Brocadia predominant in the reactor that did not contain GAC, and Candidatus Kuenenia predominant in the reactor that contained GAC. Denitrification bacteria likely supported anammox metabolism in both reactors. The analyses of microbial functions suggested that AHL-dependent quorum sensing was enhanced with the addition of GAC, and that GAC possibly augmented the extracellular electron transfer (EET)-dependent anammox reaction.</p

Rapid enrichment of anammox bacteria for low-strength wastewater treatment: Role of influent nitrite and nitrate ratios in sequencing batch reactors (SBRs)

Anaerobic ammonium oxidation (Anammox) bacteria (AnAOB) have a long doubling time, which represents one of the key challenges for starting up anammox-based reactors. This study investigated the effect of varied nitrite/nitrate ratios on the anammox reactor startup process using five lab-scale anammox sequencing batch reactors (SBRs) (R1-R5). Nitrate addition significantly accelerated AnAOB enrichment startup, particularly during nitrite accumulation phase. The total start-up time was shortened by 55–71 days, compared to the reactor without nitrate. In R1 (nitrite/nitrate=10:0), anammox contributed the highest nitrogen removal percentage (91%), while R2 (nitrite/nitrate=7:3), with nitrate added, exhibited the highest anammox activity (53.84 mg NH4+-N/g VSS/day) in the steady-state phase. As nitrate proportions increased (R3-R5), anammox activity gradually declined due to limited available COD required for the conversion of NO3- to NO2-. Furthermore, it was found that nitrate-added improved the sludge settleability, with lower SVI30. 16S rRNA gene revealed that Ca. Brocadia was the predominant AnAOB in R1, R2 and R3, where nitrite was the primary NOx--N species (≥50%) in the influent. While in the reactor with low concentration of nitrite (R4: nitrite/nitrate=3:7), Ca. Kuenenia was the dominant AnAOB. This study successfully established a complex and balanced ecosystem with multi-species coexistence, where AnAOB served as the primary functional group on nitrogen removal, supported by denitrification bacteria and dissimilatory nitrate reduction to ammonium (DNRA) bacteria. This study proposes a rapid start-up strategy for the anammox process, which overcomes the bottleneck of long start-up time and helps to promote the application of anammox in wastewater treatment.</p

Exploring interactions between quorum sensing communication and microbial development in anammox membrane bioreactor

The long duration required to enrich bacteria that perform anaerobic ammonium oxidation (anammox) limits their wide application in wastewater treatments. Anammox enrichment requires extensive microbial development, but the mechanisms involved are still being studied. Here, a total nitrogen removal rate of 1.22 kg N/m3/day was obtained over 280 days when anammox was enriched in a membrane bioreactor (MBR). Interactions between quorum sensing (QS) and microbial community development were investigated. Acyl-homoserine lactones (AHLs) were detected in the MBR effluent, with C8-HSL having the highest concentration (2.05 ng/L). The specific anammox activity (SAA) of the biomass increased from 335.8 (± 16.4) mg NH4+-N/g VSS/day to 382.9 (± 19.6) mg NH4+-N/g VSS/day with 0.1 μM C8-HSL addition. Anammox bacteria from the genus Candidatus Brocadia were enriched in the MBR. Metagenomic analysis suggested quorum sensing dependent on AHL and c-di-GMP (bis-[3′-5′]-cyclic dimeric guanosine monophosphate) contributed to microbial development. C-di-GMP-dependent quorum sensing may impact the formation of extracellular polymeric substances (EPS) and cell motility of biomass.</p

Temperature Dependence Of AOS Thin Film Nano Transistors For Medical Applications

Temperature Dependence Of AOS Thin Film Nano Transistors For Medical Application

Image_1_The Grape VlWRKY3 Gene Promotes Abiotic and Biotic Stress Tolerance in Transgenic Arabidopsis thaliana.tif

<p>WRKY transcription factors are known to play important roles in plant responses to various abiotic and biotic stresses. The grape WRKY gene, WRKY3 was previously reported to respond to salt and drought stress, as well as methyl jasmonate and ethylene treatments in Vitis labrusca × V. vinifera cv. ‘Kyoho.’ In the current study, WRKY3 from the ‘Kyoho’ grape cultivar was constitutively expressed in Arabidopsis thaliana under control of the cauliflower mosaic virus 35S promoter. The 35S::VlWRKY3 transgenic A. thaliana plants showed improved salt and drought stress tolerance during the germination, seedling and the mature plant stages. Various physiological traits related to abiotic stress responses were evaluated to gain further insight into the role of VlWRKY3, and it was found that abiotic stress caused less damage to the transgenic seedlings than to the wild-type (WT) plants. VlWRKY3 over-expression also resulted in altered expression levels of abiotic stress-responsive genes. Moreover, the 35S::VlWRKY3 transgenic A. thaliana lines showed improved resistance to Golovinomyces cichoracearum, but increased susceptibility to Botrytis cinerea, compared with the WT plants. Collectively, these results indicate that VlWRKY3 plays important roles in responses to both abiotic and biotic stress, and modification of its expression may represent a strategy to enhance stress tolerance in crops.</p

Table_1_The Grape VlWRKY3 Gene Promotes Abiotic and Biotic Stress Tolerance in Transgenic Arabidopsis thaliana.doc

<p>WRKY transcription factors are known to play important roles in plant responses to various abiotic and biotic stresses. The grape WRKY gene, WRKY3 was previously reported to respond to salt and drought stress, as well as methyl jasmonate and ethylene treatments in Vitis labrusca × V. vinifera cv. ‘Kyoho.’ In the current study, WRKY3 from the ‘Kyoho’ grape cultivar was constitutively expressed in Arabidopsis thaliana under control of the cauliflower mosaic virus 35S promoter. The 35S::VlWRKY3 transgenic A. thaliana plants showed improved salt and drought stress tolerance during the germination, seedling and the mature plant stages. Various physiological traits related to abiotic stress responses were evaluated to gain further insight into the role of VlWRKY3, and it was found that abiotic stress caused less damage to the transgenic seedlings than to the wild-type (WT) plants. VlWRKY3 over-expression also resulted in altered expression levels of abiotic stress-responsive genes. Moreover, the 35S::VlWRKY3 transgenic A. thaliana lines showed improved resistance to Golovinomyces cichoracearum, but increased susceptibility to Botrytis cinerea, compared with the WT plants. Collectively, these results indicate that VlWRKY3 plays important roles in responses to both abiotic and biotic stress, and modification of its expression may represent a strategy to enhance stress tolerance in crops.</p