Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 37.843
Filtrar
1.
Artigo em Inglês | MEDLINE | ID: mdl-36673724

RESUMO

Macroalgae can be a viable alternative to replace fossil fuels that have a negative impact on the environment. By mixing macroalgae with other substrates, higher quality biogas can be obtained. Such biogas is considered one of the most promising solutions for reducing climate change. In the work, new studies were conducted, during which biogas yield was investigated in a three-stage bioreactor (TSB) during the anaerobic digestion of Cladophora glomerata macroalgae with inoculants from cattle manure and sewage sludge at different organic loading rates (OLR). By choosing the optimal OLR in this way, the goal was to increase the energy potential of biomass. The research was performed at OLRs of 2.87, 4.06, and 8.13 Kg VS/m3 d. After conducting research, the highest biogas yield was determined when OLR was 2.87 Kg VS/m3 d. With this OLR, the average biogas yield was 439.0 ± 4.0 L/Kg VSadded, and the methane yield was 306.5 ± 9.2 L CH4/Kg VSadded. After increasing the OLR to 4.06 and 8.13 Kg VS/m3 d, the yield of biogas and methane decreased by 1.55 times. The higher yield was due to better decomposition of elements C, N, H, and S during the fermentation process when OLR was 2.87 Kg VS/m3 d. At different OLRs, the methane concentration remained high and varied from 68% to 80%. The highest biomass energy potential with a value of 3.05 kWh/Kg VSadded was determined when the OLR was 2.87 Kg VS/m3 d. This biomass energy potential was determined by the high yield of biogas and methane in TSB.


Assuntos
Biocombustíveis , Alga Marinha , Animais , Bovinos , Anaerobiose , Reatores Biológicos , Esgotos , Metano
2.
J Hazard Mater ; 446: 130703, 2023 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-36587594

RESUMO

The excessive input of nutrients into groundwater can accelerate eutrophication in associated surface water systems. This study combined hydrogeochemistry, multi isotope tracers, and microbiological data to estimate nutrient sources and the effects of groundwater-surface water interactions on the spatiotemporal variation of nutrients in groundwater connected to a large weir-regulated river in South Korea. δ11B and δ15N-NO3- values, in combination with a Bayesian mixing model, revealed that manure and sewage contributed 40 % and 25 % respectively to groundwater nitrate, and 42 % and 27 % to nitrate in surface water during the wet season. In the dry season, the source apportionment was similar for groundwater while the sewage contribution increased to 52 % of nitrate in river water. River water displayed a high correlation between NO3- concentration and cyanobacteria (Microcystis and Prochlorococcus) in the wet season. The mixing model using multiple isotopes indicated that manure-derived nutrients delivered with increased contributions of groundwater to the river during the wet season governed the occurrence of cyanobacterial blooms in the river. We postulate that the integrated approach using multi-isotopic and microbiological data is highly effective for evaluating nutrient sources and for delineating hydrological interactions between groundwater and surface water, as well as for investigating surface water quality including eutrophication in riverine and other surface water systems.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Isótopos de Nitrogênio/análise , Rios , Nitratos/análise , Esgotos , Esterco , Teorema de Bayes , Monitoramento Ambiental , Poluentes Químicos da Água/análise , China
3.
Environ Pollut ; 319: 120971, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36603759

RESUMO

Waxy oily sludge (WOS) from petrochemical enterprises has complex components and difficult treatment. Long-term large-scale stacking has seriously threatened human health and the ecological environment. In this paper, a new rapid and effective treatment method combining dispersion and biodegradation in a semi-fluid state was developed for the WOS. The degradation mechanism of the WOS in the bioreactor was preliminarily discussed. The component analysis results showed that the compounds with large molecular weight (M ≥ 282) in the WOS accounted for more than 50%. Among all microbial consortiums, the treatment effect of the consortium FF: NY3 = 9: 1 was the best for treating the crude oil in WOS, which was significantly different from that of a single strain (p < 0.05). Under the optimal nitrogen source NH4NO3 and the concentration of rhamnolipid, the developed high-efficiency microbial consortium (FF: NY3 = 9:1) could remove 85% of the total hydrocarbon pollutants in the 20 L semi-fluid bioreactor within 9 days. The degradation characteristics of WOS components in the bioreactor showed that the developed consortium has good degradation ability for n-alkanes (about 90%), middle- (77.35%)/long-chain (72.66%) isomeric alkanes, alkenes (79.12%), alicyclic hydrocarbons (78.9%) and aromatic hydrocarbons (62.78%). The kinetic analysis results indicated that, in comparison, the middle-chain n-alkanes, middle-chain isomeric saturated alkanes, alkenes, and alicyclic hydrocarbons were most easily removed. The removal rates of long-chain n-alkanes, long-chain isomeric saturated alkanes, and aromatic hydrocarbons were relatively low. The biological toxicity test showed that the germination rate of wheat seeds in treated waxy sludge was Significantly higher than that in untreated waxy sludge (p < 0.01). These results suggest that the new method developed in this paper can treat refractory WOS quickly and effectively. This method lays the foundation for the pilot-scale treatment of the semi-fluid bioreactor.


Assuntos
Petróleo , Esgotos , Humanos , Cinética , Óleos , Hidrocarbonetos/análise , Alcanos/metabolismo , Biodegradação Ambiental , Petróleo/análise , Alcenos
4.
Environ Pollut ; 319: 121010, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36608732

RESUMO

First time, this study synthesized a magnetic-modified sludge biochar (MSBC) as an activator of peroxymonosulfate (PMS) to eliminate sulfamethoxazole (SMX). The removal efficiency of SMX reached 96.1% at t = 60 min by PMS/MSBC system. The larger surface area and magnetic Fe3O4 of MSBC surface enhanced its activation performance for PMS. The PMS decomposition, premixing and reactive oxygen species (ROS) identification experiments combined with Raman spectra analysis demonstrated that the degradation process was dominated by surface-bound radicals. The transformed products (TPs) of SMX and the main degradation pathways were identified and proposed. The ecotoxicity of all TPs was lower than that of SMX. The magnetic performance was beneficial for its reuse and the removal efficiency of SMX was 83.3% even after five reuse cycles. Solution pH, HCO3- and CO32- were the critical environmental factors affecting the degradation process. MSBC exhibited environmental safety for its low heavy metal leaching. PMS/MSBC system also performed excellent removal performance for SMX in real waters including drinking water (88.1%), lake water (84.3%), Yangtze River water (83.0%) and sewage effluent (70.2%). This study developed an efficient PMS activator for SMX degradation in various waters and provided a workable way to reuse and recycle municipal sludge.


Assuntos
Sulfametoxazol , Poluentes Químicos da Água , Sulfametoxazol/química , Esgotos , Poluentes Químicos da Água/análise , Peróxidos/química , Água , Fenômenos Magnéticos
5.
Environ Pollut ; 319: 121018, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36610649

RESUMO

The anaerobic granulation technology has been successfully applied full-scale for treating high-strength recalcitrant acrylic acid wastewater. This mini-review highlighted the recalcitrance of acrylic acid and its biological degradation pathways. And then, the full-scale practices using anaerobic granulation technology for acrylic wastewater treatment were outlined. The granules are proposed to provide barriers for high-concentration acrylic acid to the embedded anaerobic microbes, maintaining its high degradation rate without apparent substrate inhibition. Based on this proposal, the prospects of applying anaerobic granulation technology to handle a wide range of high-strength recalcitrant wastewaters, to improve the current process performances, and to recover renewable resources were delineated. The anaerobic granulation for high-strength recalcitrant wastewater treatment is an emergent technology that can assist in fulfilling the appeals of the circular bioeconomy of modern society.


Assuntos
Esgotos , Anaerobiose , Eliminação de Resíduos Líquidos , Reatores Biológicos
6.
Chemosphere ; 315: 137768, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36621689

RESUMO

A pilot-scale anaerobic-anoxic/nitrifying/induced crystallization (A2N-IC) process was established for phosphorus (P) recovery and nutrient removal from municipal wastewater with a treatment capacity of 80 m3d-1. Results show that the A2N-IC process can operate stably on a pilot scale; the recovery efficiency of influent P reached 62.2%, and the total P removal efficiency of the IC section was 65.4%. The IC section had little effect on the removal of chemical oxygen demand (COD) and nitrogen (N), and the P removal efficiency was improved. Soluble non-reactive P (sNRP) was the key factor affecting P recovery efficiency. Although P recovery increases the construction and maintenance costs, the process can be profitable if a market for P recovery products is established. To improve the P recovery efficiency, attention should be paid to the effects of sNRP and dissolved organic matter (DOM) on P recovery, and P-rich sludge should be considered.


Assuntos
Fósforo , Eliminação de Resíduos Líquidos , Humanos , Anaerobiose , Eliminação de Resíduos Líquidos/métodos , Cristalização , Reatores Biológicos , Esgotos/química , Hipóxia , Nitrogênio/análise
7.
Arch Microbiol ; 205(2): 76, 2023 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-36708390

RESUMO

Wastewater monitoring for SARS-CoV-2 has attracted considerable attention worldwide to complement the existing clinical-based surveillance system. In this study, we report our first successful attempt to prove the circulation of SARS-CoV-2 genes in Malaysian urban wastewater. A total of 18 wastewater samples were obtained from a regional sewage treatment plant that received municipal sewage between February 2021 and May 2021. Using the quantitative PCR assay targeting the E and RdRp genes of SARS-CoV-2, we confirmed that both genes were detected in the raw sewage, while no viral RNA was found in the treated sewage. We were also able to show that the trend of COVID-19 cases in Kuala Lumpur and Selangor was related to the changes in SARS-CoV-2 RNA levels in the wastewater samples. Overall, our study highlights that monitoring wastewater for SARS-CoV-2 should help local health professionals to obtain additional information on the rapid and silent circulation of infectious agents in communities at the regional level.


Assuntos
COVID-19 , Humanos , COVID-19/diagnóstico , COVID-19/epidemiologia , SARS-CoV-2/genética , Esgotos , RNA Viral/genética , Malásia/epidemiologia , Monitoramento Ambiental
8.
BMC Microbiol ; 23(1): 20, 2023 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-36658495

RESUMO

BACKGROUND: The floc is a characteristic of microbial aggregate growth, displaying cloudy suspensions in water. Floc formation has been demonstrated in a series of bacteria and the floc-forming bacteria play a crucial role in activated sludge (AS) process widely used for municipal sewage and industrial wastewater treatment over a century. It has been demonstrated that some exopolysaccharide biosynthesis genes and the sigma factor (sigma54 or rpoN) were required for floc forming in some bacteria. However, the mechanism underlying the floc formation stills need to be elucidated. RESULTS: In this study, we demonstrate that a TPR (Tetratricopeptide repeats) protein-encoding gene prsT is required for floc formation of Aquincola tertiaricarbonis RN12 and an upstream PEP-CTERM gene (designated pepA), regulated by RpoN1, is involved in its floc formation but not swarming motility and biofilm formation. Overexpression of PepA could rescue the floc-forming phenotype of the rpoN1 mutant by decreasing the released soluble exopolysaccharides and increasing the bound polymers. CONCLUSION: Our results indicate that the wide-spread PEP-CTERM proteins play an important role in the self-flocculation of bacterial cells and may be a component of extracellular polymeric substances required for floc-formation.


Assuntos
Burkholderiales , Esgotos , Esgotos/microbiologia , Bactérias/genética , Proteínas , Floculação
9.
Chemosphere ; 314: 137702, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36587913

RESUMO

This study aims to investigate the spatiotemporal trends and impact of COVID-19 lockdowns to the profile of physiochemical parameters in the influent of wastewater treatment plants (WWTPs) around Brisbane, Australia. One 24-hr composite influent sample was collected from 10 WWTPs and analyzed for a range of physiochemical parameters per week (i.e., chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), ammonia, volatile suspended solid (VSS)) and per month (i.e., Ni and Cr) from 2012 to 2020, including the period of COVID-19 lockdowns in the region. The catchments studied were urban, with a mix of domestic and industrial activities contributing towards the contaminant profile. Statistical analysis identified that industrial and commercial land use, as well as population size had a large impact to the parameter loads and profile. Per capita mass loads of Cr in one catchment were 100 times higher than in others from one industrial point source. TP demonstrated a potential monotonic decrease over time due to practical reduction policies that have been implemented for phosphorous content in household detergents, except for one catchment where trade waste from food manufacturing industries contributed to an overall increase of 6.9%/year TP. The COVID-19 lockdown (March-April 2020) posed different impact on different catchments, either decrease (7-61%) or increase (2-40%) of most parameter loads (e.g., COD, TOC, TN, TP, VSS, Ammonia), which was likely driven by catchment characteristics (i.e., the proportion of residential, commercial, and industrial land uses). This study enhances our understanding of spatiotemporal trend of contaminants in the catchments for further effective source control.


Assuntos
COVID-19 , Esgotos , Humanos , Amônia/análise , COVID-19/epidemiologia , Controle de Doenças Transmissíveis , Austrália , Nitrogênio/análise , Fósforo/análise , Eliminação de Resíduos Líquidos
10.
Chemosphere ; 314: 137703, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36587914

RESUMO

Pb0 in flue gas which is ubiquitous in the environment, poses a certain threat to human and ecology, but the study on EPS-dependent stabilization of lead to remove Pb0 from flue gas remains insufficient. In this investigation, the characteristics and heavy metals-binding ability of four EPS fractions were evaluated. The EPS were extracted from denitrifying membrane biofilm reactor (MBfR) and divided into slime EPS (S-EPS), loosely-bound EPS (LB-EPS), tightly-bound EPS (TB-EPS) and EPS in circulating flow (Y-EPS). The S, LB, TB-EPS related to Pb stabilization on biofilm need more attention. Compared to Pb-S-EPS (0.013 mg g-1) and Pb-LB-EPS (0.13 mg g-1), the Pb-TB-EPS (0.26 mg g-1) was mainly stable form of vapor Pb0, since TB-EPS's higher content (30.67-82.44 mg g-1 VSS), proteins (13.47-36.32 mg g-1 VSS) and polysaccharides (9.37-32.48 mg g-1 VSS) concentration. Particularly, proteins related ligands were more effective in S, LB, TB-EPS dependent adsorption of Pb, complexing with hydrophobic acid ligands further strengthened in TB-EPS adsorption. The Pb-EPS complex formed via binding with functional groups (such as O-H, N-H, C-H and CC) on EPS, also facilitated by loose structure of proteins. This study enlightens the researchers on the bio-treatment and EPS-dependent biosorption of Pb0 in flue gas in denitrifying MBfR.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Chumbo , Humanos , Matriz Extracelular de Substâncias Poliméricas/química , Chumbo/análise , Ligantes , Esgotos/química , Biofilmes , Proteínas/análise
11.
Water Environ Res ; 95(1): e10831, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36617440

RESUMO

Algal-bacterial granules or phototrophic granules (PGs) comprising phototrophic microorganisms and bacteria are explored in wastewater treatment for achieving both environmental and economic sustainability. This study describes development of PGs and their use in biological treatment of synthetic and real domestic wastewater (sewage) under natural daylight conditions and low organic loading rate (OLR). Development of PGs was sequentially recorded in a photobioreactor operated in photo-sequencing batch reactor (photo-SBR) mode at a low OLR of 1 kgCOD.m-3 .day-1 and the developed PGs was evaluated for treating synthetic wastewater and real municipal wastewater with 0.14 kg COD m-3 .day-1 . PGs formed in the photo-sequential batch reactor (SBR) were compact and dense and exhibited excellent settling properties. The removal efficiencies were determined to be up to 95%, 93%, 97%, 72%, and 88% for turbidity, COD, TOC, NH4 + -N, and NO2 - -N/NO3 - -N, respectively. Additionally, a reduction in total viable bacterial counts and fecal coliform bacteria up to 1.7 × 103 and 7.8 × 102 cfu.mL-1 , respectively, during treatment of real municipal wastewater was achieved. This study demonstrated cultivation of algal-bacterial granules or PGs and their application for treating real municipal wastewater under natural daylight and tropical climate conditions. Further studies are needed on understanding interactions among phototrophic, autotrophic, and heterotrophic microorganisms of complex algal-bacterial consortium for emerging applications in bioremediation and wastewater treatment. PRACTITIONER POINTS: Phototrophic granules (PGs) were cultivated from algal consortium and activated sludge inoculum in photo sequencing batch reactors. Granular photobioreactor was operated at low OLR of 1 kgCOD.m3 .day-1 for developing well-settling algal-bacterial granules. PGs were stable and showed efficient biological treatment of synthetic wastewater and real sewage. Removals for turbidity, pathogens, and ammonium were at 95%, 3-log, and 72%, respectively, from real sewage.


Assuntos
Purificação da Água , Esgotos/microbiologia , Eliminação de Resíduos Líquidos , Reatores Biológicos/microbiologia , Bactérias , Fotobiorreatores
12.
Environ Monit Assess ; 195(2): 287, 2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36626095

RESUMO

Identifying potential sources of pollution in tributaries and determining their contribution rates are critical to the treatment of water pollution in main streams. In this paper, we conducted a multivariate statistical analysis on the water quality data of 12 parameters for 3 years (2018-2020) at six sampling sites in the Laixi River to qualitatively identify potential pollution sources and quantitatively calculate the contribution rates to reveal the tributaries' pollution status. Spatio-temporal cluster analysis (CA) divided 12 months into two parts, corresponding to the lightly polluted season (LPS) and highly polluted season (HPS), and six sampling sites were divided into two regions, corresponding to the lightly polluted region (LPR) and highly polluted region (HPR). Principal component analysis (PCA) was used to determine the potential sources of contamination, identifying four and three potential factors in the LPS and HPS, respectively. The absolute principal component score-multiple linear regression (APCS-MLR) receptor model quantitatively analyzed the contribution rates of identified pollution sources, and the importance of the different pollution sources in LPS can be ranked as domestic sewage and industrial wastewater and breeding pollution (33.80%) > soil weathering (29.02%) > agricultural activities (20.95%) > natural influence (13.03%). HPS can be classified as agricultural cultivation (41.23%), domestic sewage and industrial wastewater and animal waste (33.19%), and natural variations (21.43%). Four potential sources were identified in LPR ranked as rural domestic sewage (31.01%) > agricultural pollution (26.82%) > industrial effluents and free-range livestock and poultry pollution (25.13%) > natural influence (14.82%). Three identified latent pollution sources in HPR were municipal sewage and industrial effluents (37.96%) > agricultural nonpoint sources and livestock and poultry wastewater (33.55%) > natural sources (25.23%). Using multivariate statistical tools to identify and quantify potential pollution sources, managers may be able to enhance water quality in tributary watersheds and develop future management plans.


Assuntos
Poluentes Químicos da Água , Qualidade da Água , Monitoramento Ambiental , Rios , Esgotos , Lipopolissacarídeos , Poluentes Químicos da Água/análise , Poluição da Água/análise , China
13.
Arch Virol ; 168(2): 38, 2023 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-36609610

RESUMO

A novel lytic Serratia liquefaciens phage, named vB_SlqM_MQ-4, was isolated from sewage. BLASTn analysis showed that the genome sequence of phage vB_SlqM_MQ-4 shared only 15% query coverage with that of Escherichia phage vB_EcoM-ep3, with 80.52% identity. Genomic analysis demonstrated that phage vB_SlqM_MQ-4 has a 43,534-bp dsDNA genome with 56% GC content and might be a member of a new genus in the order Caudoviricetes. Moreover, vB_SlqM_MQ-4 exhibited strong lytic performance with a short latent period (10 min) and a high burst size (267 PFU per cell) as well as a wide range of thermal (below 70 ℃) and pH tolerance (pH 4-12).


Assuntos
Bacteriófagos , Serratia liquefaciens , Bacteriófagos/genética , Serratia liquefaciens/genética , Genoma Viral , Genômica , Esgotos
14.
PeerJ ; 11: e14684, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36650829

RESUMO

When the wastewater volume exceeds the sewer pipe capacity during extreme rainfall events, untreated sewage discharges directly into rivers as combined sewer overflow (CSO). To compare the impacts of CSOs and stormwater on urban waterways, we assessed physicochemical water quality, the 16S rRNA gene-based bacterial community structure, and EcoPlate-based microbial functions during rainfall periods in an urban waterway before and after a stormwater storage pipe was commissioned. A temporal variation analysis showed that CSOs have significant impacts on microbial function and bacterial community structure, while their contributions to physicochemical parameters, bacterial abundance, and chlorophyll a were not confirmed. Heat map analysis showed that the impact of CSO on the waterway bacterial community structure was temporal and the bacterial community composition in CSO is distinct from that in sewers. Hierarchical clustering analysis revealed that the waterway physicochemical water qualities, bacterial community composition, and microbial community function were distinguishable from the upper reach of the river, rather than between CSO and stormwater. Changes in the relative abundance of tetracycline resistance (tet) genes-especially tet(M)-were observed after CSOs but did not coincide with changes in the microbial community composition, suggesting that the parameters affecting the microbial community composition and relative abundance of tet genes differ. After pipe implementation, however, stormwater did not contribute to the abundance of tet genes in the waterway. These results indicate that CSO-induced acute microbial disturbances in the urban waterway were alleviated by the implementation of a stormwater storage pipe and will support the efficiency of storage pipe operation for waterway management in urban areas.


Assuntos
Microbiota , RNA Ribossômico 16S/genética , Clorofila A , Esgotos , Microbiota/genética
15.
Water Environ Res ; 95(1): e10837, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36683357

RESUMO

Although the addition of excess sludge fermentation products to improve nutrient removal from sewage is cost-effective, its application has rarely been demonstrated. In this study, the external sludge was first collected and fermented under a sludge retention time of 10 days, then introduced into SBR with a 1:15 sewage ratio. The results revealed a gradual increase in the nitrite accumulation ratio to 34.7% in the SBR at the end of the oxic stage after 64 days of adding fermented sludge products. In addition, the average effluent total nitrogen and phosphorous decreased to 7.3 and 0.5 mg/L, corresponding to removal efficiencies of 86.7% and 95.5%, respectively. On the other hand, the use of the fermented sludge products as external organic carbon sources in the SBR increased the external sludge reduction ratio to 42.5%. High-throughput sequencing demonstrated that the increase in the endogenous denitrifier community, polyphosphate-accumulating organisms, and fermentation bacteria were the main factors contributing to the increase in nutrient removal and excess sludge reduction. The economic evaluation indicated that the operational cost of the pilot-scale system saves 0.011$/m3 of sewage treated. PRACTITIONER POINTS: Fermented sludge addition effectively enhanced nutrient removal in pilot-scale SBR. Average effluent TN and PO4 3- -P decreased to 7.3 and 0.5 mg/L, respectively. Highest external sludge reduction rate was 42.5% in pilot-scale reactor. Sewage treatment cost can save 0.011$/m3 under advanced nutrient removal.


Assuntos
Reatores Biológicos , Esgotos , Esgotos/microbiologia , Fermentação , Nitrogênio , Fósforo , Eliminação de Resíduos Líquidos/métodos
16.
Water Res ; 230: 119537, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36587520

RESUMO

The utilization of slowly-biodegradable organic matter (SBOM) to provide nitrite efficiently for anaerobic ammonia oxidation (anammox) process is an essential topic. High nitrite concentration without inhibition of exogenous organic matter is optimal condition for anammox process. In this study, hydrolytic fermentation (HF) of SBOM was applied to drive an endogenous partial denitrification (EPD) process (nitrate to nitrite) during an anaerobic-anoxic operation in a starch-fed system. With a limited production of exogenous organic matter (22.3 ± 4.9 mg COD/L), 79.0% of SBOM was transformed into poly-hydroxyalkanoates (PHA) through a pathway of simultaneous HF-absorption and endogenous polymer synthesis, corresponding to a hydrolytic fermentation ratio of 86.0%. A high nitrate to nitrite transformation ratio of 85.4% was achieved under an influent carbon to nitrogen ratio of 4.8. Denitrifying glycogen-accumulating organisms (DGAOs) was enriched from 0.6% to 10.9%, with an increase from 0.7 to 1.0 of nitrate reductase genes to nitrite reductase genes ratio. Subsequently, nitrate reduction rate was 5.6-fold higher than the nitrate reduction rate. A prominent migration of exogenous complete denitrification to EPD was accomplished. Furthermore, the starch-fed system exhibited performance with significant adaptability and stability in the presence of different SBOMs (dissolved protein and primary sludge). Therefore, the HF-EPD system achieved efficient nitrite production through EPD with the addition of various SBOMs, providing a potential alternative to anammox systems for the treatment of SBOM-rich wastewater.


Assuntos
Nitratos , Nitritos , Nitritos/metabolismo , Fermentação , Nitratos/metabolismo , Desnitrificação , Reatores Biológicos , Esgotos , Oxirredução , Nitrogênio
17.
Water Res ; 230: 119542, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36603308

RESUMO

The acidic (i.e., pH ∼5) activated sludge process is attracting attention because it enables stable nitrite accumulation and enhances sludge reduction and stabilization, compared to the conventional process at neutral pH. Here, this study examined the production and potential pathways of nitric oxide (NO) and nitrous oxide (N2O) during acidic sludge digestion. With continuous operation of a laboratory-scale aerobic digester at high dissolved oxygen concentration (DO>4 mg O2 L-1) and low pH (4.7±0.6), a significant amount of total nitrogen (TN) loss (i.e., 18.6±1.5% of TN in feed sludge) was detected. Notably, ∼40% of the removed TN was emitted as NO, with ∼8% as N2O. A series of batch assays were then designed to explain the observed TN loss under aerobic conditions. All assays were conducted with a low concentration of volatile solids (VS), i.e., VS<4.5 g L-1. This VS concentration is commensurate with the values commonly found in the aeration tanks of full-scale wastewater treatment systems, and thus no significant nitrogen loss should be expected when DO is controlled above 4 mg O2 L-1. However, nitrite disappeared at a significant rate (with the chemical decomposition of nitrite excluded), leading to NO production in the batch assays at pH 5. The nitrite reduction could be associated with endogenous microbial activities, e.g., nitrite detoxification. The significant NO production illustrates the importance of aerobic nitrite reduction during acidic aerobic sludge digestion, suggesting this process cannot be neglected in developing acidic activated sludge technology.


Assuntos
Óxido Nítrico , Nitritos , Esgotos/química , Reatores Biológicos , Eliminação de Resíduos Líquidos , Óxido Nitroso/metabolismo , Concentração de Íons de Hidrogênio , Nitrogênio
18.
Water Res ; 230: 119536, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36608525

RESUMO

Sustainable water pollution control requires understanding of historical trajectories and spatial characteristics of greenhouse gas (GHG) emissions from wastewater treatment plants (WWTPs), which remains inadequately studied. Here, we establish plant-level monthly operational emissions inventories of China's WWTPs in 2009-2019. We show that urban wastewater treatment has been enhanced with 80% more chemical oxygen demand being removed annually. However, this progress is associated with 180% more GHG emissions at the national level, up to 58.3 Mt CO2 eq in 2019. We found significant seasonality in GHG emissions. Increasing sludge yield and electricity intensity became primary drivers after 2015 because of stricter standards, causing GHG emissions increase 12.9 and 8.3% until 2019. GHG emissions from urban wastewater treatment show high spatial difference at province, city and plant levels, with different sludge disposal and energy mix approaches combined with different influent and effluent conditions in WWTPs across China. Stricter effluent standard resulted in similar GHG emissions growth pattern in cities. We argue WWTPs focus on resource recovery in developed areas and higher operational efficiency in developing areas.


Assuntos
Gases de Efeito Estufa , Purificação da Água , Eliminação de Resíduos Líquidos/métodos , Esgotos , Efeito Estufa , China
19.
Water Res ; 230: 119504, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36621275

RESUMO

The evolution of the climate in the future will probably lead to an increase in extreme rainfall events, particularly in the Mediterranean regions. This change in rainfall patterns will have impacts on combined sewer systems operation with a possible increase of spilled flows, leading to an increase of untreated water volumes released to the receiving water. Due to the impact of overflows on the water cycle, local authorities managing combined sewer systems are wondering about the extent of these changes and the possibility of taking it into account in stormwater management structure design. To do this, rainfall data with a fine time step are required to better master the shape of the hyetographs that are crucial to get a relevant rainfall/runoff relationship in an urban environment. However, there are currently no simulations of future rainfall series available at a time step compatible with the needs in urban drainage field. In this work, future rainfall time series with a fine time step are elaborated with the aim to be used in urban hydrology. The proposed approach is based on simulations results from five regional climate models in the framework of the Euro-Cordex program. It consists in a spatial downscaling step followed by a temporal disaggregation. The rainfall time series obtained are then used as input for a calibrated and validated hydrological model to investigate the evolution of annual CSO volumes and frequencies by 2100. The results show an increase of annual spilled volumes between 13% and 52% according to the considered climate model. This increase will most likely be a problem regarding compliance of sewer networks in line with the water framework directive, particularly the current French regulations. No clear trends were observed on the CSO frequencies. If there is a consensus for all the carried-out simulations to conclude that the CSO volumes will increase, we must remember that actual regional climate models suffer from limited spatial and temporal resolution and don't explicitly solve convection processes. Due to this point uncertainty concerning the evolution rate remains important particularly for intense rainfall episodes. New generations of climate models are needed to accurately predict intense episodes.


Assuntos
Mudança Climática , Ciclo Hidrológico , Água , Movimentos da Água , Fatores de Tempo , Chuva , Esgotos
20.
Water Res ; 230: 119561, 2023 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-36623383

RESUMO

Severe membrane fouling and the inability to remove/recover nitrogen and phosphorus are bottlenecks of anaerobic membrane bioreactors (AnMBRs) for large-scale application in wastewater treatment. Herein, an electrochemical AnMBR with a Mg anode-membrane module (electro-AnMBR) was built and showed good performance in terms of membrane fouling mitigation and nutrient recovery during sewage treatment. Compared with the traditional AnMBR, membrane fouling in the electro-AnMBR was reduced by up to 30%. The application of an electric field decreased the zeta potential, viscosity, and EPS concentration of the sludge-water liquor in the electro-AnMBR, which could improve the cake layer structure and thus enhance water permeability. Meanwhile, 26% of NH4+ and 48% of PO43- co-precipitated with Mg2+ generating from the sacrificial Mg anode and were recovered as struvite deposited onto cathode in the electro-AnMBR. Hydrogen evolution provided a relatively alkaline pH environment, resulting in struvite electrodeposition on the graphic cathode, which partly separated the formed struvite from the sludge with a purity of 77%. In the electro-AnMBR, the electrochemical reactions provided alkalinity and effectively inhibited anaerobic acidification. The applied voltage of 0.6 V reduced the relative abundance of methanosaeta, but increased that of methanosarcina, which is also beneficial for the membrane anti-fouling.


Assuntos
Incrustação Biológica , Esgotos , Eliminação de Resíduos Líquidos/métodos , Estruvita , Incrustação Biológica/prevenção & controle , Anaerobiose , Membranas Artificiais , Reatores Biológicos , Eletrodos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...