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1.
Chemosphere ; 283: 131278, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34467945

RESUMO

Production of MCFAs (Medium-chain fatty acids) from simple substrate (i.e., ethanol and acetate) and WAS with chain elongation microbiome was investigated in this study. The results showed that rapid production of MCFAs was observed when simple substrate was utilized. 1889 mg/L of caproate and 3434 mg/L of butyrate were achieved after 10 d's reaction. H2 proportion in the headspace could reach as high as 10.1% on day 8 and then declined quickly. However, when WAS was used, the bacterial consortia was not able to hydrolyze WAS efficiently, which resulted in poor MCFAs production performance. Presence of ethanol could improve the hydrolysis process to a limited degree, which resulted in solubilization of a small fraction of protein and carbohydrate. Around 33.8% and 36.9% of the total detected electrons on day 6 in the 50 mM and 100 mM tests were extracted from WAS respectively. Those results indicate that the chain elongation microbial consortia tended to receive electrons form ethanol directly other than the complex WAS.


Assuntos
Etanol , Esgotos , Elétrons , Ácidos Graxos , Fermentação
2.
Chemosphere ; 286(Pt 2): 131689, 2021 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-34352546

RESUMO

Quorum quenching (QQ), which disrupts bacterial communication and biofilm formation, could alleviate biofouling in MBR. QQ bio-stimulus possessing similar conserved moiety as the signal molecule could promote indigenous QQ bacteria, and thus successfully alleviate biofouling in MBR. However, efficient biostimulant has been barely explored for QQ enhancement in activated sludge system. This study extensively enumerated the potential QQ bio-stimuli, and examined their efficacy on QQ promotion for activated sludge. Moreover, the effect of the QQ consortia on fouling mitigation was also investigated. The results indicated that gamma-caprolactone (GCL), d-xylonic acid-1,4-lactone (XAL), gamma-heptalactone (GHL), urea, and acetamide proved effective in promoting AHLs inactivating activity of activated sludge. GCL, XAL, and GHL intensified the lactonase activity, while urea and acetamide augmented acylase activity. While coupled with beads entrapment, GCL consortia beads, XAL consortia beads, and urea consortia beads effectively disrupted quorum sensing (QS) and controlled membrane fouling in MBR. This work found out several optional bio-stimuli valid for tuning QQ in activated sludge system, and provided easily available and economical alternatives for QQ biostimulation, meanwhile the proposed QQ-MBR approach through QQ biostimulation and consortia entrapment also proved effective and practical.

3.
Bioresour Technol ; 337: 125452, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34186332

RESUMO

This first-attempt study illustrated the microbial cooperative interactions related to bioelectricity generation from the mixture of sludge fermentation liquid (SFL) and fruit waste extracts (FWEs) via microbial fuel cells (MFCs). The optimal output voltages of 0.65 V for SFL-MFCs, 0.51 V for FWEs-MFCs and 0.75 V for mixture-MFCs associated with bioelectricity conversion efficiencies of 1.061, 0.718 and 1.391 kWh/kg COD were reached, respectively. FWEs addition for substrates C/N ratio optimization contributed considerably to increase SFL-fed MFCs performance via triggering a higher microbial diversity, larger relatively abundance of functional genes and microbial synergistic interactions with genera enrichment of Clostridium, Alicycliphilus, Thermomonas, Geobacter, Paludibaculum, Pseudomonas, Taibaiella and Comamonas. Furthermore, a conceptual illustration of co-locating scenario of wastewater treatment plant(s), waste sludge in situ acidogenic fermentation, fruit waste collection/crushing station and MFC plant was proposed for the first time, which provided new thinking for future waste sludge treatment toward maximizing solid reduction and power recovery.


Assuntos
Fontes de Energia Bioelétrica , Eletricidade , Eletrodos , Fermentação , Frutas , Extratos Vegetais , Esgotos , Águas Residuárias
4.
Bioresour Technol ; 331: 124921, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33798852

RESUMO

This study proposed a cation-regulation strategy based on metal ion removal coupled Na+-regulation for enhancing anaerobic fermentation of waste activated sludge. The optimal treatment condition was: cation-exchange resin dosage of 1.75 g/g SS for 1-day treatment, followed by Na+-enhanced anaerobic fermentation at NaCl concentration of 20 g/L. The CER induced sludge solubilization and the Na+-regulation treatment triggered secondary hydrolysis of CER-solubilized sludge, causing remarkable sludge disintegration and extracellular polymeric substance (EPS) disruption. Numerous SCOD of 6588 mg/L (SCOD/TCOD = 40.6%) was released within 2 days, and the short-chain fatty acids (SCFAs) of 439.9 mg COD/g VSS was produced through 4-day anaerobic fermentation. More than 59% of the SCFAs was composed of acetate and propionate. Nitrogen-free organic matters (i.e. SCFAs and carbohydrates) accounted for 77.9% of SCOD, while considerable sludge solid reduction (51.6% of total VSS) was achievable, which was beneficial for fermentative liquid utilization and sludge disposal.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Esgotos , Anaerobiose , Cátions , Ácidos Graxos Voláteis , Fermentação , Concentração de Íons de Hidrogênio , Hidrólise
5.
Front Microbiol ; 11: 589222, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33162967

RESUMO

Previous studies have demonstrated that sludge hydrolysis and short-chain fatty acids (SCFAs) production were improved through NaCl assistant anaerobic fermentation. However, the effect of NaCl concentrations on hydrolase activity and microbial community structure was rarely reported. In this study, it was found that α-glucosidase activity and some carbohydrate-degrading bacteria were inhibited in NaCl tests, owing to their vulnerability to high NaCl concentration. Correspondingly, the microbial community richness and diversity were reduced compared with the control test, while the evenness was not affected by NaCl concentration. By contrast, the protease activity was increased in the presence of NaCl and reached the highest activity at the NaCl concentration of 20 g/L. The protein-degrading and SCFAs-producing bacteria (e.g., Clostridium algidicarnis and Proteiniclasticum) were enriched in the presence of NaCl, which were salt-tolerant.

6.
Water Res ; 187: 116452, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33002775

RESUMO

Fluorescence spectroscopy has been suggested as a promising online monitoring technique in water and wastewater treatment processes due to its high sensitivity and selectivity. However, a pre-filtration is still indispensable in fluorescence measurement for removing ubiquitous particles and flocs in real samples to eliminate the strong light scattering that could attenuate fluorescence detection significantly. This study proposed a front-face fluorescence spectroscopy, which could characterize the liquid sample with suspended solids directly without pre-filtration. Front-face excitation-emission matrix (FF-EEM) coupled with parallel factor (PARAFAC) analysis was used for analyzing fluorescence components and to probe coagulation of secondary effluent and fouling in the subsequent ultrafiltration (UF), and conventional right-angle fluorescence EEM (RA-EEM) was also compared. The results showed that FF-EEM was less susceptible to turbidity (induced by standard particles) in the secondary effluent compared to RA-EEM. FF-EEM could successfully measure dissolved fluorophores in coagulated suspension without pre-filtration, while conventional RA-EEM was undermined significantly due to the existing flocs. FF-EEM coupled with PARAFAC could accurately probe dissolved organic matter and fouling in coagulation- UF wastewater reclamation processes. Therefore, it was demonstrated that this front-face fluorescence without any sample preparation step might be highly promising in real-time online fluorescence monitoring in multi water and wastewater treatment processes.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Análise Fatorial , Filtração , Substâncias Húmicas/análise , Espectrometria de Fluorescência , Ultrafiltração , Águas Residuárias , Poluentes Químicos da Água/análise
7.
Membranes (Basel) ; 10(9)2020 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-32957473

RESUMO

To understand impacts of organic adhesion on membrane fouling, ultrafiltration (UF) membrane fouling by dissolved natural organic matter (NOM) was investigated in the presence of background cations (Na+ and Ca2+) at typical concentrations in surface water. Moreover, NOM adhesion on the UF membrane was investigated using atomic force microscopy (AFM) with colloidal probes and a quartz crystal microbalance with dissipation monitoring (QCM-D). The results indicated that the adhesion forces at the NOM-membrane interface increased in the presence of background cations, particularly Ca2+, and that the amount of adhered NOM increased due to reduced electrostatic repulsion. However, the membrane permeability was almost not affected by background cations in the pore blocking-dominated phase but was aggravated to some extent in the cake filtration-governed phase. More importantly, the irreversible NOM fouling was not correlated with the amount of adhered NOM. The assumption for membrane autopsies is doubtful that retained or adsorbed organic materials are necessarily a primary cause of membrane fouling, particularly the irreversible fouling.

8.
Bioresour Technol ; 318: 123953, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32927314

RESUMO

This study reported a "treating waste by waste" strategy to dispose waste activated sludge (WAS), i.e. reverse osmosis (RO) brine-enhanced anaerobic fermentation. RO brine was hazardous by-product from seawater desalination process, which contains numerous Na+. After 4-day RO brine-enhanced anaerobic fermentation at Na+ concentration of 0.33 mol/L, 5.0 g/L VSS reduction (37.9% of VSS) was achievable, leading to considerable soluble chemical oxygen demand (SCOD) release of 349.6 mg/g VSS. Acetic acid was predominant component in SCOD (31.1%), followed by propionic, butyric, valeric acids and proteins (14.0-17.6%). Sludge solubilization and SCOD composition in the enhanced anaerobic fermentation with RO brine and NaCl agent were similar, whereas less nutrient release and extracellular polymeric substance (EPS) disruption were achieved by RO brine, attributing to the Ca2+&Mg2+-caused skeleton strengthening on EPS matrix. Such RO brine-based strategy provided environmental and economic benefits, e.g. none chemical consumption, synchronous disposal of WAS and RO brine.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Esgotos , Anaerobiose , Fermentação , Concentração de Íons de Hidrogênio , Osmose , Sais
9.
Bioresour Technol ; 312: 123397, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32526667

RESUMO

This study reported a novel pretreatment approach with combination of alkaline protease (AP) and pH 10 for enhancing short-chain fatty acids (SCFAs) production from waste activated sludge (WAS). Through the AP-based pretreatment, WAS flocs were disintegrated with cell lysis, leading to release of biodegradable organic matters. At the external AP dosage of 5%, SCOD of 5363.7 mg/L (SCOD/TCOD = 32.5%) was achievable after 2-h pretreatment. More than 66% of SCOD was composed of proteins and carbohydrates. Considerable SCFAs of 607 mg COD/g VSS was produced over a short-term anaerobic fermentation of 3 days, which was 5.4 times higher than that in the control. Acetic and propionic acids accounted for 74.1% of the SCFAs. The AP-based approach increased endogenous protease and α-glucosidase activities, facilitating biodegradation of dissolved organic matters and SCFAs production. Such approach is promising for WAS disposal and carbon recovery, the produced SCFAs might supply 60% of carbon gap in wastewater.


Assuntos
Ácidos Graxos Voláteis , Esgotos , Anaerobiose , Proteínas de Bactérias , Endopeptidases , Fermentação , Concentração de Íons de Hidrogênio
10.
Bioresour Technol ; 312: 123303, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32521466

RESUMO

This study developed an economical approach for enhancing short-chain fatty acids (SCFAs) production from waste activated sludge (WAS) by NaCl assistant anaerobic fermentation. With NaCl addition at 20 g/L, sludge disintegration with extracellular polymeric substance (EPS) disruption and cell lysis were induced owing to the attack of osmotic pressure, which facilitated WAS solubilization with release of biodegradable organic matters. The SCOD sharply increased to 4092 mg/L (SCOD/TCOD = 23.9%) after 2-day hydrolysis, against 1462 mg/L in the control. After 4-day anaerobic fermentation, considerable SCFAs production of 288.2 mg COD/g VSS was achievable. More than 60% of the SCFAs was composed of acetic and propionic acids. The feasibility of bio-electrogenesis in microbial fuel cell (MFC) utilizing fermentative liquid was assessed. As such, the produced SCFAs could be consumed with energy recovery, thereby the used NaCl was reusable, which created environmental and economic benefits, e.g. reduced NaCl consumption and cost, negligible residual NaCl.


Assuntos
Esgotos , Cloreto de Sódio , Anaerobiose , Matriz Extracelular de Substâncias Poliméricas , Ácidos Graxos Voláteis , Estudos de Viabilidade , Fermentação , Concentração de Íons de Hidrogênio , Hidrólise
11.
Bioresour Technol ; 313: 123659, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32554151

RESUMO

This study reported the NaCl-enhanced anaerobic fermentation with cation-exchange resin regeneration waste liquid (CRWL) as alternative NaCl source for waste activated sludge (WAS) disposal and carbon recovery. Through 4-day CRWL-enhanced anaerobic fermentation at Na+ concentration of 0.34 mol/L, the Na+-caused sludge disintegration triggered numerous release of dissolved organic matters (DOMs), i.e. 371.6 mg/g VSS, with composition distribution: acetic acid (28.2%) > butyric acid (16.1%) ≈ valeric acid (17.8%) ≈ proteins (16.4%) > propionic acid (14.4%) > unknown (3.2%) > carbohydrates (3.9%). Satisfying chemical conditioning performance for the fermented sludge was observed at the FeCl3 dosage of 0.3 g/g DS, attributing to the roles of double-layer compression and electric neutralization. The capillary suction time (CST) and sludge cake moisture content were decreased to 60.3 s and 75.1%, against those of 607 s and 93.5% before conditioning, respectively. Such "treating waste by waste" strategy could provide numerous environmental and economic benefits.


Assuntos
Esgotos , Cloreto de Sódio , Anaerobiose , Cátions , Ácidos Graxos Voláteis , Fermentação , Eliminação de Resíduos Líquidos
12.
J Hazard Mater ; 398: 122930, 2020 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-32464562

RESUMO

The correlation of the lack in multivalent cations with hydrolase activity and microbial community in anaerobic fermentation of waste activated sludge was investigated in this study. It was demonstrated that considerable solid phase reduction of 41 % (7.87 g/L) was achievable through a cation exchange resin-enhanced anaerobic fermentation of 4 days. The protease and α-glucosidase, especially α-glucosidase, were easily influenced by a lack in multivalent cations. Furthermore, species abundance and diversity of microbial community gradually decreased. Meanwhile, the bacteria community structure presented obvious dynamic shifts. Ruminococcaceae_UCG_009, Bacteroides and Macellibacteroides responsible for organic matter biodegradation and SCFAs production became dominant bacteria in cation exchange resin-enhanced anaerobic fermentation, which was less influenced by the lack in multivalent cations, while the SCFA consumers (e.g. methanogens) were inhibited with reduced abundances due to their susceptibility to the lack in multivalent cations. Redundancy analysis revealed that the lack in multivalent cations were responsible for the microbial community evolution, which was proved by the high Grey relational coefficients (0.747-0.820) and significant negative Spearman coefficients (-0.5798 to -0.9429) between multivalent cation and microbial community. Obviously, the cation exchange resin-induced removal of multivalent cations reduced enzyme activity and modified microbial community structure, which created a beneficial environment for enhancing anaerobic fermentation.


Assuntos
Microbiota , Esgotos , Anaerobiose , Resinas de Troca de Cátion , Cátions , Ácidos Graxos Voláteis , Fermentação , Hidrolases
13.
Sci Total Environ ; 712: 136562, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-32050387

RESUMO

Granular sludge usually takes extracellular polymers (EPS) as matrices for colonizing microorganisms and maintaining structural stability. However, the low strength of EPS threatens the disintegration of granules, especially under low hydraulic shear force. To accelerate the formation and enhance the stability of granules, micro-sized melamine (ME) sponges (RA) and polyurethane (PU) sponges (RB) were screened out as matrix substitutes for developing aerobic granular biofilm (AGB) in this study. The superficial gas velocity was 0.8 cm s-1. Both reactors achieved over 95% ammonium nitrogen removal efficiency within 10 days. During stabilization period, the chemical oxygen demand, total nitrogen and total phosphorus removal efficiencies were 90.5%, 70% and 95% in RA and 87.8%, 83% and 88% in RB, respectively. Confocal laser scanning microscopy (CLSM) detection revealed that ß-polysaccharide was more concentrated in the outer layer in PU-AGB but uniformly dispersed in ME-AGB. The denitrifying phosphorus accumulating organisms (Flavobacterium) was dominant in RA, while the denitrifying glycogen accumulating organisms (Candidatus_Competibacter) was dominant in RB. Fluorescence in situ hybridization (FISH) analysis indicated that the microbial distribution in ME-AGB was relatively uniform, while there was a significant migration of functional microorganisms in PU-AGB. The super-hydrophilicity of ME and the high hydrophobicity of PU may be the main reasons for these differences. Overall, this study indicated that ME sponge is a more suitable material for supporting AGB than PU sponge.


Assuntos
Microbiota , Esgotos , Aerobiose , Reatores Biológicos , Hibridização in Situ Fluorescente , Nitrogênio , Fósforo , Eliminação de Resíduos Líquidos
14.
Bioresour Technol ; 302: 122870, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32004809

RESUMO

This study reported an efficient and green approach towards facilitating hydrolysis of waste activated sludge (WAS) using cation exchange resin (CER) as a recyclable additive. Through CER-mediated removal of multivalent cations, WAS flocs were disintegrated into small particles with extracellular polymeric substance (EPS) solubilization. At CER dosage of 1.75 g/g SS, SCOD increased to 2579 mg/L (SCOD/TCOD = 15.9%) after 8-h hydrolysis. Afterwards, CER displayed further sludge hydrolysis performance lasting 2 days, i.e. SCOD/TCOD = 34.2%. Meanwhile, proteins, carbohydrates and other organics in dissolved organic matters (DOMs) were major contributors for volatile fatty acids (VFAs) accumulation, with composition percentage: VFAs (58.9%) > proteins (21.8%) > other organics (8.8%) > humic acids (5.9%) > carbohydrates (4.4%). The biodegradable tryptophan-like and tyrosine-like proteins were major proteins, while other organics included amino acids, aliphatic and metabolic intermediates. More than 85.2% of DOMs were easily biodegradable. Moreover, CER-induced hydrolysis modified microbial community structure through inhibiting VFAs-utilizing microbes, while hydrolytic-acidogenic bacteria were enriched, responsible for DOMs biodegradation.


Assuntos
Microbiota , Esgotos , Resinas de Troca de Cátion , Matriz Extracelular de Substâncias Poliméricas , Ácidos Graxos Voláteis , Hidrólise
15.
Sci Total Environ ; 698: 134311, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31783455

RESUMO

Low temperature is a great challenge for the biological treatment of wastewater. In this study, the rapid start-up of aerobic granular biofilm (AGF) reactor was realized by adding micro-sized polyurethane (PU) sponges as matrices at 10 °C. The results showed that the granulation process of AGF was different from that of traditional aerobic granular sludge and biofilms, which was formed by using the sludge intercepted in PU matrix instead of sponge skeletons as granulation carriers. During the 5-month operation period, stable pollutants removal performance was achieved within 70 days, besides, the corresponding ammonium, total nitrogen, and total phosphorus removal efficiencies were 98%, 70%, and 95%, respectively. The addition of PU matrices inhibited the growth of filamentous bacteria and provided support for high structural stability of AGF. With the operation of the reactor, the relative abundance of traditional denitrifying bacteria (genera Thauera and Acidovorax, etc.) decreased gradually, and the putative denitrifying phosphorus accumulating genus, Dechloromonas, occupied a dominant position in the system. This experiment showed that AGF system could be successfully started-up and operated with efficient pollutants removal performance under low temperature when using micro-sized PU sponges as matrices.


Assuntos
Biofilmes , Temperatura , Eliminação de Resíduos Líquidos/métodos , Compostos de Amônio , Reatores Biológicos/microbiologia , Microbiota , Nitrogênio , Fósforo
16.
J Environ Manage ; 232: 321-329, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30496961

RESUMO

In this study, the dynamic changes in fungal biodiversity, community structure, fungal associations and functional characteristics were investigated in the biodrying of storage sludge and beer lees by using high throughput sequencing, network and correlation matrix analyses, and FUNGuild database. Additionally, a hypothetical model was provided to better understand the biodrying system. The results showed that fungal diversity decreased after biodrying, while community richness increased in the mesophilic stage and decreased as biodrying progressed. Fungal communities differed in different stages of the biodrying process. Ascomycota and Basidiomycota were the dominant phyla throughout the biodrying process, while Pichia was the dominant genus in the thermophilic stage. Network and correlation matrix analyses provided useful tools for insight into the fungal interactions, allowing us to propose a conceptual model of how succession in fungal associations regulates the dynamics of biodrying systems. Biodrying treatment had a significant effect on fungal trophic modes, with most pathogenic fungi fading away over the process, illustrating that biodrying is an effective bio-treatment method to eliminate pathogenic fungi. These findings provide information that elucidates the fungal interactions and functional characteristics during the biodrying process.


Assuntos
Ascomicetos , Basidiomycota , Cerveja , Biodiversidade , Fungos , Esgotos
17.
Bioresour Technol ; 274: 225-231, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30508749

RESUMO

This study developed an integrated approach for electric energy harvest/resource reuse from waste activated sludge (WAS) pretreated by enzymolysis based on anaerobic fermentation and microbial fuel cells (MFCs). WAS solubilization by the 3-h enzymatic pretreatment (a blend of hydrolytic enzymes caused over 5300 mg/L soluble COD release) prompted volatile fatty acid (VFA) production with 3580 mg COD/L after 10-d fermentation. After solid-liquid separation, fermentation liquid with high VFA content was fed into MFCs for electric energy production, while solid residues were used for making building materials (such as blended cements). Results showed that the electricity conversion efficiency of fermentation liquid (VFA) reached 1.254 kW h/kg COD with over 90% organics removal and solid residues could be consumed potentially as qualified substitutes for producing cements. As such, this study may provide some new thinking on future WAS management towards electricity harvest/resource reuse with zero secondary wastes discharge.


Assuntos
Esgotos , Gerenciamento de Resíduos/métodos , Fontes de Energia Bioelétrica , Eletricidade , Ácidos Graxos Voláteis/biossíntese , Fermentação , Hidrólise
18.
Water Sci Technol ; 78(7): 1466-1475, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30427786

RESUMO

Adsorption is an important step during the migration of ammonium from the aqueous phase to biomass in biological nitrogen removal processes. A deeper understanding of the adsorption mechanisms is encouraged in constructing nitrogen conversion models. In this study, the ammonium adsorption in aerobic granular sludge was investigated at different conditions. Analysis of kinetic data indicated that ammonium adsorption was a fast process and followed pseudo-second-order kinetics (adsorption rate constant k2 was between 0.031 and 0.065 g/(mg · min)). The maximum adsorption capacity and half saturation constant KL in the Langmuir isotherm model were 4.95 mgNH4 +-N/g total suspended solids and 0.0126 L/mg, respectively. Effects of environmental conditions such as temperature, pH and competitive cations were also estimated. The optimum pH was 7 and the effects of competitive cations were in the order Ca2+ > Mg2+ > K+ > Na+. Values of thermodynamic parameters (ΔHƟ = -14.697 kJ/mol, ΔSƟ = -6.65 J/(mol · K)) indicated that the adsorption process was spontaneous and exothermic. Desorption tests showed that the process was reversible and low temperature had a negative effect on ammonium desorption. These findings could be useful for completing the mathematical model of the nitrogen removal process in bioreactors.


Assuntos
Compostos de Amônio/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Adsorção , Compostos de Amônio/análise , Temperatura Alta , Concentração de Íons de Hidrogênio , Cinética , Esgotos , Termodinâmica , Poluentes Químicos da Água/análise
19.
J Environ Sci (China) ; 74: 177-185, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30340671

RESUMO

Corrosion, one of the most common problems of metal pipe for water supply, generally leads to poor water quality, bacteria proliferation, water capacity decrease and other problems. As microorganisms affect corrosion by changing the characteristics of metal surface, the mechanism of microbial corrosion still remains unclear. The corrosion behavior of ductile cast iron is implemented in the dynamic flow and static conditions, in which variations of water quality and microbial community are analyzed in details. The results show that if the corrosion rate of ductile cast iron decreases, the corrosion of cast iron will result in a lower DO and a higher total iron in bulk water. The number of microorganisms is not a decisive factor of corrosion, even though the counts of bacteria had a close relationship with DO. On the basis of the detection of the 10 kinds of nitrate-reducing bacteria by Miseq sequencing, NRB of the biofilm biomass accounts for 18.3% on the 30th day and 20.5% on the 55th day. Even though aerobic NRBs go into the biofilm later than the facultative anaerobic NRBs, the growth of the anaerobic NRBs is not affected.


Assuntos
Bactérias/isolamento & purificação , Ferro/química , Microbiologia da Água , Abastecimento de Água , Corrosão , Qualidade da Água
20.
Chemosphere ; 211: 1219-1227, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30223338

RESUMO

Aerobic granules were successfully cultivated at 10 °C with relatively low strength substrate. Stable granules coexisted with the batt-like sludge (BLS) were obtained in 60 days. After removing the BLS, nutrient removal performance was greatly improved and stable removal efficiencies of 99% phosphorous, 98% ammonia and 60% TN were achieved. The bacterial community structure revealed that it was an unclassified-Comamonadaceae genus dominant in the BLS, which represented for low relative abundance in mature granules. Overgrowth of unclassified-Comamonadaceae genus was considered to be the key factor for inhibiting the performance of granules. The final configuration of granules was dominated by DPAO genus Flavobacterium and polysaccharide nutritional genus Chryseolinea. This study showed that stable aerobic granules with superior performance under low temperature could be successfully cultivated by sieving out the BLS.


Assuntos
Aerobiose , Temperatura Baixa , Esgotos/química , Amônia/isolamento & purificação , Reatores Biológicos/microbiologia , Filtração , Fósforo/isolamento & purificação , Esgotos/microbiologia , Eliminação de Resíduos Líquidos
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