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1.
J Environ Sci (China) ; 106: 194-203, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34210435

RESUMO

Aerobic granule is a special microbial aggregate associated with biofilm structure. The formation of aerobic granular sludge is primarily depending on its bacterial community and relevant microbiological properties. In this experiment, a strain with high microbial attachment was isolated from aerobic granular sludge, and the detailed characteristics were examined. Its high attachment ability could reach 2.34 (OD600nm), while other low attachment values were only around 0.06-0.32, which indicated a big variation among the different bacteria. The strain exhibited a very special morphology with many fibric fingers under SEM observation. A distinctive behaviour was to form a spherical particle by themselves, which would be very beneficial for the formation and development of granular sludge. The EPS measurement showed that its PN content was higher than low attachment bacteria, and 3D-EEM confirmed that there were some different components. Based on the 16S rRNA analysis, it was identified to mostly belong to Stenotrophomonas. Its augmentation to particle sludge cultivation demonstrated that the strain could significantly promote the formation of aerobic granule. Conclusively, it was strongly suggested that it might be used as a good and potential model strain or chassis organism for the aerobic granular sludge formation and development.


Assuntos
Bactérias , Esgotos , Aerobiose , Bactérias/genética , Biofilmes , Reatores Biológicos , RNA Ribossômico 16S/genética , Eliminação de Resíduos Líquidos
2.
J Environ Sci (China) ; 106: 83-96, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34210442

RESUMO

In this work, we employed waste activated sludge (WAS) as carbon source to prepare ultrahigh specific surface area (SSA) biopolymers-based carbons (BBCs) through alkali (KOH) treatment coupled to pyrolysis strategy. Before the pyrolysis process, the involvement of KOH made a great recovery of soluble biopolymers from WAS, resulting in highly-efficient catalytic pyrolysis. The Brunner-Emmett-Teller and pore volume of BBCs prepared at 800°C (BBC800) reached the maximum at 2633.89 m2·g-1 and 2.919 m3·g-1, respectively. X-ray photoelectron spectroscopy suggested that aromatic carbon in the form of C=C was the dominant fraction of C element in BBCs. The N element in BBCs were composed of pyrrolic nitrogen and pyridinic nitrogen at 700°C, while a new graphitic nitrogen appeared over 800°C. As a refractory pollutant of wastewater treatment plants, tetracycline (TC) was selected to evaluate adsorption performance of BBCs. The adsorption behavior of BBCs towards TC was conformed to the pseudo-second-order kinetic and the Langmuir models, signifying that chemisorption of monolayers was dominant in TC adsorption. The adsorption capacity of BBC800 reached the maximum at 877.19 mg·g-1 for 90 min at 298 K. Thermodynamic analysis indicated that the adsorption process was endothermic and spontaneous. Hydrogen bonding and π-π stacking interaction were mainly responsible for TC adsorption, and interfacial diffusion was the main rate-control step in adsorption process. The presence of soluble microbial products (SMPs) enhanced TC removal. This work provided a novel strategy to prepare bio-carbon with ultrahigh SSA using WAS for highly-efficient removal of organic pollutants.


Assuntos
Esgotos , Poluentes Químicos da Água , Adsorção , Álcalis , Biopolímeros , Carbono , Carvão Vegetal , Cinética , Pirólise , Poluentes Químicos da Água/análise
3.
Environ Monit Assess ; 193(7): 455, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34212216

RESUMO

Coastal water quality assessment is important to maintain a healthy environment for various uses including fisheries and recreation. Microbial populations are used as biological indicators of contamination to monitor water quality and are considered by the government to be one of the critical features for issuing safety guidelines. Different bacterial groups (pathogenic, vibrio and faecal) from five major recreational beaches of Chennai, India, were monitored for the assessment of coastal water quality. Faecal coliforms (FC) were high at all the beaches, with up to 4.2 × 105 CFU/mL and exceeding the normal standard limits of 100 CFU/100 mL set by the Central Pollution Control Board (CPCB) of India. Rainfall was found to have a role in the variability and distribution of indicator and pathogenic bacteria. The seasonal dry period witnessed elevated FC, while dilution in the wet period reduced Escherichia coli-like organisms (ECLO). High microbial counts were detected near the beach situated close to the river mouth, mainly due to discharges of untreated domestic sewage and industrial wastes. Similarly, the biological oxygen demand (BOD) was also high, 0.32 to 10.32 mg/L. Dissolved inorganic nitrogen (DIN) ranged from 2.21 to 134.53 µmol/L and inorganic phosphate (IP) ranged from 0 to 57.53 µmol/L. These values indicated the presence of significant untreated sewage in the coastal water. This study revealed that Chennai coastal waters carry high levels of faecal and pathogenic bacteria, detrimental for recreational and other contact activities. The quantitative and qualitative analyses will be useful for modelling and prediction of coastal water quality and management of other recreational beaches in India.


Assuntos
Esgotos , Microbiologia da Água , Bactérias , Praias , Monitoramento Ambiental , Fezes , Índia
4.
Artigo em Inglês | MEDLINE | ID: mdl-34207348

RESUMO

The sustainable economy framework imposes the adoption of new ways for waste reuse and recycling. In this context, this paper proposes a new alternative to obtain glass fertilizers (agriglasses) by reusing two cheap and easily available wastes, wood ash and manganese rich sludge resulting from drinking water treatment processes for groundwater sources. Glasses were obtained using different amounts of wastes together with (NH4)2HPO4 and K2CO3 as raw materials. The P-K-Mn nutrient solubilization from the obtained glasses was investigated using a citric acid solution. The kinetics of the leaching process was studied after 1, 7, 14, 21 and 28 days, respectively. The intraparticle diffusion model was used to interpret kinetic data. Two distinct stages of the ion leaching process were recorded for all of the studied compositions: first through intraparticle diffusion (the rate-controlling stage) and second through diffusion through the particle-medium interface. The fertilization effect of the obtained agriglasses was studied on a barley crop. The specific plant growth parameters of germination percentage, average plant height, biomass and relative growth rate were determinate. The positive impact of the agriglasses upon the plants biomass and relative growth rate was highlighted. The effects of agriglasses can be tuned through glass compositions that affect the solubility of the nutrients.


Assuntos
Fertilizantes , Esgotos , Biomassa , Fertilizantes/análise , Nutrientes , Reciclagem
5.
Artigo em Inglês | MEDLINE | ID: mdl-34205161

RESUMO

Polyvinyl alcohol (PVA) is a water-soluble plastic commercially used in laundry and dish detergent pods (LDPs) for which a complete understanding of its fate in the environment and subsequent consequences is lacking. The objective of this study was to estimate the US nationwide emissions of PVA resulting from domestic use of LDPs, corroborated by a nationwide, online consumer survey and a literature review of its fate within conventional wastewater treatment plants (WWTPs). Peer-reviewed publications focusing on the degradation of PVA in critical processes of WWTPs were shortlisted as a part of the literature review, and subsequent degradation data was extracted and applied to a model with a set of assumptions. Survey and model results estimated that approximately 17,200 ± 5000 metric ton units per year (mtu/yr) of PVA are used from LDPs in the US, with 10,500 ± 3000 mtu/yr reaching WWTPs. Literature review data, when incorporated into our model, resulted in ~61% of PVA ending up in the environment via the sludge route and ~15.7% via the aqueous phase. PVA presence in the environment, regardless of its matrix, is a threat to the ecosystem due to the potential mobilization of heavy metals and other hydrophilic contaminants.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Ecossistema , Álcool de Polivinil , Esgotos , Águas Residuárias , Poluentes Químicos da Água/análise
6.
Artigo em Inglês | MEDLINE | ID: mdl-34241591

RESUMO

A Gram-stain-positive, rod-shaped, strictly aerobic bacterial strain (Y6T) was isolated from a sewage sludge sample collected from a fisheries processing factory in Zhoushan, Zhejiang Province, PR China. The growth range of NaCl concentration was 0-6.0 % (w/v), with an optimum at 3.0 % (w/v). The temperature range for growth was 10-42 °C, with an optimum at 37 °C. The pH range for growth was pH 7.0-10.0, with an optimum at pH 9.0. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain Y6T belonged to the genus Nocardioides and showed the highest sequence similarity of 97.8 % to Nocardioides jishulii dk3136T. The average nucleotide identity and in silico DNA-DNA hybridization values between strain Y6T and the reference strains were 76.9-81.2 % and 20.6-23.6 %, respectively. Chemotaxonomic analysis indicated that the sole respiratory quinone was MK-8(H4) and the predominant cellular fatty acids were iso-C16 : 0, 10-methyl-C17 : 0 and C18 : 1 ω9c. The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, four unidentified phospholipids, three unidentified aminolipids and five unidentified lipids. The peptidoglycan was ll-2,6-diaminopimelic acid. On the basis of the phenotypic, genotypic, phylogenetic and chemotaxonomic features, strain Y6T is considered to represent a novel species, for which the name Nocardioides malaquae sp. nov. is proposed. The type strain is Y6T (=KCTC 49504T=MCCC 1K04765T).


Assuntos
Pesqueiros , Nocardioides/classificação , Filogenia , Esgotos/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Nocardioides/isolamento & purificação , Hibridização de Ácido Nucleico , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
7.
Chemosphere ; 281: 130894, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34289603

RESUMO

Long-term storage of aerobic granular sludge (AGS) may lead to granule inactivation and disintegration. Granule recovery in both structure and activity is important for scale-up and stability of AGS, but information about the structure recovery of stored AGS is limited. In addition, whether short-term exogenous N-acyl-homoserine lactones (AHLs) regulations could accelerate the granule recovery and sustain positive effects on AGS is unknown. Herein, the recovery of 33-month stored AGS was performed in three reactors for 38 days (phase I) at different exogenous AHLs concentrations (0, 50 and 500 nM of AHL-mixtures in R0, R1 and R2, respectively) and for an extended 45 days without exogenous AHLs (phase II). Results demonstrated successful recovery of disintegrated AGS in all reactors, although it was relatively time-consuming in R0. The treatment performance was similar among the reactors and steady-state removal of COD (90%) and NH4+-N (94%) could be recovered within 7 and 21 days, respectively. However, exogenous AHLs regulation (especially in R1) obviously accelerated bioactivity recovery of heterotrophs and nitrifiers and improved granule characteristics, including biomass, density, hydrophobicity and extracellular polymeric substance (EPS). During phase II, sustainable positive effects remained in R1, but granule characteristics deteriorated in R2. The abundance of functional genera Thauera, Nitrosomonas and Candidatus_Nitrotoga, contributed to the rapid recovery and helped maintain the structure and activity of AGS. The predictive functional profiling of bacterial communities also demonstrated sustainably higher activities of metabolism, growth and signal sensing under exogenous AHLs regulation at an appropriate content.


Assuntos
Acil-Butirolactonas , Esgotos , Bactérias , Reatores Biológicos , Matriz Extracelular de Substâncias Poliméricas , Percepção de Quorum
8.
Chemosphere ; 281: 130899, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34289605

RESUMO

The impacts of the influent type in wastewater treatment plants (WWTPs) on the distribution patterns of the microbial community and functional characteristics were investigated. The obtained results indicated that the influent types exhibited evident influences on the microbial distribution patterns. The diversity and richness of functional microbes in HI-WWTP (with a ratio of >30% industrial wastewater in influents) were evidently decreased compared with those in HM- (with 70-90% municipal wastewater in influents) and M-WWTPs (with >90% municipal wastewater in influents). The core functional bacteria included denitrifiers, anaerobic fermentation bacteria (AFB), organic degrading bacteria (ODB), phosphorus accumulating organisms (PAO) and nitrite oxidizing bacteria (NOB), but they exhibited distinct abundances in WWTPs receiving different categories of wastewater. The denitrifiers in HI-WWTPs was 15.6-32.5% higher than that in other WWTPs, while PAOs had higher abundances in M - and HI-WWTPs (28.9% and 39.3%, respectively) compared with HM-WWTPs. Clear co-occurrence relationships were found among the main functional microbes with similar metabolic characteristics. Moreover, information on functional genes related to carbon, nitrogen and phosphorus metabolism, which is closely associated with pollutant removal efficiency, was obtained. M-WWTPs had higher abundances of genetic expressions for organic matters degradation (i.e. amino acid (10.42%) and carbohydrate (9.86%) metabolisms). Nar, Nir and Nor showed lowest abundances in HM-WWTPs, causing the low nitrogen removal (63.04-65.79%). However, influent type had little effect on genetic expression related with phosphorus removal. This work provided new insights into the interrelationship among bacterial co-occurrence, microbial activity and pollutant removal in WWTPs with different influent types.


Assuntos
Microbiota , Purificação da Água , Nitrogênio , Fósforo , Esgotos , Eliminação de Resíduos Líquidos , Águas Residuárias
9.
Chemosphere ; 281: 130960, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34289620

RESUMO

Powder adsorbents perform well due to their large surface area but are difficult to use because of aggregation and channeling. In this study, pelletization of adsorbents was proposed as a solution to these operating problems. A three-component mixture was extruded into pellets and calcined under air or nitrogen conditions The pellet adsorbent removed 47, 71, 97, and 72% of ammonium, phosphate, sulfathiazole, and sulfamethoxazole, respectively. Bentonite improved greatly the strength of pellets, and a 10 wt% of bentonite was sufficient to maintain pellet shape and mass. No significant difference in individual adsorption and multi-pollutant adsorption was found. Pellet adsorbents with alum sludge, bentonite, and low-grade charcoal are low-cost materials that effectively remove multi-pollutants from the aqueous phase.


Assuntos
Compostos de Amônio , Poluentes Químicos da Água , Adsorção , Compostos de Alúmen , Antibacterianos , Carvão Vegetal , Fosfatos , Esgotos , Sulfonamidas , Poluentes Químicos da Água/análise
10.
Environ Monit Assess ; 193(8): 510, 2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34302207

RESUMO

Prediction models were developed to estimate the extent to which aluminium, chromium, copper, iron, manganese, nickel, lead, and zinc were absorbed in the grains, leaves, stems, and roots of Sorghum bicolor cultivated in soil with various amendment rate of sewage sludge (0, 10, 20, 30, 40, and 50 g/kg) under greenhouse conditions. It was found that, aside from lead, all the examined metals occurred in significantly higher content in the roots compared to aerial tissues. Furthermore, the r-values were significantly negative between the bioconcentration factors of all metals, apart from aluminium and lead, and soil pH, whereas they were significantly positive between the bioconcentration factors, apart from lead, and soil organic matter content (OM). The r-values were typically significantly positive between the levels of all eight metals in the investigated tissues and in the soil. Moreover, the content of all the eight metals in the tissues exhibited a significant negative r-value with soil pH but a significant positive r-value with soil OM. The eight metal contents in the tissues given by the prediction models were quite similar to the real values, suggesting that the created models performed well, as shown by t-tests. It was thus concluded that prediction models were a viable option for evaluating how safe it was to grow S. bicolor in soils with sewage sludge content and at the same time for keeping track of possible human health hazards.


Assuntos
Metais Pesados , Poluentes do Solo , Sorghum , Monitoramento Ambiental , Humanos , Metais Pesados/análise , Esgotos/análise , Solo , Poluentes do Solo/análise
11.
Huan Jing Ke Xue ; 42(8): 3858-3865, 2021 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-34309272

RESUMO

To explore the effects of nitrite generation on the system of short-cut nitrification denitrifying phosphorus removal granules, nitrite was produced continuously and intermittently, under continuous and intermittent aeration, in two groups of SBR reactors of the same size. The effects of nitrogen and phosphorus removal, physical characteristics of the sludge, and microbial community structure were investigated. Nitrite was consumed immediately after intermittent production, with better and more stable nitrogen and phosphorus removal performance. In particular, the average rate of TN removal was 92.07% after 72 days. The utilization efficiency of the carbon source (by P/COD) was concentrated at 0.21-0.22 mg ·mg-1, to ensure full utilization of the carbon source and to further promote denitrification and phosphorus removal. Particle sizes were uniform and showed concentrated distribution, with particles exhibiting regular shapes and clear boundaries. Microbial community analysis showed that the abundance and diversity of microbial communities were higher in the intermittent nitrite system and more enriched in DPAOs genera (Dechloromonas and Pseudomonas). The combination of DPAOs genera and Nitrosomonas resulted in a dynamic balance and stable operation of the short-cut nitrification and denitrifying phosphorus removal system.


Assuntos
Nitrificação , Fósforo , Reatores Biológicos , Desnitrificação , Nitritos , Nitrogênio , Esgotos , Eliminação de Resíduos Líquidos
12.
Huan Jing Ke Xue ; 42(8): 3866-3874, 2021 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-34309273

RESUMO

Ammonia nitrogen (NH4+-N) removal capacities of the A2/O and inverted A2/O processes were analyzed with the same inlet and parallel operation during winter. When the operating water temperature was 14℃, the inverted A2/O process exhibited lower NH4+-N removal from the volumetric load[0.13 kg ·(m3 ·d)-1vs. 0.29 kg ·(m3 ·d)-1] and a lower ammonia oxidation rate (AOR)[0.07 kg ·(kg ·d)-1 vs. 0.11 kg ·(kg ·d)-1] than the A2/O process, whereas the two processes exhibited similar performance at 26℃.The quantitative results for the ammonia oxidizing bacteria (AOB) population were almost the same in the two parallel processes (3.2%±0.24% for the inverted A2/O process and 3.4%±0.31% for the A2/O process). Clone library analysis showed that at low temperatures, the inverted A2/O process had a lower capacity for ammonia nitrogen removal than A2/O process. This is because the particular AOB species[spirillum (Nitrosospira)] facilitated the slower AOR type (K-growth strategy) of nitrosation in the inverted A2/O process, whereas in the A2/O process, the faster AOR type (r-growth strategy) of nitrosation was facilitated by bacterium (Nitrosomonas). At 26℃, the dominant species in the two processes were Nitrosomonas. Through comprehensive analysis of the pollutants during the removal process, we found that although temperature is the leading cause of AOB advantage in species succession, the changes in the inverted A2/O process structure, caused by the aerobic unit, resulted in high COD load and high NH4+-N concentration, which were unfavorable for the growth of AOB. This shows that under conventional sewage conditions, the K-growth strategy is advantageous for the AOB species. Therefore, the structure of the inverted A2/O process for heterotrophic bacteria (phosphorus accumulating bacteria and denitrifying bacteria) indirectly affects the population distribution and succession of autotrophic ammonia-oxidizing bacteria, through COD load and other factors, thereby leading to weakened nitrification capacity at low temperatures.


Assuntos
Amônia , Esgotos , Reatores Biológicos , Desnitrificação , Nitrificação , Nitrogênio , Oxirredução
13.
Huan Jing Ke Xue ; 42(8): 3875-3885, 2021 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-34309274

RESUMO

Bacterial communities are vital for efficient nitrogen removal in an anaerobic ammonium oxidation (ANAMMOX) system. However, the diversity and functional characteristics of a bacterial community during the start-up of ANAMMOX has not been reported. In this study, an up-flow anaerobic sludge bed reactor was used to start-up the ANAMMOX system, and 16S rRNA high-throughput gene sequencing, combined with PICRUSt2-based functional prediction analysis, was used to investigate the dynamic changes in diversity and function of the bacterial community at different times (d0, d30, d60, and d90) during the start-up. The results showed that 48 phyla, 111 classes, 269 orders, 457 families, 840 genera, and 1497 species were present during the start-up of ANAMMOX. Candidatus Brocadia and Candidatus_Kuenenia were the main detected ANAMMOX bacteria, and their relative abundance was significantly different at different times during the start-up of ANAMMOX (P<0.05). During the start-up, the alpha diversity indices of the bacterial community were significantly decreased (P<0.05), and the structure of the bacterial community exhibited significant spatial differentiation (R=0.846, P<0.01). Functional prediction analysis with PICRUSt2 revealed that the bacterial community was active in organic systems and metabolism at hierarchy level 1, implying abundant functional diversity. Further, the abundance of functional genes was significantly different at hierarchy level 2, during the start-up of ANAMMOX. Forty-nine functional genes involving metabolic nitrogen were detected. The abundance of functional genes, involved in nitrification, denitrification, ANAMMOX, and nitrate and nitrite assimilatory/dissimilatory reduction, changed significantly during the start-up of ANAMMOX.


Assuntos
Compostos de Amônio , Desnitrificação , Anaerobiose , Bactérias/genética , Reatores Biológicos , Humanos , Nitrogênio , Oxirredução , RNA Ribossômico 16S , Esgotos
14.
Huan Jing Ke Xue ; 42(8): 3886-3893, 2021 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-34309275

RESUMO

By mining and analyzing the published 16S rRNA amplification data of activated-sludge from 32 sewage and waste-water treatment facilities, at home and abroad, this study examines the microbial structure of sludge and its response to inflow water quality, temperature, and treatment type. Activated sludge generally shows high species diversity and community richness. Many activated sludge samples contain different microbial community structures. In these samples, the dominant bacteria included Thauera, Nitrospira, Comamonas, Dechloromonas, Rhodoferax, Aquihabitans, and Acidovorax. Temperature was negatively correlated with several key denitrifying microorganisms, such as Nitrospira, Aquihabitans, Terrimonas, and Dechloromona. When temperatures were lower than 15℃, the corresponding removal rates of TN and NH4+-N in the 32 sewage treatment plants only reached 49.67% and 63.19%, respectively. With higher BOD5/COD values, these sewage treatment systems exhibited improved biodegradability performances. With higher relative abundances of advantageous functional bacteria, such as Zoogloea, Arcobacter, Acidovorax, and Acinetobacter, pollutant-removal rates would increase accordingly. As for domestic-sewage treatments, the performance of the A2O process is superior to that of the OD, CAS, and CMAS processes. Additionally, the relative abundances of multiple functional dominant bacteria, including Comamonas, Rhodoferax, Nitrospira, and Novosphingobium, were significantly higher in sludge treated with the A2O process than in sludge treated with the other three processes.


Assuntos
Microbiota , Esgotos , Reatores Biológicos , RNA Ribossômico 16S/genética , Eliminação de Resíduos Líquidos , Águas Residuárias
15.
Water Sci Technol ; 84(2): 274-283, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34312335

RESUMO

The paper summarizes the development in the understanding and practical application of the activated sludge process over the last 50 years. Since its invention, the activated sludge process has been a big challenge to design engineers. Traditionally, the technology was covered by sanitary engineers. However, with the development in the understanding of activated sludge process principles, further progress was not possible without knowledge of reaction kinetics and reactor theory. The shift from BOD removal only to combined removal of organic pollution, nitrogen and phosphorus required a chemical engineering approach with outputs of activated sludge microbiology and microbial ecology. Molecular biology enabled more accurate identification of important activated sludge microorganisms. The development in activated sludge process also required more efficient activated sludge separation and thickening. The paper describes the development from secondary clarifiers to membrane separation. Increasing water stress around the globe has also changed the main wastewater paradigm from wastewater treatment and safe discharge to safe reuse.


Assuntos
Eliminação de Resíduos Líquidos , Purificação da Água , Reatores Biológicos , Nitrogênio , Fósforo , Esgotos , Águas Residuárias
16.
Water Sci Technol ; 84(2): 284-292, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34312336

RESUMO

The uncertainty associated with the determination of load parameters, which is a key step in the design of wastewater treatment plants (WWTPs), was investigated on the basis of data sets from 58 WWTPs. A further analysed aspect was the organic load variations associated with variable sewage temperatures. Data from 26 WWTPs with a high inflow sampling frequency was used to simulate scenarios to investigate the effect of lower sampling frequencies through a Monte Carlo approach. The calculation of 85-percentile values for chemical oxygen demand (COD) loadings based on only 26 samples per year is associated with a variability of up to ±18%. Approximately 90 samples per year will be necessary to reduce this uncertainty for estimation of COD loadings below 10%. Hence, a low sampling frequency can potentially lead to under- or overestimation of design parameters. Through an analogous approach, it was possible to identify uncertainties of ±11% in COD loading when weekly average data was used with four samples per week. Finally, a tendency to lower COD input loads with increasing temperatures was identified, with a reduction of about 1% of the average loading per degree Celsius.


Assuntos
Esgotos , Purificação da Água , Análise da Demanda Biológica de Oxigênio , Eliminação de Resíduos Líquidos , Águas Residuárias/análise
17.
Water Sci Technol ; 84(2): 293-301, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34312337

RESUMO

This paper describes the commissioning of the new water line (NWL) of the Central wastewater treatment plant in Prague and also the gradual reduction of the existing water line (EWL) loading. Concerning the NWL, the gradual start-up of the process without inoculation will be described. As to the EWL, the presentation describes the adaptation of the EWL operation to the relatively quick reduction of loading to approximately 35%.


Assuntos
Eliminação de Resíduos Líquidos , Purificação da Água , Esgotos , Águas Residuárias , Água
18.
Water Sci Technol ; 84(2): 302-313, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34312338

RESUMO

Most cold-climate biological nutrient removal facilities experience poor settling mixed liquor during winter, resulting in treatment capacity throughput limitations. The Metro Wastewater Reclamation District in Denver, Colorado, operated two full-scale secondary treatment trains to compare the existing biological nutrient removal configuration (Control) to one that was modified to operate with an anaerobic selector and with hydrocyclone selective wasting (Test) to induce granulation. Results from this evaluation showed that the Test achieved significantly better settling behaviour than the Control. The difference in the mean diluted SVI30 between the Test and Control were statistically significant (P < 0.05), with values of 77 ± 17 and 135 ± 25 mL/g observed for the Test and Control respectively. These settling results were accompanied by differences in the particle size distribution, with notably higher settling velocities commensurate with increasing particle size. The degree of granulation observed in the Test train was between 32 and 56% of the mass greater than ≥250 µm in particle size whereas 16% of the mixed liquor in the Control was ≥250 µm over the entire study period. The improved settling behaviour of the Test configuration may translate into an increase of secondary treatment capacity during winter by 32%.


Assuntos
Esgotos , Eliminação de Resíduos Líquidos , Reatores Biológicos , Tamanho da Partícula , Águas Residuárias
19.
Water Sci Technol ; 84(2): 314-322, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34312339

RESUMO

Operational data over 2 years from three large Austrian wastewater treatment plants (WWTPs) with design capacities of 4 million, 950,000 and 110,000 population equivalent (PE) were examined. Salt peaks, due to thawing road salt were detected and quantified by electrical conductivity, temperature and chloride measurement in the inflow of the WWTPs. Daily NaCl inflow loads up to 1,147 t/d and PE-specific loads of 0.26-0.5 kg NaCl/(PE · y) were found. To mimic the plants' behaviour in a controlled environment, NaCl was dosed into the inflow of a laboratory-scale activated sludge plant. The influence of salt peaks on important activated sludge parameters such as sludge volume index, settling velocity and floc size were investigated. Influent and effluent were sampled extensively to calculate removal rates. Respiration measurements were performed to quantify activated sludge activity. Particle size distributions of the activated sludge floc sizes were measured using laser diffraction particle sizing and showed a decrease of the floc size by approximately two-thirds. The floc structure was examined and documented using light microscopy. At salt concentrations below 1 g/L, increased respiration was found for autotrophic biomass, and between 1 and 3 g NaCl/L respiration was inhibited by up to 30%.


Assuntos
Esgotos , Purificação da Água , Áustria , Floculação , Cloreto de Sódio , Eliminação de Resíduos Líquidos , Águas Residuárias
20.
Water Sci Technol ; 84(2): 323-332, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34312340

RESUMO

Hydrodynamic simulation (CFD: computational fluid dynamics) is one of the major tools for planning the reconstruction and operation of the structures in wastewater treatment plants, and its routine use is commonplace because of the cost savings and efficiency gains that can be achieved. This paper provides examples of how CFD can contribute to substantial improvements in the overall efficiency of wastewater treatment plants.The case studies presented in the paper include rarely investigated issues, such as the operation of aerated grit chambers, performance of primary settling tanks, mixing performance in oxidation ditches and return sludge control. The results show that: (1) air intake rate can be strongly decreased in most of the grit chambers, (2) optimization of the inlet geometry design of primary settling tanks is crucial, especially at high loads caused by storm events, (3) mixer performance design based on current design guidelines is often of an unnecessarily high capacity, (4) sludge recirculation rate should be optimized by CFD investigations based on secondary settling tank performance.


Assuntos
Eliminação de Resíduos Líquidos , Purificação da Água , Hidrodinâmica , Modelos Teóricos , Esgotos
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