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Molecules (Basel, Switzerland) Nov 2021Lactate and isoprene are two common monomers for the industrial production of polyesters and synthetic rubbers. The present study tested the co-production of D-lactate...
Lactate and isoprene are two common monomers for the industrial production of polyesters and synthetic rubbers. The present study tested the co-production of D-lactate and isoprene by engineered in microaerobic conditions. The deletion of alcohol dehydrogenase () and acetate kinase () genes, along with the supplementation with betaine, improved the co-production of lactate and isoprene from the substrates of glucose and mevalonate. In fed-batch studies, microaerobic fermentation significantly improved the isoprene concentration in fermentation outlet gas (average 0.021 g/L), compared with fermentation under aerobic conditions (average 0.0009 g/L). The final production of D-lactate and isoprene can reach 44.0 g/L and 3.2 g/L, respectively, through fed-batch microaerobic fermentation. Our study demonstrated a dual-phase production strategy in the co-production of isoprene (gas phase) and lactate (liquid phase). The increased concentration of gas-phase isoprene could benefit the downstream process and decrease the production cost to collect and purify the bio-isoprene from the fermentation outlet gas. The proposed microaerobic process can potentially be applied in the production of other volatile bioproducts to benefit the downstream purification process.
Topics: Aerobiosis; Butadienes; Escherichia coli; Fermentation; Hemiterpenes; Lactic Acid; Metabolic Engineering; Mevalonic Acid
PubMed: 34885764
DOI: 10.3390/molecules26237173 -
Journal of Applied Microbiology Feb 2022Our purpose was to clarify the effect of sulfamethoxazole (SMX) on the start-up period, particle formation, and treatment efficiency of an aerobic granular sludge system.
AIMS
Our purpose was to clarify the effect of sulfamethoxazole (SMX) on the start-up period, particle formation, and treatment efficiency of an aerobic granular sludge system.
METHODS AND RESULTS
We compared an R1 granular sequencing batch reactor (GSBR) started with 5 μg L SMX and an R2 GSBR started without SMX, as a control, to investigate the impact of a trace amount of SMX (5 μg L ) on aerobic granular sludge (AGS) characteristics and the removal of conventional contaminants. AGS granulation in the R1 system was not inhibited by SMX, but the granule particle size was smaller than that in the R2 system. Both systems had good performance removing conventional pollutants. Extracellular polymeric substance secretion in the R1 system was lower than that in the R2 system. After stabilizing reactor operations, the SMX removal efficiency in the R1 system (~73.93%) was higher than that in the R2 system (~70.66%). The start-up modes also determined the differences in the microbial community structure of the AGS systems.
CONCLUSIONS
SMX-activated AGS performed better than AGS without SMX.
SIGNIFICANCE AND IMPACT OF STUDY
The study can help engineers determine start-up modes with varieties of antibiotics in AGS processes and provide references for the optimization of water treatment processes.
Topics: Aerobiosis; Bioreactors; Extracellular Polymeric Substance Matrix; Sewage; Sulfamethoxazole; Waste Disposal, Fluid
PubMed: 34453874
DOI: 10.1111/jam.15267 -
Huan Jing Ke Xue= Huanjing Kexue Oct 2020Long-term stability is important for the practical application of aerobic granular sludge system under low carbon to nitrogen ratio (C/N). In this study, aerobic...
Long-term stability is important for the practical application of aerobic granular sludge system under low carbon to nitrogen ratio (C/N). In this study, aerobic granular sludge, seeded in the reactors A and B, were cultivated under low C/N to investigate the properties, performance, and resilience to shock load in the long-term operation. The load of carbon and nitrogen in the feed was increased gradually. The C/N of reactor A was kept at 2, while that of reactor B was kept at 4 initially and then reduced to 2 in the shock load stage. It was discovered that the aerobic granular sludge stored at 4℃ for 30 days was essentially revived after 25 days of cultivation in reactors A and B, with over 90% removal efficiency for COD and ammonia, respectively. In the following stages, the removal efficiencies of COD and ammonia in reactor B were over 90% and complete nitrification was achieved. In contrast, in reactor A, the removal efficiency of COD was only 80% and only partial nitrification was achieved; however, ammonia removal efficiency of 90% was finally achieved. In the shock load stage, the COD removal efficiencies in reactors A and B were still above 80%, but the ammonia removal efficiencies were severely affected. The removal of ammonia was deteriorated in reactor A, while only partial nitrification was achieved in reactor B. During the entire operation, the physical properties of the aerobic granules in reactors A and B were barely affected, with sludge volume index (SVI) in reactors A and B maintained at 60 mL ·g and 75 mL ·g, and mixed liquid suspended solid (MLSS) at 5 g ·Land 3.7 g ·L, respectively. Microbial analysis showed that the aerobic granular sludge in reactor B has richer and more diverse microbial community than that in reactor A. The abundance of in reactor B, which is simultaneously able to produce polymeric protein and stabilize the structure of the aerobic granules, may be favorable for the high stability of the aerobic granules. These findings suggested that the aerobic granular system under the C/N of 4 had better performance in ammonia removal and higher tolerance to shock load, which guaranteed high stability of the aerobic granular sludge system in long-term operation, as compared to that under the C/N of 2.
Topics: Aerobiosis; Bioreactors; Carbon; Nitrogen; Sewage; Waste Disposal, Fluid
PubMed: 33124399
DOI: 10.13227/j.hjkx.202001209 -
Biotechnology Advances 2018In the wake of the success of aerobic granulation in sequential batch reactors (SBRs) for treating wastewater, attention is beginning to turn to continuous flow... (Review)
Review
In the wake of the success of aerobic granulation in sequential batch reactors (SBRs) for treating wastewater, attention is beginning to turn to continuous flow applications. This is a necessary step given the advantages of continuous flow treatment processes and the fact that the majority of full-scale wastewater treatment plants across the world are operated with aeration tanks and clarifiers in a continuous flow mode. As in SBRs, applying a selection pressure, based on differences in either settling velocity or the size of the biomass, is essential for successful granulation in continuous flow reactors (CFRs). CFRs employed for aerobic granulation come in multiple configurations, each with their own means of achieving such a selection pressure. Other factors, such as bioaugmentation and hydraulic shear force, also contribute to aerobic granulation to some extent. Besides the formation of aerobic granules, long-term stability of aerobic granules is also a critical issue to be addressed. Inorganic precipitation, special inocula, and various operational optimization strategies have been used to improve granule long-term structural integrity. Accumulated studies reviewed in this work demonstrate that aerobic granulation in CFRs is capable of removing a wide spectrum of contaminants and achieving properties generally comparable to those in SBRs. Despite the notable research progress made toward successful aerobic granulation in lab-scale CFRs, to the best of our knowledge, there are only three full-scale tests of the technique, two being seeded with anammox-supported aerobic granules and the other with conventional aerobic granules; two other process alternatives are currently in development. Application of settling- or size-based selection pressures and feast/famine conditions are especially difficult to implement to these and similar mainstream systems. Future research efforts needs to be focused on the optimization of the granule-to-floc ratio, enhancement of granule activity, improvement of long-term granule stability, and a better understanding of aerobic granulation mechanisms in CFRs, especially in full-scale applications.
Topics: Aerobiosis; Bioreactors; Membranes, Artificial; Sewage; Water Purification
PubMed: 29597030
DOI: 10.1016/j.biotechadv.2018.03.015 -
Journal of Hazardous Materials Jan 2022Aerobic granular sludge potential for concurrent biodegradation of two nitrogenous heterocyclic compounds (NHCs), i.e., pyridine and indole, and ammonia nitrogen along...
Aerobic granular sludge potential for concurrent biodegradation of two nitrogenous heterocyclic compounds (NHCs), i.e., pyridine and indole, and ammonia nitrogen along with phenol and thiocyanate was investigated in three sequencing batch reactors (SBRs) (R1, R2, and R3). Pyridine and indole were provided, respectively, in R1 and R2, whereas R3 was operated with a mixture of equimolar concentrations of pyridine and indole. Three concentrations of NHCs (1.0, 2.5, and 5.0 mM) were investigated to observe the impact on aerobic granules. Pyridine did not exhibit any adverse effect on the granular characteristics (volatile suspended solids of 6.00 ± 0.08 g L and sludge volume index of 37.98 ± 0.84 mL gTSS) up to a concentration of 5.0 mM (402.93 ± 6.29 mg L) (R1) with around 74% and >98% removal for pyridine and other pollutants (phenol, thiocyanate, and ammonia nitrogen), respectively. However, indole had a substantial adverse impact on the granular characteristics and other contaminants removal with a concentration of more than 1.0 mM (120.65 ± 4.84 mg L) (R2). The current research work provides an experimental treatment methodology for the wastewater in which pyridine, indole, ammonium, phenol, and thiocyanate coexist.
Topics: Aerobiosis; Ammonium Compounds; Bioreactors; Indoles; Nitrogen; Phenol; Phenols; Pyridines; Sewage; Thiocyanates; Waste Disposal, Fluid
PubMed: 34403942
DOI: 10.1016/j.jhazmat.2021.126861 -
Methods in Molecular Biology (Clifton,... 2017Currently, there is no universally accepted standard media or method for the recovery of Campylobacter species. This is likely due to the ubiquity of the organism in...
Currently, there is no universally accepted standard media or method for the recovery of Campylobacter species. This is likely due to the ubiquity of the organism in nature, the complex sample matrices from which the organism is often recovered, as well as the fragile/viable-but nonculturable state the organism assumes in response to stress. The use of a sterile filter placed upon a nonselective Brucella Agar Blood Plate (BAB), followed by incubation at 37 °C in a hydrogen-containing atmosphere (Campycheck), is one method to recover stressed and emerging Campylobacter spp. from complex environmental matrices; however, this technique does not currently allow for the enumeration of the recovered organisms. Enumeration is performed using serial dilutions of sample homogenate plated onto modified Campy-Cefex media followed by incubation at either 37 °C or 42 °C in a microaerobic atmosphere.
Topics: Aerobiosis; Agar; Animals; Campylobacter jejuni; Colony Count, Microbial; Culture Media; Feces; Humans; Soil Microbiology; Water Microbiology
PubMed: 27885593
DOI: 10.1007/978-1-4939-6536-6_1 -
Bioresource Technology Mar 2022The utilization of actinomycetes as the bioresources for heterotrophic nitrification and aerobic denitrification is rarely reported due to the lack of work to explore...
The utilization of actinomycetes as the bioresources for heterotrophic nitrification and aerobic denitrification is rarely reported due to the lack of work to explore their nitrogen biodegradation capabilities. Streptomyces mediolani EM-B2 belonging to actinomycetes could effectively remove high concentration of multiple nitrogen forms, and the maximum removal rates of ammonium, nitrate and nitrite reached 3.46 mg/(L·h), 1.71 mg/(L·h) and 1.73 mg/(L·h), respectively. Nitrite was preferentially consumed from the simultaneous nitrification and denitrification reaction system. Nitrogen balance analysis uncovered that more than 37% of the initial total nitrogen was converted to nitrogenous gas by aerobic denitrification. Experiments with specific inhibitors of nitrification and denitrification revealed that strain EM-B2 contained ammonia monooxygenase, hydroxylamine oxidoreductase, nitrate reductase and nitrite oxidoreductase, which were successfully expressed and detected as 0.43, 0.59, 0.12 and 0.005 U/mg proteins, respectively. These findings may provide new insights into the actinomycetes for bioremediation of nitrogen pollution wastewater.
Topics: Aerobiosis; Ammonium Compounds; Denitrification; Heterotrophic Processes; Nitrification; Nitrites; Nitrogen; Streptomyces
PubMed: 35134523
DOI: 10.1016/j.biortech.2022.126819 -
Journal of Environmental Management Oct 2020Aerobic granular sludge (AGS) is a type of biofilm with good sedimentation and density, high biomass, high organic load tolerance and toxicity resistance....
Aerobic granular sludge (AGS) is a type of biofilm with good sedimentation and density, high biomass, high organic load tolerance and toxicity resistance. Oxytetracycline (OTC) is an antibiotic widely used in livestock and aquaculture, and its low absorption and high residue bring many risks and harms to the ecological environment. In this study, an OTC-degrading strain TJ3 was isolated from AGS and identified as Pandoraea sp. The biodegradation characteristics of OTC by strain TJ3 under different environmental conditions were also investigated. The results showed that the optimal initial pH value and temperature for the culture strain were 6.0 and 30 °C, respectively. At an inoculation dose of 6% (v/v), the removal rate of OTC by strain TJ3 was remarkable (59.4%). Furthermore, when the sodium acetate was present as an additional substrate, the biomass and the OTC removal rate of strain TJ3 were improved. The biodegradability of strain TJ3 to OTC was proved by LC-QTOF/MS, and two possible biotransformation products, i.e. m/z 416 and 219, were identified. In the bioaugmentation experiments of AGS by strain TJ3, the average OTC removal rate was 92.89% after the stable operation of bioreactor. The chemical oxygen demand (COD), ammonium nitrogen (NH-N) and total phosphorus (TP) were efficiently removed. The microbial community structure had significantly changed at the genus level, and the relative abundance of Zoogloea, Pandoraea, Cloacibacterium and Desulfovibrio increased evidently. These results implied that the OTC removal performance and the structural stability of AGS were improved. In this study, Pandoraea sp. TJ3 was applied to removal OTC for the first time, and results showed that Pandoraea sp. TJ3 may be a new auxiliary bacterial resource for the biodegradation of OTC and a potential candidate in the treatment of antibiotic wastewater.
Topics: Aerobiosis; Bacteria; Biological Oxygen Demand Analysis; Bioreactors; Nitrogen; Oxytetracycline; Sewage; Waste Disposal, Fluid
PubMed: 32738758
DOI: 10.1016/j.jenvman.2020.111115 -
Environmental Monitoring and Assessment Feb 2023This paper presents an assessment of the start-up performance of aerobic granular sludge (AGS) for the treatment of low-strength (chemical oxygen demand,...
This paper presents an assessment of the start-up performance of aerobic granular sludge (AGS) for the treatment of low-strength (chemical oxygen demand, COD < 200 mg/L) domestic wastewater by the application of a diatomite carrier. The feasibility was evaluated in terms of the start-up period and stability of the aerobic granules as well as COD and phosphate removal efficiencies. A single pilot-scale sequencing batch reactor (SBR) was used and operated separately for the control granulation and granulation with diatomite. Complete granulation (granulation rate ≥ 90%) was achieved within 20 days for the case of diatomite with an average influent COD concentration of 184 mg/L. In comparison, control granulation required 85 days to accomplish the same feat with a higher average influent COD concentration (253 mg/L). The presence of diatomite solidifies the core of the granules and enhances physical stability. AGS with diatomite recorded the strength and sludge volume index of 18 IC and 53 mL/g suspended solids (SS) which is superior to control AGS without diatomite (19.3 IC, 81 mL/g SS). Quick start-up and achievement of stable granules lead to an efficient COD (89%) and phosphate removal (74%) in 50 days of bioreactor operation. Interestingly, this study revealed that diatomite has some special mechanism in enhancing the removal of both COD and phosphate. Also, diatomite has a significant influence on microbial diversity. The result of this research implies that the advanced development of granular sludge by using diatomite can provide promising low-strength wastewater treatment.
Topics: Sewage; Waste Disposal, Fluid; Aerobiosis; Environmental Monitoring; Phosphates; Water Purification; Bioreactors; Nitrogen
PubMed: 36809517
DOI: 10.1007/s10661-023-11028-9 -
International Journal of Environmental... Nov 2022Aerobic granular sludge (AGS) is a promising technology for wastewater treatment. AGS formation belongs to microbial self-aggregation. Investigation of the formation and...
Aerobic granular sludge (AGS) is a promising technology for wastewater treatment. AGS formation belongs to microbial self-aggregation. Investigation of the formation and stability of AGS is widely paid attention to, in particular the structure stability of large size granules. Two types of AGS were developed in two sequencing batch reactors fed by two different wastewaters, respectively. Through confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM), the structure and composition of granules were analyzed. Filamentous bacteria were observed in granules from synthetic wastewater reactor, while filamentous bacteria and stalked ciliates ( sp.) were simultaneously found in granules from domestic wastewater reactor. The analytic results show that filamentous bacteria and stalked ciliates acting as skeletons play important roles in the formation and stability of granules. With the bonding of extracellular polymeric substances (EPS), the filamentous bacteria and stalked ciliates could build bridges and frames to promote the aggregation of bacteria; these microorganisms could create a space grid structure around the surface layer of granules to enhance the strength of granules, and the remnants of the stalks could serve as supports to fix the steadiness of granules.
Topics: Sewage; Wastewater; Waste Disposal, Fluid; Bioreactors; Aerobiosis; Bacteria
PubMed: 36497821
DOI: 10.3390/ijerph192315747