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Letters in Applied Microbiology Feb 2022Bacterial species capable of performing both nitrification and denitrification in a single vessel under similar conditions have gained significance in the wastewater... (Review)
Review
Role of heterotrophic nitrifiers and aerobic denitrifiers in simultaneous nitrification and denitrification process: a nonconventional nitrogen removal pathway in wastewater treatment.
Bacterial species capable of performing both nitrification and denitrification in a single vessel under similar conditions have gained significance in the wastewater treatment scenario considering their unique character of performing the above reactions under heterotrophic and aerobic conditions respectively. Such a novel strategy often referred to as simultaneous nitrification and denitrification (SND) has a tremendous potential in dealing with various wastewaters having low C : N content, considering that the process needs very little or no external carbon source and oxygen supply thus adding to its cost-effective and environmentally friendly nature. Though like other micro-organisms, heterotrophic nitrifiers and aerobic denitrifiers convert inorganic or organic nitrogen-containing substances into harmless dinitrogen gas in the wastewater, their ecophysiological role in the global nitrogen cycle is still not fully understood. Attempts to highlight the role played by the heterotrophic nitrifiers and aerobic denitrifiers in dealing with nitrogen pollution under various environmental operating conditions will help in developing a mechanistic understanding of the SND process to address the issues faced by the traditional methods of aerobic autotrophic nitrification-anaerobic heterotrophic denitrification.
Topics: Aerobiosis; Denitrification; Nitrification; Nitrogen; Wastewater; Water Purification
PubMed: 34402087
DOI: 10.1111/lam.13553 -
Bioresource Technology Jun 2016Aerobic granules are large biological aggregates with compact interiors that can be used in efficient wastewater treatment. This mini-review presents new researches on... (Review)
Review
Aerobic granules are large biological aggregates with compact interiors that can be used in efficient wastewater treatment. This mini-review presents new researches on the development of aerobic granular processes, extended treatments for complicated pollutants, granulation mechanisms and enhancements of granule stability in long-term operation or storage, and the reuse of waste biomass as renewable resources. A discussion on the challenges of, and prospects for, the commercialization of aerobic granular process is provided.
Topics: Aerobiosis; Bioreactors; Research; Sewage; Wastewater; Water Purification
PubMed: 26873285
DOI: 10.1016/j.biortech.2016.01.098 -
Journal of Applied Microbiology Jan 2022This study evaluated pH reduction and microbial growth during fermentation of maize stover (MS) mixed with banana pseudostem (BPS) under South Ethiopian conditions.
AIMS
This study evaluated pH reduction and microbial growth during fermentation of maize stover (MS) mixed with banana pseudostem (BPS) under South Ethiopian conditions.
MATERIALS AND RESULTS
The MS and BPS were chopped and mixed into six treatments (T): 80% BPS plus 20% DMS (T1), 70% BPS plus 30% DMS (T2), 40% BPS plus 60% FMS (fresh MS) (T3), 20% BPS plus 80% FMS (T4), 100% FMS (T5), and 95% BPS plus 5% molasses (T6). At 0, 7, 14, 30, 60, and 90 days, pH and dry matter were determined. Microbiological quality was assessed using plate counts and Illumina MiSeq sequencing. On day 60 and 90, aerobic stability was investigated. The results showed a significant reduction in pH in all mixtures, except in T1 and T2. Lactic acid bacteria counts reached a maximum in all treatments within 14 days. Sequencing showed marked changes in dominant bacteria, such as Buttiauxella and Acinetobacter to Lactobacillus and Bifidobacterium.
CONCLUSIONS
The fresh MS and BPS mixtures and fresh maize showed significant pH reduction and dominance of desirable microbial groups.
SIGNIFICANCE AND IMPACT OF THE STUDY
The study enables year-round livestock feed supplementation to boost milk and meat production in South Ethiopia.
Topics: Aerobiosis; Ethiopia; Fermentation; Musa; Silage; Zea mays
PubMed: 34133817
DOI: 10.1111/jam.15183 -
Bioresource Technology Nov 2021Yeast strain K1, isolated from surface sediment, was identified as Barnettozyma californica. The strain showed efficient heterotrophic nitrification and aerobic...
Yeast strain K1, isolated from surface sediment, was identified as Barnettozyma californica. The strain showed efficient heterotrophic nitrification and aerobic denitrification (HN-AD) at initial ammonium, nitrite and nitrate concentrations of 14-140 mg/L. Additionally, the optimum carbon source for its growth and nitrogen removal activity was sucrose, followed by glucose, acetate and citrate. The maximum removal efficiencies of ammonium, nitrite and nitrate were 99.11%, 99.13% and 98.84% under 48 h of culture with sucrose at 140 mg/L nitrogen and the corresponding removal efficiencies of total nitrogen were 90.16%, 86.65% and 81.48%, respectively. The optimum conditions for the inorganic nitrogen removal and growth of strain K1 were a C/N of 18 and a salinity of 5-15 ppt. The amoA, nirK and nosZ genes of K1 were detected. All the results suggest that B. californica K1 is capable of HN-AD and has the potential to remove inorganic nitrogen from wastewater.
Topics: Aerobiosis; Ammonium Compounds; Denitrification; Heterotrophic Processes; Nitrification; Nitrites; Nitrogen; Saccharomyces cerevisiae; Saccharomycetales
PubMed: 34332179
DOI: 10.1016/j.biortech.2021.125665 -
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 -
Anaerobe Apr 2017The microbiota of the gut has many crucial functions in human health. Dysbiosis of the microbiota has been correlated to a large and still increasing number of diseases.... (Review)
Review
The microbiota of the gut has many crucial functions in human health. Dysbiosis of the microbiota has been correlated to a large and still increasing number of diseases. Recent studies have mostly focused on analyzing the associations between disease and an aberrant microbiota composition. Functional studies using (in vitro) gut models are required to investigate the precise interactions that occur between specific bacteria (or bacterial mixtures) and gut epithelial cells. As most gut bacteria are obligate or facultative anaerobes, studying their effect on oxygen-requiring human gut epithelial cells is technically challenging. Still, several (anaerobic) bacterial-epithelial co-culture systems have recently been developed that mimic host-microbe interactions occurring in the human gut, including 1) the Transwell "apical anaerobic model of the intestinal epithelial barrier", 2) the Host-Microbiota Interaction (HMI) module, 3) the "Human oxygen-Bacteria anaerobic" (HoxBan) system, 4) the human gut-on-a-chip and 5) the HuMiX model. This review discusses the role of gut microbiota in health and disease and gives an overview of the characteristics and applications of these novel host-microbe co-culture systems.
Topics: Aerobiosis; Anaerobiosis; Coculture Techniques; Gastrointestinal Tract; Host-Pathogen Interactions; Humans; Models, Biological
PubMed: 28062270
DOI: 10.1016/j.anaerobe.2017.01.001 -
Water Research Feb 2020The increasing use of perfluorooctanoic acid (PFOA) raises concerns about its potential toxicity to the environment. However, the interaction between PFOA and aerobic...
The increasing use of perfluorooctanoic acid (PFOA) raises concerns about its potential toxicity to the environment. However, the interaction between PFOA and aerobic granular sludge has never been documented. This work therefore aims to provide such support through investigating the fate of PFOA at environmentally relevant levels in aerobic granular sludge systems and its impact on aerobic granular sludge. Experimental results showed that 32.0%∼36.4% of wastewater PFOA was removed by aerobic granular sludge in stable operation when PFOA concentration was ranged from 0.1 to 1.0 mg/L. Mass balance analyses and X-ray photoelectron spectroscopy survey scan revealed that the removal of PFOA was dominated by adsorption rather than biodegradation, and sorption kinetic analysis indicated that inhomogeneous multilayer adsorption was responsible for this removal. The adsorbed PFOA deteriorated the settleability of granular sludge and biological nitrogen and phosphorus removal significantly. Experimental results showed that 1.0 mg/L PFOA inhibited anaerobic phosphate release, aerobic phosphate uptake, nitrate reduction, and nitrite reduction processes by 60%, 50%, 13.1%, and 5.8%, respectively. It was observed that PFOA induced large amounts of filamentous villus growing on the surface and increased the extracellular polymeric substances of granular sludge. Fourier-transform infrared spectra and X-ray photoelectron spectroscopy spectrum showed that several function groups in extracellular polymeric substances such as hydroxyl groups, amides and polysaccharides were affected by PFOA. It was also found that PFOA inhibited the cyclic transformations of polyhydroxyalkanoates and glycogen. Microbial community analyses showed that PFOA decreased the abundances of Nitrosomonas, Nitrospira, Accumulibacter, and other function microbes such as Rhodospirillaceae, Thauera, and Azoarcus.
Topics: Aerobiosis; Bioreactors; Caprylates; Fluorocarbons; Kinetics; Nitrogen; Sewage; Waste Disposal, Fluid
PubMed: 31706128
DOI: 10.1016/j.watres.2019.115249 -
The Science of the Total Environment Aug 2020Aerobic denitrification is a novel biological nitrogen removal technology, which has been widely investigated as an alternative to the conventional denitrification and... (Review)
Review
Aerobic denitrification is a novel biological nitrogen removal technology, which has been widely investigated as an alternative to the conventional denitrification and for its unique advantages. To fully comprehend aerobic denitrification, it is essential to clarify the regulatory mechanisms of intracellular electron transfer during aerobic denitrification. However, reports on intracellular electron transfer during aerobic denitrification are rather limited. Thus, the purpose of this review is to discuss the molecular mechanism of aerobic denitrification from the perspective of electron transfer, by summarizing the advancements in current research on electron transfer based on conventional denitrification. Firstly, the implication of aerobic denitrification is briefly discussed, and the status of current research on aerobic denitrification is summarized. Then, the occurring foundation and significance of aerobic denitrification are discussed based on a brief review of the key components involved in the electron transfer of denitrifying enzymes. Moreover, a strategy for enhancing the efficiency of aerobic denitrification is proposed on the basis of the regulatory mechanisms of denitrification enzymes. Finally, scientific outlooks are given for further investigation on aerobic denitrification in the future. This review could help clarify the mechanism of aerobic denitrification from the perspective of electron transfer.
Topics: Aerobiosis; Denitrification; Electron Transport; Electrons; Nitrates; Nitrogen
PubMed: 32417477
DOI: 10.1016/j.scitotenv.2020.139080 -
Water Science and Technology : a... Nov 2021Currently, research trends on aerobic granular sludge (AGS) have integrated the operating conditions of extracellular polymeric substances (EPS) towards the stability of... (Review)
Review
Currently, research trends on aerobic granular sludge (AGS) have integrated the operating conditions of extracellular polymeric substances (EPS) towards the stability of AGS systems in various types of wastewater with different physical and biochemical characteristics. More attention is given to the stability of the AGS system for real site applications. Although recent studies have reported comprehensively the mechanism of AGS formation and stability in relation to other intermolecular interactions such as microbial distribution, shock loading and toxicity, standard operating condition control strategies for different types of wastewater have not yet been discussed. Thus, the dimensional multi-layer structural model of AGS is discussed comprehensively in the first part of this review paper, focusing on diameter size, thickness variability of each layer and diffusion factor. This can assist in facilitating the interrelation between disposition and stability of AGS structure to correspond to the changes in wastewater types, which is the main objective and novelty of this review.
Topics: Aerobiosis; Bioreactors; Sewage; Waste Disposal, Fluid; Wastewater
PubMed: 34810301
DOI: 10.2166/wst.2021.415 -
Water Science and Technology : a... May 2023The formation and evolution of aerobic granular sludge (AGS) developed in a sequential batch reactor (SBR) were evaluated to understand the effect of influential...
The formation and evolution of aerobic granular sludge (AGS) developed in a sequential batch reactor (SBR) were evaluated to understand the effect of influential operating parameters on its morphology, stability, and removal performance while treating industrial/municipal wastewater. After 18 days of operation (stage I), mature granules were identified in the reactor, and in 25 days, the AGS system reached a stable operation. The chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN) were affected by the applied operating variations (from stages II to VII). Until day 48 (stage III), the aerobic granules did not show relevant changes in shape and stability. During this stage, the AGS system achieved high removal efficiencies of COD (97.7%) and TKN (86.2%) and a sludge volume index (SVI) of 65 ± 6.7 mL/g-total suspended solids. From stage IV until the end of the reactor operation, partial disintegration and rupture occurred in the system, but granules did not completely disintegrate. Specifically, a volumetric exchange ratio (VER) of >67% and an aeration rate (AR) of <2.5 L/min promoted the compactness and the structural integrity of AGS. The principal component analysis corroborated that the rise in the VER is an effective strategy for improving AGS stability and organic pollutant removal.
Topics: Sewage; Waste Disposal, Fluid; Bioreactors; Wastewater; Aerobiosis; Nitrogen; Water Purification
PubMed: 37186634
DOI: 10.2166/wst.2023.121