-
Bioresource Technology May 2010Introduction, consolidation and even standardization of expensive conventional aerobic systems for domestic wastewater treatment imposed significant financial... (Review)
Review
Introduction, consolidation and even standardization of expensive conventional aerobic systems for domestic wastewater treatment imposed significant financial constraints on the expansion of sanitary services including treatment in developing countries. A viable alternative is the sequential anaerobic-aerobic systems. If compared with the conventional aerobic technologies based on activated sludge processes, lower energy consumption and lower excess sludge production can be achieved with a high-rate anaerobic pre-treatment step. Particularly with concentrated sewage, the energy benefit of applying anaerobic pre-treatment will become very significant. This study aims on putting the effectiveness of sequential systems for treatment of domestic wastewater on view, through displaying results presented in literature on the performance of these systems.
Topics: Aerobiosis; Anaerobiosis; Sanitary Engineering; Sewage; Water
PubMed: 20079630
DOI: 10.1016/j.biortech.2009.12.039 -
International Journal of Environmental... Jul 2022Improving treatment efficiency and reducing investment and operating costs make aerobic granular sludge technology (AGS) a promising technology for treating aquaculture...
Improving treatment efficiency and reducing investment and operating costs make aerobic granular sludge technology (AGS) a promising technology for treating aquaculture wastewater. The development of continuous flow reactors (CFRs) has become a new direction in the research of AGS. This study clarifies the granulation effect, hydrodynamic behavior and particle separation of three different CFRs (R1 to R3). The established CFD model was able to explain the hydrodynamic behavior in all three CFRs; in particular, R3 performed the best from the perspective of hydrodynamic behavior due to its abundant turbulence. In addition, the optimal baffle distance and baffle angle of R3 were simulated to be 40 mm and 60°, respectively, due to them providing the best turbulent flow and particle separation effect. However, an overlarge baffle angle could weaken the turbulent pattern in the reactor. The retention time distribution further confirmed the reasonability of these optimal parameters with the highest effective volume ratio of 0.82. In short, this study gives an instruction for exploring the rapid formation mechanism of AGS in a CFR to promote its engineering application.
Topics: Aerobiosis; Bioreactors; Hydrodynamics; Sewage; Waste Disposal, Fluid
PubMed: 35886165
DOI: 10.3390/ijerph19148306 -
G3 (Bethesda, Md.) Dec 2018Next generation biofuels including longer-chain alcohols such as butanol are attractive as renewable, high-energy fuels. A barrier to microbial production of butanols is...
Next generation biofuels including longer-chain alcohols such as butanol are attractive as renewable, high-energy fuels. A barrier to microbial production of butanols is the increased toxicity compared to ethanol; however, the cellular targets and microbial defense mechanisms remain poorly understood, especially under anaerobic conditions used frequently in industry. Here we took a comparative approach to understand the response of to 1-butanol, isobutanol, or ethanol, across three genetic backgrounds of varying tolerance in aerobic and anaerobic conditions. We find that strains have different growth properties and alcohol tolerances with and without oxygen availability, as well as unique and common responses to each of the three alcohols. Our results provide evidence for strain-by-alcohol-by-oxygen interactions that moderate how cells respond to alcohol stress.
Topics: Aerobiosis; Alcohols; Gene Expression Regulation, Fungal; Gene-Environment Interaction; Saccharomyces cerevisiae; Transcriptome
PubMed: 30301737
DOI: 10.1534/g3.118.200677 -
Journal - Water Pollution Control... Jun 1972
Review
Topics: Aerobiosis; Government Agencies; Industrial Waste; Methods; Refuse Disposal; Water Pollution
PubMed: 4556340
DOI: No ID Found -
Biodegradation 2001For aerobic co-metabolism of chlorinated solvents to occur, it is necessary that oxygen, a primary substrate, and the chlorinated compound all be available to an... (Review)
Review
For aerobic co-metabolism of chlorinated solvents to occur, it is necessary that oxygen, a primary substrate, and the chlorinated compound all be available to an appropriate microorganism--that is, a microorganism capable of producing the nonspecific enzyme that will promote degradation of the contaminant while the primary substrate is aerobically metabolized. Thus, the transport processes that serve to mix the reactants are crucial in determining the rate and extent of biodegradation, particularly when considering in situ biodegradation. These transport processes intersect, at a range of scales, with the biochemical reactions. This paper reviews how the important processes contributing to aerobic co-metabolism of chlorinated solvents at different scales can be integrated into mathematical models. The application of these models to field-scale bioremediation is critically examined. It is demonstrated that modeling can be a useful tool in gaining insight into the physical, chemical, and biological processes relevant to aerobic co-metabolism, designing aerobic co-metabolic bioremediation systems, and predicting system performance. Research needs are identified that primarily relate to gaps in our current knowledge of inter-scale interactions.
Topics: Aerobiosis; Biological Transport; Chlorine Compounds; Models, Biological; Solvents
PubMed: 11710591
DOI: 10.1023/a:1012005406536 -
Annales Pharmaceutiques Francaises Jan 2011The present brief overview of the history of the development of our knowledge on cytochromes P450 (P450s) illustrates the spectacular progress that have been made on... (Review)
Review
Brief historical overview and recent progress on cytochromes P450: adaptation of aerobic organisms to their chemical environment and new mechanisms of prodrug bioactivation.
The present brief overview of the history of the development of our knowledge on cytochromes P450 (P450s) illustrates the spectacular progress that have been made on P450 mechanisms and structures especially during these last 20 years. Recently published structures of mammalian P450-substrate complexes have shown the great diversity of size, shape, and binding modes that are offered by the conformationally flexible substrate binding sites of xenobiotic-metabolizing P450s. They have also shown that these binding sites can adapt themselves to the great structural diversity of xenobiotics, to facilitate their oxidation and elimination. Our present detailed knowledge of the mechanisms and chemistry of P450s allows us to understand, at the molecular level, the origin of the various consequences of P450-dependent metabolism of drugs in pharmacology and toxicology. This is here illustrated by recent data on the detailed mechanism of bioactivation of the anti-thrombotic prodrugs ticlopidine, clopidogrel, and prasugrel.
Topics: Adaptation, Physiological; Aerobiosis; Animals; Biotransformation; Cytochrome P-450 Enzyme System; Environment; Fibrinolytic Agents; History, 20th Century; History, 21st Century; Humans; Prodrugs
PubMed: 21296219
DOI: 10.1016/j.pharma.2010.11.001 -
Journal of Applied Microbiology Apr 2006Campylobacter spp. continue to be the greatest cause of bacterial gastrointestinal infections in humans worldwide. They encounter many stresses in the host intestinal... (Review)
Review
Campylobacter spp. continue to be the greatest cause of bacterial gastrointestinal infections in humans worldwide. They encounter many stresses in the host intestinal tract, on foods and in the environment. However, in common with other enteric bacteria, they have developed survival mechanisms to overcome these stresses. Many of the survival mechanisms used by Campylobacter spp. differ from those used by other bacteria, such as Escherichia coli and Salmonella spp. This review summarizes the mechanisms by which Campylobacter spp. adapt to stress conditions and thereby increase their ability to survive on food and in the environment.
Topics: Adaptation, Physiological; Aerobiosis; Biodiversity; Biofilms; Campylobacter jejuni; Desiccation; Ecosystem; Food Microbiology; Gastrointestinal Tract; Humans; Signal Transduction
PubMed: 16553716
DOI: 10.1111/j.1365-2672.2006.02903.x -
Journal of Microbiology (Seoul, Korea) Apr 2008This review discusses critically what we know and would like to know about the microbiology of phosphorus (P) removal in activated sludge systems. In particular, the... (Review)
Review
This review discusses critically what we know and would like to know about the microbiology of phosphorus (P) removal in activated sludge systems. In particular, the description of the genome sequences of two strains of the polyphosphate accumulating organism found in these processes, Candidatus 'Accumulibacter phosphatis', allows us to address many of the previously unanswered questions relating to how these processes behave, and to raise new questions about the microbiology of P removal. This article attempts to be deliberately speculative, and inevitably subjective, but hopefully at the same time useful to those who have an active interest in these environmentally very important processes.
Topics: Aerobiosis; Anaerobiosis; Betaproteobacteria; Glycogen; Phosphorus; Sewage
PubMed: 18545960
DOI: 10.1007/s12275-008-0051-0 -
Chemosphere Oct 2021In this study, the strengthening effect of bio-carrier inoculation in the process of aerobic granulation and its influence on the microbial secretion of extracellular...
In this study, the strengthening effect of bio-carrier inoculation in the process of aerobic granulation and its influence on the microbial secretion of extracellular polymeric substances (EPS) has been systematically explored, to further understand and perfect the rapid granulation mechanism. Complete granulation was achieved within 15 days, and the granule morphology realized in a reactor inoculated with the bio-carrier (R1) was better than that in the control group (R2), in which complete granulation was not achieved during the entire operation period. However, AGS gradually disintegrated after the 20th day because of the strong shearing force, the crushed AGS enhanced granulation, however did not ensure stability. The average EPS content in R1 20 mg﹒gVSS higher than that in R2, and the protein (PN) content changes around 41.23-82.56 mg﹒gVSS during the granulation process. This indicates that the bio-carrier stimulates microorganisms to secrete more EPS, and PN may have a greater effect on the aggregation of microorganisms. The results showed that the addition of the bio-carrier shortened the AGS granulation time, and increased the EPS content, and the broken AGS played an auxiliary role as the nucleus for floc attachment.
Topics: Aerobiosis; Bioreactors; Extracellular Polymeric Substance Matrix; Sewage; Waste Disposal, Fluid
PubMed: 33971405
DOI: 10.1016/j.chemosphere.2021.130756 -
FEMS Microbiology Reviews Dec 2000Molecular oxygen is one of the most important reactants in biogeochemical cycles. Due to its low solubility in water, the consumption of oxygen leads to the development... (Review)
Review
Molecular oxygen is one of the most important reactants in biogeochemical cycles. Due to its low solubility in water, the consumption of oxygen leads to the development of oxic-anoxic interfaces, which separate aerobic from anaerobic processes in virtually all environments, ranging in scale from oceanic sediments to the fecal pellets of a small soil invertebrate. Three case studies were selected to illustrate the basic situation and the specific characteristics of oxic-anoxic interfaces: sediments, the rhizosphere of aquatic plants, and the intestinal tract of insects. Each system is governed by the same general principles, but striking differences arise from, e.g., the nature of the major microbial activities and the mechanisms controlling metabolite fluxes. Also scale and dimensional differences as well as the consequences of temporal fluctuations are of fundamental importance. Recent developments in microbial ecology, which often combine traditional and modern approaches, have significantly furthered our understanding of the specific microniches and the metabolic and behavioral adaptations of microorganisms to life at the oxic-anoxic interface. New concepts help to define the targets of future studies: the spatial organization of microbial populations, their microenvironments and in situ activities, and the functional interactions within structured microbial communities.
Topics: Adaptation, Physiological; Aerobiosis; Anaerobiosis; Animals; Bacteria; Intestines; Isoptera; Oxygen; Water Microbiology
PubMed: 11077159
DOI: 10.1111/j.1574-6976.2000.tb00567.x