Anaerobic oxidation of cholesterol by a denitrifying enrichment

2001 ◽  
Vol 44 (4) ◽  
pp. 145-150 ◽  
Author(s):  
E. Barrandeguy ◽  
S. Tarlera
Keyword(s):  
Anaerobic Treatment ◽  
Organic Load ◽  
Cholesterol Oxidation ◽  
Nitrite Accumulation ◽  
Reactor Performance ◽  
Nitrogen Gas ◽  
Carbon And Nitrogen ◽  
Rdna Sequences ◽  
16S Rdna Sequences ◽  
The One

Sterols (e.g. cholesterol) present in wool scouring effluent represent the most recalcitrant fraction in anaerobic treatment. This study was conducted to examine the feasibility of removal of this organic load through a denitrifying post-treatment stage. A stable cholesterol-denitrifying enrichment (CHOL-1) was obtained from sludge of a bench-scale upflow sludge bed (USB) denitrifying reactor integrated to a carbon and nitrogen removal system for sanitary landfill leachate. According to the amounts of cholesterol degraded and of nitrite and nitrogen gas formed, the capacity for complete cholesterol oxidation under anaerobic conditions by CHOL-1 can be assumed. Nitrite accumulation observed at a low C/N ratio outlines the importance of determining the optimal C/N ratio for adequate denitrifying reactor performance. The enrichment was partly identified with molecular analysis of cloned 16S rDNA sequences revealing the presence of two groups of bacteria belonging to the β subclass of the Proteobacteria. According to analysis of sequences, it can be inferred that a yet uncultivated new bacterium is the one responsible for cholesterol oxidation. Results of this study suggest that sludge from a denitrifying reactor treating leachate is potentially useful in a combined anaerobic-anoxic system for degradation of cholesterol that remains after methanogenic treatment.

Evaluation of an anaerobic/aerobic system for carbon and nitrogen removal in slaughterhouse wastewater

2001 ◽  
Vol 44 (4) ◽  
pp. 271-277 ◽  
Author(s):  
L. A. Núñez ◽  
B. Martínez
Keyword(s):  
Total Nitrogen ◽  
Nitrogen Removal ◽  
Uasb Reactor ◽  
Nitrite Accumulation ◽  
Nitrogen Gas ◽  
Active Biomass ◽  
Slaughterhouse Wastewater ◽  
Carbon And Nitrogen ◽  
Activated Sludge Reactor ◽  
Removal Efficiencies

In this work the performance of an anaerobic UASB reactor coupled with an activated sludge reactor for carbon and nitrogen removal in slaughterhouse wastewater is investigated. Periods with and without recirculation of aerobic effluent over 165 days are analysed. Working with a recirculation ratio of 2, removal efficiencies up to 90% and 65% are obtained for DQO and total nitrogen (TN), respectively. Higher recirculation ratios caused severe washout of active biomass in both reactors due to the high hydraulic loading rates applied. Denitrification in the UASB reactor was complete, with no nitrite accumulation and mainly to nitrogen gas. Significant decreases in COD removal efficiencies in the UASB reactor were observed at recirculation ratio of 2. Sudden decreases in total nitrogen efficiencies were related to inhibition process of nitrifying microorganisms, especially at high recirculation ratios.

scholarly journals Detection and Isolation of Novel Rhizopine-Catabolizing Bacteria from the Environment

1998 ◽  
Vol 64 (12) ◽  
pp. 4944-4949 ◽  
Author(s):  
Brian B. McSpadden Gardener ◽  
Frans J. de Bruijn
Keyword(s):  
Dna Sequences ◽  
Sinorhizobium Meliloti ◽  
Southern Hybridization ◽  
Southern Hybridization Analysis ◽  
Carbon And Nitrogen ◽  
Rdna Sequences ◽  
16S Rdna Sequences ◽  
Standard Assay ◽  
Ribosomal Dnas ◽  
Assay Conditions

ABSTRACT Microbial rhizopine-catabolizing (Moc) activity was detected in serial dilutions of soil and rhizosphere washes. The activity observed generally ranged between 106 and 107 catabolic units per g, and the numbers of nonspecific culture-forming units were found to be approximately 10 times higher. A diverse set of 37 isolates was obtained by enrichment on scyllo-inosamine-containing media. However, none of the bacteria that were isolated were found to contain DNA sequences homologous to the known mocA,mocB, and mocC genes of Sinorhizobium meliloti L5-30. Twenty-one of the isolates could utilize an SI preparation as the sole carbon and nitrogen source for growth. Partial sequencing of 16S ribosomal DNAs (rDNAs) amplified from these strains indicated that five distinct bacterial genera (Arthrobacter, Sinorhizobium,Pseudomonas, Aeromonas, andAlcaligenes) were represented in this set. Only 6 of these 21 isolates could catabolize 3-O-methyl-scyllo-inosamine under standard assay conditions. Two of these, strains D1 and R3, were found to have 16S rDNA sequences very similar to those of Sinorhizobium meliloti. However, these strains are not symbiotically effective on Medicago sativa, and DNA sequences homologous to thenodB and nodC genes were not detected in strains D1 and R3 by Southern hybridization analysis.

The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity

1998 ◽  
Vol 38 (4-5) ◽  
pp. 29-35 ◽  
Author(s):  
C. J. Banks ◽  
P. N. Humphreys
Keyword(s):  
Ph Control ◽  
Anaerobic Treatment ◽  
Buffering Capacity ◽  
Single Stage ◽  
Stable Operation ◽  
Reactor Performance ◽  
Two Stage ◽  
Ph Buffering ◽  
Stage System ◽  
The Stability

The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.

scholarly journals The phylogeny of the genusYersiniabased on 16S rDNA sequences

1993 ◽  
Vol 114 (2) ◽  
pp. 173-177 ◽  
Author(s):  
A. Ibrahim ◽  
B.M. Goebel ◽  
W. Liesack ◽  
M. Griffiths ◽  
E. Stackebrandt
Keyword(s):  
16S Rdna ◽  
Rdna Sequences ◽  
16S Rdna Sequences

scholarly journals Assessment of trophic relationships between symbiotic tropical ophiuroids using C and N stable isotope analysis

2006 ◽  
Vol 86 (6) ◽  
pp. 1443-1447 ◽  
Author(s):  
D. Fourgon ◽  
G. Lepoint ◽  
I. Eeckhaut
Keyword(s):  
Stable Isotopes ◽  
Potential Benefit ◽  
Feeding Habits ◽  
Isotope Analysis ◽  
Tracer Experiment ◽  
Trophic Relationships ◽  
Nitrogen Stable Isotopes ◽  
Carbon And Nitrogen ◽  
C And N ◽  
The One

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiuroids, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiuroids. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate δ13C values between both adult species. The high proportion of 13C in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston from their associated host, O. scolopendrina.

scholarly journals Development of anammox reactor equipped with a degassing membrane to improve biomass retention

2012 ◽  
Vol 66 (2) ◽  
pp. 451-456 ◽  
Author(s):  
Kosuke Matsunaga ◽  
Tomonori Kindaichi ◽  
Noriatsu Ozaki ◽  
Akiyoshi Ohashi ◽  
Yoshihito Nakahara ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
N2o Emission ◽  
Anammox Bacteria ◽  
Component Ratio ◽  
Reactor Performance ◽  
Contributing Factors ◽  
Nitrogen Gas ◽  
Biomass Retention ◽  
Gas Selectivity

In up-flow anammox reactors, one of the contributing factors to biomass wash-out is the adherence of nitrogen gas produced by the anammox reaction to biomass. In this study, we operated an up-flow anammox reactor equipped with a degassing membrane to minimize the biomass wash-out from the reactor by separating the produced gas from the biomass. In addition, both the effect of degassing on the anammox reactor performance and the durability of the membrane submerged in the anammox reactor were investigated. The results show that the use of the degassing membrane in the anammox reactor could (1) improve the biomass retention ability (by separating the produced gas from the biomass), and (2) increase the component ratio of anammox bacteria in the reactor. In addition, degassing could reduce the N2O emission produced in the reactor (for the gas selectivity of the degassing membrane). No membrane fouling was observed even after 2 months of operation without washing, indicating an advantage to the use of the degassing membrane.

scholarly journals The burying and grazing effects of plateau pika on alpine grassland are small: a pilot study in a semiarid basin on the Qinghai-Tibet Plateau

2016 ◽  
Vol 13 (22) ◽  
pp. 6273-6284 ◽  
Author(s):  
Shuhua Yi ◽  
Jianjun Chen ◽  
Yu Qin ◽  
Gaowei Xu
Keyword(s):  
Net Primary Production ◽  
Keystone Species ◽  
Alpine Grassland ◽  
Tibet Plateau ◽  
Plateau Pika ◽  
Carbon And Nitrogen ◽  
Grazing Effects ◽  
Considerable Controversy ◽  
The One ◽  
Qinghai Tibet Plateau

Abstract. There is considerable controversy about the effects of plateau pika (Ochotona curzoniae, hereafter pika) on alpine grassland on the Qinghai-Tibet Plateau (QTP). On the one hand, pika is considered a keystone species. On the other hand, it is being poisoned. Although significant efforts have been made to study the effects of pika at a quadrat scale ( ∼  m2), our knowledge about its distribution and effects at a larger scale is very limited. In this study, we investigated the direct effects, i.e., burying and grazing, of pika by upscaling field sampling at a quadrat scale to a plot scale ( ∼  1000 m2) by aerial photographing. Altogether 168 plots were set on four different types of alpine grassland in a semiarid basin on the QTP. Results showed that (1) the effects of pika pile burying on the reduction of vegetation cover, biomass, soil carbon, and nitrogen were less than 10 %, which was much smaller than the effects of bald patches; and (2) pika consumed 8–21 % of annual net primary production of grassland. We concluded that the direct burying and grazing effects of pika on alpine grassland were minor in this region. The quadcopter is an efficient and economic tool for long-term repeated monitoring over large regions for further understanding the role of pika.

Floating geomembrane covers for odour control and biogas collection and utilization in municipal lagoons

2000 ◽  
Vol 42 (10-11) ◽  
pp. 291-298 ◽  
Author(s):  
C. J. DeGarie ◽  
T. Crapper ◽  
B. M. Howe ◽  
B. F. Burke ◽  
P. J. McCarthy
Keyword(s):  
Control System ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Anaerobic Treatment ◽  
Organic Load ◽  
Stabilization Pond ◽  
Waste Stabilization ◽  
Odour Control ◽  
Lagoon Systems ◽  
Anaerobic Lagoons

The use of anaerobic lagoons as the first pond in waste stabilization pond systems in tropical and warm-temperature climates is considered a highly cost-effective and practical way to treat municipal wastewater. These anaerobic ponds, designed with hydraulic residence times of up to six days, can effect BOD5 removals of 60 to 80%. The subsequent aerobic stabilization pond surface area is greatly reduced over systems designed without anaerobic treatment up front due to the organic load reduction occurring anaerobically. In lagoon systems with mechanical aeration, operation costs can be greatly reduced. While odour is a concern with anaerobic treatment, anaerobic ponds treating municipal wastewater can be designed to be relatively odour-free given sufficiently low wastewater sulfate concentrations. However, when sulfate concentrations are high, or when odour control or greenhouse gas emissions are significant issues, or when the wastewater is relatively high in organic strength resulting in commercial production of methane gas, anaerobic lagoons can be covered, and the biogas collected and burned both to produce energy and reduce emissions and odour. The City of Melbourne treats approximately 50% of its municipal wastewater at the Western Treatment Plant in waste stabilization ponds designed with anaerobic ponds as the first pond in the system. Each of three pond systems at the Western Treatment Plant receives an average dry weather flow of 120,000 m3/d with an average strength of 400 mg/L BOD5. This paper describes the design, installation and commissioning of two 3.9 hectare floating, self draining, geomembrane covers on the anaerobic section of two of these lagoon systems. Biogas collection and utilization were an important part of the installation. A description of how the biogas is collected, the quantities generated and an overview of the control system used to operate the biogas handling facility is also included. Particular emphasis was placed on maximizing biogas utilization in design of the biogas control system.

Characterization, Digestibility and Anaerobic Treatment of Leachates from Old and Young Landfills

1989 ◽  
Vol 21 (4-5) ◽  
pp. 145-155 ◽  
Author(s):  
R. Méndez ◽  
J. M. Lema ◽  
R. Blázquez ◽  
M. Pan ◽  
C. Forjan
Keyword(s):  
Anaerobic Digestion ◽  
Anaerobic Treatment ◽  
Full Scale ◽  
Operating Conditions ◽  
Organic Load ◽  
Anaerobic Filter ◽  
Standards Of Living ◽  
Landfill Sites

We have evaluated the utility of applying anaerobic digestion treatment to the leachates from two landfill sites receiving solid urban refuse from populations of similar standards of living. Both tips are located in the same area and have very similar climates, but they differ as regards the length of time they have been operated. The leachates from the older tip have much lower levels of organic load, 40% of which was refractory to the anaerobic digestion treatment applied. The digestibility of leachates was studied by using a semicontinuous suspended sludge system.It was possible to remove up to 65% of the soluble COD of leachates from the young tip by means of an anaerobic filter working at HRTs less than 2 days. This system proved to be highly stable when its operating conditions were subjected to perturbations similar to those likely to be suffered by a full-scale plant.

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