Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading

2008 ◽  
Vol 58 (2) ◽  
pp. 399-405 ◽  
Author(s):  
P. E. Molokwane ◽  
C. K. Meli ◽  
E. M. N. Chirwa
Keyword(s):  
North America ◽  
Reduction Rate ◽  
Treatment Plant ◽  
Complete Removal ◽  
Anaerobic Conditions ◽  
High Concentration ◽  
Gram Negative ◽  
High Chromium ◽  
North West ◽  
Chromium Vi

A mixed-culture of bacteria collected from a wastewater treatment plant in Brits, North-West Province (South Africa) biocatalytically reduced Cr(VI) at much higher concentrations than previously observed in cultures isolated in North America. Complete Cr(VI) reduction in aerobic cultures was achieved at a high concentration of 200 mg/L after incubation for only 65 hours. Under anaerobic conditions up to 150 mg, Cr(VI)/L was completely removed after incubating for 130 to 155 hours, still higher than the Cr(VI) reduction achieved with previous cultures where complete removal was only observed in cultures with the added Cr(VI) concentration not greater than 30 mg/L. Cr(VI) reduction capability of the cultures was verified in purified cultures. Consortium cultures were characterised using 16S rRNA partial sequence analysis. Results showed that the gram-positive Bacillus genera predominated under aerobic conditions with a small composition of the gram-negative Microbacterium sp. There was more biodiversity observed in the anaerobic cultures with the marked appearance of Enterococcus, Arthrobacter, Paenibacillus and Oceanobacillus species. The results showed that Cr(VI) reduction rate in the new culture was up to eight times higher than that previously observed in other Cr(VI) reducing cultures isolated from Cr(VI) contaminated soil environments in Newark (New Jersey) and other sites in North America.

The significance of microbial Fe(III) reduction in the activated sludge process

1996 ◽  
Vol 34 (5-6) ◽  
pp. 129-136 ◽  
Author(s):  
Per Halkjær Nielsen
Keyword(s):  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Reduction Rate ◽  
Treatment Plant ◽  
Anaerobic Conditions ◽  
Phosphate Release ◽  
Floc Structure ◽  
Acetate Formation ◽  
Nitrate And Nitrite ◽  
P Removal

The significance of microbial Fe(III) reduction in activated sludge was evaluated with regard to: its importance as electron acceptor; as a producer of acetate during anaerobic conditions; for phosphate release; and for its role in the floc structure. Potential Fe(III) reduction rates were measured in 6 wastewater treatment plants with and without biological P-removal and found to be in the range of 0.9-5.4 mgFe/gVSS h. Assuming an incomplete oxidation of organic matter leading to acetate formation, Fe(III) reduction was a major acetate source, providing substrate to phosphorus-accumulating organisms (PAO) during anaerobic conditions. The observed high potential Fe(III) reduction rate might also be responsible for a significant chemical phosphate release due to reduction of Fe(III) to Fe(II) in clarifies, sludge storage tanks and anaerobic tanks in plants with biological P-removal. Investigation of the concentrations of Fe(II) in a full-scale treatment plant in anaerobic tanks, oxic/anoxic tanks and return sludge indicated that both reduction and reoxidation took place in the treatment plant. Reoxidation of Fe(II) to Fe(III) in activated sludge was shown to take place with oxygen and probably also during anoxic conditions with nitrate and nitrite as electron acceptors. The results indicate that Fe may be more involved in important processes in activated sludge than hitherto assumed, so a better understanding of Fe interactions in activated sludge is desirable.

Nitrogen Reduction – Volume Demand

1992 ◽  
Vol 25 (4-5) ◽  
pp. 233-240
Author(s):  
T. Palmgren
Keyword(s):  
Suspended Solids ◽  
Age Factors ◽  
Reduction Rate ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Aeration Tank ◽  
Nitrogen Reduction ◽  
Solids Concentration ◽  
Yearly Average ◽  
Nitrification Process

Due to the slow growth of nitrification bacteria at low temperatures, nitrogen reduction normally requires long hydraulic retention time during winter. Important for the nitrification process is the aerated sludge age. Factors influencing the sludge age are aerated volume, mixed liquor suspended solids concentration, organic loading and sludge yield. In an existing plant you cannot easily expand the volume and the load is difficult to decrease. But the suspended solids concentration can be increased by running the biological step with the contact stabilisation process. At the Käppala Association sewage treatment plant in Lidingö just outside Stockholm, one of the six aeration tanks has been reconstructed for full scale nitrogen removal experiments. In this tank the old aeration system has been replaced with rubber membrane diffusers. Further more there are several zones separated by walls in the tank. The tank can thereby be run with great flexibility. By running it with the contact stabilisation process, the sludge age has been improved by a factor between 1.5 and 2 and thereby it succeeds in keeping the nitrification bacteria in the system even during snow melting. At temperatures of about 9 °C and hydraulic retention times of less than 3 hours in the contact zone there has been a nitrification degree of up to 50 to 60 %. The experiment was conducted with a stabilisation zone of up to half the total volume of the aeration tank. The main purpose for the experiments during the winter seasons was to improve nitrification. Keeping the nitrifiers in the system had been a crucial problem during previous years. When the nitrifiers were lost with an increased flow and decreased temperature the nitrification process didn't restart until the temperature was increased and the load decreased. Usually this didn't occur until the middle of the summer meaning a loss of nitrification for up to six months. In Sweden there is a goal set for 50 % nitrogen reduction for the plants in the Stockholm region. At Käppala we manage to keep 60 to 70 % nitrogen reduction during the warm season, that is from July to December. If we can keep up the nitrification the whole year we can achieve 50 % as a yearly average under normal conditions even though we can't keep the nitrogen reduction rate as high during the cold season.

Vancomycin Adsorption During in vitro Model of Hemoperfusion with HA380 Cartridge

Nephron ◽  
2021 ◽  
pp. 1-7
Author(s):  
Ilaria Godi ◽  
Anna Lorenzin ◽  
Silvia De Rosa ◽  
Gianlorenzo Golino ◽  
Maira Knust ◽  
...  
Keyword(s):  
Complete Removal ◽  
Potential Interaction ◽  
Blood Purification ◽  
Therapeutic Monitoring ◽  
High Concentration ◽  
Langmuir Isotherm Model ◽  
Vitro Model ◽  
Kinetics Of ◽  
Balanced Solution

<b><i>Introduction:</i></b> A critical point for using blood purification during sepsis may be the potential interaction with antimicrobial therapy, the mainstay of sepsis treatment. The aim of our study was to investigate the vancomycin removal during hemoperfusion (HP) using HA380 cartridge. <b><i>Methods:</i></b> This is an experimental study, in which 500 mL of solution was circulated in a closed-circuit (blood flow of 250 mL/min) simulating HP ran using HA380. Vancomycin was added to reach a through concentration or a very high concentration to evaluate the removal ratio (RR) during 120 min of HP. Comparison between blood-crystalloid solution and balanced solution was performed by using Kruskal-Wallis test. The kinetics of vancomycin removal and the adsorption isotherm were evaluated. <b><i>Results:</i></b> We found a complete removal of vancomycin at baseline through concentration of 23.0 ± 7.4 mg/L. Using extremely high concentration (baseline 777.0 ± 62.2 mg/L), RR was 90.1 ± 0.6% at 5 min and 99.2 ± 0.6% at 120 min. No difference in terms of RR was found between blood-crystalloid mixture and balanced solution. The kinetics of the vancomycin reduction followed an exponential decay. Repeated boluses (total amount of 2,000 mg) resulted in cumulative adsorption of 1,919.4 mg with RR of 96.6 ± 1.4%, regardless of the amount injected (100 vs. 500 mg). Vancomycin adsorption onto HA380 followed the Langmuir isotherm model. <b><i>Conclusions:</i></b> A considerable amount of vancomycin was rapidly removed during in vitro HP with HA380. Clinical studies are needed to determine whether this may lead to underdosing. Drug therapeutic monitoring is highly recommended when using HA380 for blood purification in patients receiving vancomycin.

Japewia Subaurifera, A New Lichen Genus and Species From North-West Europe and Western North America

1990 ◽  
Vol 22 (3) ◽  
pp. 205-212 ◽  
Author(s):  
T. Tønsberg
Keyword(s):  
British Columbia ◽  
North America ◽  
Western North America ◽  
Coniferous Trees ◽  
North West

AbstractThe genus Japewia Tønsb. is introduced to accommodate three species including J. subaurifera Muhr & Tønsb. sp. nov. based on material from Norway, Sweden, Finland, Scotland, Canada (British Columbia) and U.S.A. (Washington). This species is closely related to Lecidea tornoensis Nyl. but is distinguished in being sorediate and by the production of lobaric acid (accessory) and acetone-soluble pigments. It grows on bark of deciduous and coniferous trees. Lecidea carrollii Coppins & P. James and L. tornoensis Nyl. are transferred to Japewia.

Kinetics of growth and multi substrate degradation by an indigenous mixed microbial culture isolated from a wastewater treatment plant in Guwahati, India

2008 ◽  
Vol 58 (5) ◽  
pp. 1101-1106
Author(s):  
Pichiah Saravanan ◽  
K. Pakshirajan ◽  
P. K. Saha
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Lag Phase ◽  
Microbial Culture ◽  
High Concentration ◽  
Mixed Microbial Culture ◽  
Phenol Biodegradation ◽  
Low Concentration ◽  
Culture Growth

An indigenous mixed culture of microorganisms, isolated from a sewage treatment plant, was investigated for its potential to simultaneously degrade phenol and m-cresol during its growth in batch shake flasks. 22 full factorial designs with the two substrates as the factors, at two different levels and two different initial concentration ranges, were employed to carry out the biodegradation experiments. For complete utilisation of phenol and m-cresol, the culture took a minimum duration of 21 hrs at their low concentration of 100 mg/L each, and a maximum duration of 187 hrs at high concentration of 600 mg/L each in the multisubstrate system. The biodegradation results also showed that the presence of phenol in low concentration range (100–300 mg/L did not inhibit m-cresol biodegradation; on the other hand, presence of m-cresol inhibited phenol biodegradation by the culture. Moreover, irrespective of the concentrations used, phenol was degraded preferentially and earlier than m-cresol. During the culture growth, a lag phase was observed above a combined concentration of 500 mg/L i.e., 200 mg/L m-cresol and 300 mg/L of phenol and above). Statistical analysis of the specific growth rate of the culture in the multisubstrate system was also performed in the form of ANOVA and Student ‘t’ test, which gave good interpretation in terms of main and interaction effects of the substrates.

scholarly journals II.—On Solenopora garwoodi, sp. nov., from the Lower Carboniferous in the North-West of England

1913 ◽  
Vol 10 (7) ◽  
pp. 289-292 ◽  
Author(s):  
George J. Hinde
Keyword(s):  
North America ◽  
Calcareous Algae ◽  
Lower Carboniferous ◽  
North West ◽  
The North ◽  
Jurassic Rocks

Some years since Professor E. J. Garwood sent to me for examination some pieces of limestone from the Lower Carboniferous rocks in the Shap and Ravenstonedale districts of Westmorland, in which he had observed the rounded outlines of fossils with a structure which appeared to him to resemble that of Stromatopora. The rock in which the fossils were embedded was so compact and hard that they could not be extracted, and it was necessary to make sections in various directions in order to ascertain their structure, which proved to be identical with that of Solenopora, now well known as one of the calcareous Algæ. It is many years ago since this genus was recognized in the Ordovician rocks in North America, Britain, and Eussia; more recently it was found in the Silurian rocks of the Isle of Gotland, and in 1894 a species was described from the Jurassic rocks of Gloucestershire and Yorkshire. But until this fortunate discovery of its occurrence in the Lower Carboniferous by Professor Garwood, no example of the genus was known in any of the rocks between the Silurian and the Jurassic.

scholarly journals Efficiency of Biological Phosphorus Removal by Filamentous Bacteria

2016 ◽  
Vol 21 (1-2) ◽  
pp. 117-123 ◽  
Author(s):  
Alicja Machnicka ◽  
Klaudiusz Grübel
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Water Environment ◽  
Treatment Plant ◽  
Chemical Precipitation ◽  
Heterogeneous Structure ◽  
Filamentous Bacteria ◽  
Biological Phosphorus Removal ◽  
High Concentration ◽  
Sludge Flocs

AbstractPhosphorus removal in wastewater treatment plant is carried out by chemical precipitation, advanced biological treatment or a combination of both. One of the biggest problems with high concentration of phosphorus in water environment is eutrophication. Activated sludge flocs have a heterogeneous structure, which consist of a variety of microorganisms. Filamentous bacteria are normally present in the activated sludge and have ability to assimilation of phosphorus. In this study phosphorus accumulation by isolated filamentous bacteria from activated sludge foam was present.

scholarly journals Electrochemical Removal of Chromium (VI) from Wastewater

2019 ◽  
Author(s):  
Hao Peng ◽  
Yumeng Leng ◽  
Jing Guo
Keyword(s):  
Reaction Temperature ◽  
Current Density ◽  
Reduction Rate ◽  
Reduction Process ◽  
Order Equation ◽  
First Order ◽  
Chromium Vi ◽  
Reduction Efficiency ◽  
Pseudo First Order ◽  
Electrochemical Removal

Removal of hexavalent chromium had attracted much more attention as it was a hazardous contaminant. Electrochemical reduction technology was applied to removal chromium (VI) from wastewater. The mechanism and parameters affect the reduction process were investigated. The results showed that the reduction efficiency was significantly affected by the concentration of H2SO4, current density and reaction temperature. And the reduction efficiency was up to 86.45% at concentration of H2SO4 of 100g/L, reaction temperature of 70 ℃, current density at 50 A/m2, reaction time at 180 min and stirring rate of 500 rpm. The reduction process of chromium (VI) was followed pseudo-first-order equation, and the reduction rate could be expressed as Kobs = k [H2SO4]1• [j] 4•exp-4170/RT.

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