scholarly journals Advances in the biological removal of sulphides from aqueous phase in anaerobic processes: A review

2016 ◽  
Vol 24 (1) ◽  
pp. 84-100 ◽  
Author(s):  
Lorna Guerrero ◽  
Silvio Montalvo ◽  
César Huiliñir ◽  
Jose Luis Campos ◽  
Andrea Barahona ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Hydrogen Sulphide ◽  
Microbial Fuel Cells ◽  
Anaerobic Processes ◽  
Biofilm Reactors ◽  
Anaerobic Reactors ◽  
Biological Removal ◽  
Chemical Factors ◽  
Biological Methods ◽  
Physical And Chemical

In this paper, we review the latest developments in biological methods used in the removal of hydrogen sulphide, present in the liquid phase in anaerobic reactors. The toxicity of H2S to methane-forming microorganisms and the problems caused by the presence of this compound in the biogas generated during this process, as well as the main causes of hydrogen sulphide generation in anaerobic processes of wastes are also reviewed. We especially discuss the fundamentals in applying micro-aerobic conditions to remove dissolved hydrogen sulphide from the aqueous phase of an anaerobic reactor. The alternative technology of simultaneous removal of sulphide, nitrate, and organic matter is under recent investigation. Therefore, this review paper includes a study and analysis of the microbiological basis of this technology, the physical and chemical factors that influence the process and the potential application of this technology on different types of wastewaters and situations. Also considered are the fundamentals of both biofilm reactors and microbial fuel cells desulphurization. Because relatively few studies on modeling desulphurisation processes are available, we discuss the advances made in that area.

Novel biological removal of hazardous chemicals at trace levels

2000 ◽  
Vol 42 (12) ◽  
pp. 49-60 ◽  
Author(s):  
P.L. McCarty
Keyword(s):  
Plug Flow ◽  
Chlorinated Solvents ◽  
Biological Removal ◽  
Sanitary Landfills ◽  
Low Levels ◽  
Trace Chemicals ◽  
Engineered Systems ◽  
Biological Methods ◽  
Aerobic And Anaerobic ◽  
Flow Treatment

Of recent concern is the removal of toxic compounds in wastewaters, soils, and groundwater to concentrations in the low microgram per litre level or less. Threshold limits to bioremediation exist and must be considered in biological treatment schemes to achieve such limits. These limits may be related to reaction kinetics or thermodynamics. Techniques for removing compounds below threshold levels exist that rely on appropriate approaches such as plug flow treatment. Novel biological methods exist for removal of refractory contaminants to low levels. Examples are provided for removal of trace levels of chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE), that employ dehalorespiration under anaerobic conditions or cometabolism under aerobic conditions. These approaches are currently being used in engineered systems or through natural attenuation for remediation of soils and groundwater. Successful results offer insights for similar removals of trace chemicals in both aerobic and anaerobic biological systems for treatment of wastewaters and sanitary landfills.

Biomedical Applications and Patents on Metallic Nanoparticles

2020 ◽  
Vol 10 ◽  
Author(s):  
Geetanjali Singh ◽  
Pramod Kumar Sharma ◽  
Rishabha Malviya
Keyword(s):  
Metallic Nanoparticles ◽  
Biomedical Applications ◽  
Size Range ◽  
Biomedical Application ◽  
Chemical Reduction ◽  
Chemical Methods ◽  
Future Challenges ◽  
Biological Methods ◽  
Cancer Diagnosis And Therapy ◽  
Physical And Chemical

Aim/Objective: The author writes the manuscript by reviewing the literatures related to the biomedical application of metallic nanoparticles. The term metal nanoparticles are used to describe the nanosized metals with the dimension within the size range of 1-100 nm. Methods: The preparation of metallic nanoparticles and their application is an influential area for research. Among various physical and chemical methods (viz. chemical reduction, thermal decomposition, etc.) for synthesizing silver nanoparticles, biological methods have been suggested as possible eco-friendly alternatives. The synthesis of metallic nanoparticles is having many problems inclusive of solvent toxicity, the formation of hazardous byproducts and consumption of energy. So it is important to design eco-friendly benign procedures for the synthesis of metallic nanoparticles. Results: From the literature survey, we concluded that metallic nanoparticles have applications in the treatment of different diseases. Metallic nanoparticles are having a great advantage in the detection of cancer, diagnosis, and therapy. And it can also have properties such as antifungal, antibacterial, anti-inflammatory, antiviral and anti-angiogenic. Conclusion: In this review, recent upcoming advancement of biomedical application of nanotechnology and their future challenges has been discussed.

Further Studies upon Chemical Factors Affecting the Breeding of Anopheles in Trinidad

1934 ◽  
Vol 25 (4) ◽  
pp. 491-494 ◽  
Author(s):  
P. A. Buxton
Keyword(s):  
Analytical Study ◽  
Chemical Constituents ◽  
Physical Factors ◽  
Factors Affecting ◽  
Early Stages ◽  
Freshwater Biology ◽  
Chemical Technique ◽  
Chemical Factors ◽  
Physical And Chemical

During the last decade, entomologists have made progress in understanding the environment in which certain insects live; in particular, we begin to understand the effect of certain physical and chemical factors, which make up a part of the environment. With this gain in knowledge, it is sometimes possible to forecast outbreaks of insects and of diseases conveyed by them, and one can sometimes say that a particular alteration of the environment will result in loss or gain. But so far as mosquitos are concerned, one must admit that though much work has been devoted to the analytical study of the water in which the early stages are passed, the results are disappointing. A consideration of the published work suggests several reasons for this. Investigation into the ecology of the mosquito has had a vogue, and much of it has been done by workers who were isolated and whose knowledge of chemical technique and freshwater biology was limited. Apart from that, the inherent difficulties are great, for the worker must hunt for the limiting chemical and physical factors among a host of others which are doubtless unimportant, and there are few clues to indicate which of the chemical constituents of the water affects the mosquito. The data are therefore voluminous and it is difficult to reduce them to order and present them so that they can be readily understood.

Menadione nicotinamide bisulphite as a source of vitamin K and niacin activities for the growing pig

2000 ◽  
Vol 71 (1) ◽  
pp. 111-117 ◽  
Author(s):  
M. Marchetti ◽  
M. Tassinari ◽  
S. Marchetti
Keyword(s):  
Vitamin K ◽  
Control Diet ◽  
Live Weight ◽  
Organic Salt ◽  
Free Form ◽  
Food Supplementation ◽  
Sodium Bisulphite ◽  
Chemical Factors ◽  
And Control ◽  
Physical And Chemical

AbstractWhen compared with other menadione derivatives such as menadione sodium bisulphite (MSB), menadione nicotinamide bisulphite (MNB), an organic salt combining menadione and nicotinamide, shows better stability towards physical and chemical factors once it is added to pre-mixes or foods. The present work evaluates the bioavailability of the two vitamins present in this compound and toxicity in the pig. To assess vitamin bioavailability, pigs were given small amounts of food containing MNB or equivalent amounts of MSB and nicotinamide in the free form. Menadione and nicotinamide concentrations in blood samples drawn at set times after the diets were given did not reveal any significant differences between the two modes of administration. Haematic levels of both vitamins in animals receiving MNB, or MSB and nicotinamide, were after 2, 4, 8 and 12 h higher (P < 0·001) than those of untreated animals. The tolerance level to MNB was evaluated in pigs given diets containing graded amounts of MNB (100, 500, 2500 mg/kg) for 28 days. No significant (P > 0·05) differences were recorded in live weight, food intake and gain/food ratio in pigs given these diets when compared with those given an unsupplemented diet. Haemoglobin and bilirubin levels did not differ between animals given various amounts of MNB and control animals. Plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in pigs given 100 mg/kg of MNB did not show significant differences when compared with those observed in pigs given an unsupplemented control diet. In pigs on the diets supplemented with 500 and 2500 mg/kg of MNB there was a significant increase in the two enzymatic activities as compared with controls (P < 0·001 and P < 0·01). In the case of ALT this had disappeared by 28 weeks. MNB is a good source of vitamin K for the pig and does not appear to have any adverse effects, even when administered at levels higher than those normally used in pig food supplementation.

The Qualitative and Quantitative Distribution of Plankton in the Strait of Georgia in Relation to Certain Oceanographic Factors

1957 ◽  
Vol 14 (4) ◽  
pp. 521-552 ◽  
Author(s):  
Joseph Eugène Henri Légaré
Keyword(s):  
Salinity Gradient ◽  
General Distribution ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Quantitative Distribution ◽  
Qualitative And Quantitative ◽  
Chemical Factors ◽  
Physical And Chemical ◽  
Plankton Communities ◽  
Made In

In order to gain some picture of the seasonal variations in the plankton communities two cruises were made in the Strait of Georgia, one in June 1955, and the other in November 1955; 165 plankton collections were taken, also surface temperatures.The correlation of these data have resulted in a number of conclusions concerning the distribution of plankton in the Strait of Georgia. The chief factor affecting the general distribution of plankton is the salinity gradient. The inflow of fresh water from the Fraser River forms zones of varying properties, and leads to the development of different plankton communities. The extent to which physical and chemical factors may determine the presence or absence of certain organisms from the zones described is discussed.

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