Good laboratory Practice for Microbiology
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Effects of Heavy Metals on Cell Density, Size, Specific Growth Rate and Chlorophyll a of Tetraselmis Tetrathele Under Controlled Laboratory Conditions
Abstract
The effects of the varying levels of mercury (Hg) and cadmium (Cd) (0, 0.1, 0.3, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mg L⁻¹) to the cellular density of the green microalgae Tetraselmis tetrathele were evaluated every 24 h for 120 h. Specific growth rate, cell sizes and chlorophyll a were also monitored in the 5.0 mg L⁻¹ Hg and Cd and were compared to the unexposed at 0, 12, 24, 36, 48 and 120h. Results showed that the algal density of T. tetrathele exposed to various levels of Hg were similar with the control up to 48 h. Variations on different concentrations at different times were observed but the results suggest that T. tetrathele was not affected by Hg even at concentrations up to 5.0 mg L⁻¹ for 48 h but started to show toxicity from 3.0 to 5.0 mg L⁻¹ after 72 h and longer. Cd on the other hand also showed toxicity at 3.0, 4.0 and 5.0 mg L⁻¹ beyond 24 h exposure. The specific growth rate of T. tetrathele exposed to both 5.0 mg L⁻¹ Hg and Cd was statistically similar with those of the unexposed from 0 to 12 h and negative growth rates then followed up to 36 h. The chlorophyll a was significantly lower in the metal -exposed algae than did those unexposed. Chlorophyll a also decreased in T. tetrathele exposed to both heavy metals but algal cell sizes were not affected with the presence of Hg or Cd in the culture system.
Effects of Heavy Metals on Cell Density, Size, Specific Growth Rate and Chlorophyll a of Tetraselmis Tetrathele Under Controlled Laboratory Conditions
Abstract
The effects of the varying levels of mercury (Hg) and cadmium (Cd) (0, 0.1, 0.3, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mg L⁻¹) to the cellular density of the green microalgae Tetraselmis tetrathele were evaluated every 24 h for 120 h. Specific growth rate, cell sizes and chlorophyll a were also monitored in the 5.0 mg L⁻¹ Hg and Cd and were compared to the unexposed at 0, 12, 24, 36, 48 and 120h. Results showed that the algal density of T. tetrathele exposed to various levels of Hg were similar with the control up to 48 h. Variations on different concentrations at different times were observed but the results suggest that T. tetrathele was not affected by Hg even at concentrations up to 5.0 mg L⁻¹ for 48 h but started to show toxicity from 3.0 to 5.0 mg L⁻¹ after 72 h and longer. Cd on the other hand also showed toxicity at 3.0, 4.0 and 5.0 mg L⁻¹ beyond 24 h exposure. The specific growth rate of T. tetrathele exposed to both 5.0 mg L⁻¹ Hg and Cd was statistically similar with those of the unexposed from 0 to 12 h and negative growth rates then followed up to 36 h. The chlorophyll a was significantly lower in the metal -exposed algae than did those unexposed. Chlorophyll a also decreased in T. tetrathele exposed to both heavy metals but algal cell sizes were not affected with the presence of Hg or Cd in the culture system.
Boiler Water Quality Requirements and Associated Steam Quality for Industrial/Commercial and Institutional Boilers
Introduction:
The purpose of this publication is to acquaint engineers, purchasers and operators of industrial, commercial and institutional (ICI) boilers with ABMA's judgment as to the relationship between boiler water quality and boiler performance. This document is published for general guidance as a supplement to detailed operating manuals supplied by the equipment manufacturers. It should also be noted that the information presented is directed to steel boiler designs, as opposed to cast iron sectional or copper finned tube boilers. Furthermore Utility Boilers and Combined Cycle Boilers, which require extremely close control of water quality and steam purity, are not the topic of this document. This new document combines two previous ABMA Guideline documents, namely “Boiler Water Requirements and Associated Steam Purity for Commercial Boilers” (1998), and “Boiler Water Limits and Achievable Steam Purity for Water tube Boilers”, (1995). The document discusses the effect of various feed water and condensate systems on the boiler operation. It also provides information on boiler water and steam testing as well as system care and maintenance. It is recognized that specific boiler usage and water treatment will vary and may require values different from these recommendations. Boiler users therefore, need to define limits, equipment and operating parameters for their particular application. These recommendations are for information only. Everyone is free to accept or reject the conclusions of these suggestions as their own judgment warrants in all aspects of the conduct of their business. The ABMA does not represent or warrant that any level of steam purity depicted will be achieved by any particular boiler or boilers.
Boiler Water Quality Requirements and Associated Steam Quality for Industrial/Commercial and Institutional Boilers
Introduction:
The purpose of this publication is to acquaint engineers, purchasers and operators of industrial, commercial and institutional (ICI) boilers with ABMA's judgment as to the relationship between boiler water quality and boiler performance. This document is published for general guidance as a supplement to detailed operating manuals supplied by the equipment manufacturers. It should also be noted that the information presented is directed to steel boiler designs, as opposed to cast iron sectional or copper finned tube boilers. Furthermore Utility Boilers and Combined Cycle Boilers, which require extremely close control of water quality and steam purity, are not the topic of this document. This new document combines two previous ABMA Guideline documents, namely “Boiler Water Requirements and Associated Steam Purity for Commercial Boilers” (1998), and “Boiler Water Limits and Achievable Steam Purity for Water tube Boilers”, (1995). The document discusses the effect of various feed water and condensate systems on the boiler operation. It also provides information on boiler water and steam testing as well as system care and maintenance. It is recognized that specific boiler usage and water treatment will vary and may require values different from these recommendations. Boiler users therefore, need to define limits, equipment and operating parameters for their particular application. These recommendations are for information only. Everyone is free to accept or reject the conclusions of these suggestions as their own judgment warrants in all aspects of the conduct of their business. The ABMA does not represent or warrant that any level of steam purity depicted will be achieved by any particular boiler or boilers.
Investigation of The Quality of Water Treated by Magnetic Fields
Abstract
Passing water through a magnetic field has been claimed to improve chemical, physical and bacteriological quality of water in many different applications. Although the treatment process has been used for decades, it still remains in the realms of pseudoscience. If the claims of treating water with magnets are true, the process offers improvements on many of our applications of water in today’s world. A large number of peer reviewed journal articles have reported contradictory claims about the treatment.. Some of the most beneficial claimed water applications from magnetically treated water include improvement in scale reduction in pipes and enhanced crop yields with reduced water usage. Today we are still unsure whether the technology works and those who do believe it works are still trying to understand the mechanisms of how it works. Many research papers are starting to develop similar theories behind the mechanism of the treatment. From previous studies, it has been determined that the most successful MTD’s are those with alternating poles. The majority of the experiments performed during this research were determined to have insufficient controls to produce conclusive results. The conclusions from this research were focused on designing improved experiments to provide more conclusive results. A theory was developed to explain the MTD’s mechanisms of scale reduction. While the experimental results were not conclusive, the results attained backed the theory. Magnetically treated water does not do all that it is claimed it does. However, some of the positive results obtained during this research suggest that the improved experiments developed from this research may provide conclusive results on this controversial topic.
Investigation of The Quality of Water Treated by Magnetic Fields
Abstract
Passing water through a magnetic field has been claimed to improve chemical, physical and bacteriological quality of water in many different applications. Although the treatment process has been used for decades, it still remains in the realms of pseudoscience. If the claims of treating water with magnets are true, the process offers improvements on many of our applications of water in today’s world. A large number of peer reviewed journal articles have reported contradictory claims about the treatment.. Some of the most beneficial claimed water applications from magnetically treated water include improvement in scale reduction in pipes and enhanced crop yields with reduced water usage. Today we are still unsure whether the technology works and those who do believe it works are still trying to understand the mechanisms of how it works. Many research papers are starting to develop similar theories behind the mechanism of the treatment. From previous studies, it has been determined that the most successful MTD’s are those with alternating poles. The majority of the experiments performed during this research were determined to have insufficient controls to produce conclusive results. The conclusions from this research were focused on designing improved experiments to provide more conclusive results. A theory was developed to explain the MTD’s mechanisms of scale reduction. While the experimental results were not conclusive, the results attained backed the theory. Magnetically treated water does not do all that it is claimed it does. However, some of the positive results obtained during this research suggest that the improved experiments developed from this research may provide conclusive results on this controversial topic.
Water Treatment and Pathogen Control
This document is part of a series of expert reviews on different aspects of microbial water quality and health, developed by the World Health Organization (WHO) to inform development of guidelines for drinking-water quality, and to help countries and suppliers to develop and implement effective water safety plans. Contamination of drinking-water by microbial pathogens can cause disease outbreaks and contribute to background rates of disease. There are many treatment options for eliminating pathogens from drinking-water. Finding the right solution for a particular supply involves choosing from a range of processes. This document is a critical review of some of the literature on removal and inactivation of pathogenic microbes in water. The aim is to provide water quality specialists and design engineers with guidance on selecting appropriate treatment processes, to ensure the production of high quality drinking-water. Specifically, the document provides information on choosing appropriate treatment in relation to raw water quality, estimating pathogen concentrations in drinking-water, assessing the ability of treatment processes to achieve health-based water safety targets and identifying control measures in process operation.
Water Treatment and Pathogen Control
This document is part of a series of expert reviews on different aspects of microbial water quality and health, developed by the World Health Organization (WHO) to inform development of guidelines for drinking-water quality, and to help countries and suppliers to develop and implement effective water safety plans. Contamination of drinking-water by microbial pathogens can cause disease outbreaks and contribute to background rates of disease. There are many treatment options for eliminating pathogens from drinking-water. Finding the right solution for a particular supply involves choosing from a range of processes. This document is a critical review of some of the literature on removal and inactivation of pathogenic microbes in water. The aim is to provide water quality specialists and design engineers with guidance on selecting appropriate treatment processes, to ensure the production of high quality drinking-water. Specifically, the document provides information on choosing appropriate treatment in relation to raw water quality, estimating pathogen concentrations in drinking-water, assessing the ability of treatment processes to achieve health-based water safety targets and identifying control measures in process operation.
Analysis of Wastewater for Use in Agriculture – A Laboratory Manual of Parasitological and Bacteriological Techniques
Introduction:
The use of wastewater for crop irrigation is becoming increasingly common, especially in arid and semi-arid areas. Crop yields are higher as the wastewater contains not only water for crop growth, but also plant nutrients (mainly nitrogen and phosphorus). However, there is the risk that wastewater irrigation may facilitate the transmission of excreta-related diseases. In the late 1980s, the World Health Organization, the World Bank and the International Reference Centre for Waste Disposal sponsored a series of studies and meetings of experts to examine these health risks (International Reference Centre for Waste Disposal, 1985; Shuval et al., 1986; Prost, 1988; World Health Organization, 1989). From an appraisal of the available epidemiological evidence, it was established that the major risks were: the transmission of intestinal nematode infections both to those working in the waste-water irrigated fields and to those consuming vegetables grown in the fields; these infections are due to Ascaris lumbricoides (the human roundworm), Trichuris trichiura (the human whipworm), and Ancylostoma duodenale and Necator americanus (the human hookworms); and- the transmission of faecal bacterial diseases - bacterial diarrhoea and dysentery, typhoid and cholera - to the crop consumers.
Analysis of Wastewater for Use in Agriculture – A Laboratory Manual of Parasitological and Bacteriological Techniques
Introduction:
The use of wastewater for crop irrigation is becoming increasingly common, especially in arid and semi-arid areas. Crop yields are higher as the wastewater contains not only water for crop growth, but also plant nutrients (mainly nitrogen and phosphorus). However, there is the risk that wastewater irrigation may facilitate the transmission of excreta-related diseases. In the late 1980s, the World Health Organization, the World Bank and the International Reference Centre for Waste Disposal sponsored a series of studies and meetings of experts to examine these health risks (International Reference Centre for Waste Disposal, 1985; Shuval et al., 1986; Prost, 1988; World Health Organization, 1989). From an appraisal of the available epidemiological evidence, it was established that the major risks were: the transmission of intestinal nematode infections both to those working in the waste-water irrigated fields and to those consuming vegetables grown in the fields; these infections are due to Ascaris lumbricoides (the human roundworm), Trichuris trichiura (the human whipworm), and Ancylostoma duodenale and Necator americanus (the human hookworms); and- the transmission of faecal bacterial diseases - bacterial diarrhoea and dysentery, typhoid and cholera - to the crop consumers.
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