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The cyanobacterium
Keywords: chloramination, CT, microcystin,
Comparison of
Cyanobacteria are able to produce several metabolites that have toxic effects on humans and animals. Among these cyanotoxins, the hepatotoxic microcystins (MC) occur frequently. The intracellular MC content produced by two strains of Microcystis aeruginosa, PCC7806 and PCC7820, and its production kinetics during the culture time were studied in order to elucidate the conditions that favour the growth and proliferation of these toxic strains. Intracellular MC concentrations measured by liquid chromatography (LC)...
Vulnerability of Quebec drinking-water treatment plants to cyanotoxins in a climate change context
Cyanobacteria are a growing concern in the province of Quebec due to recent highly publicised bloom episodes. The health risk associated with the consumption of drinking water coming from contaminated sources was unknown. A study was undertaken to evaluate treatment plants' capacity to treat cyanotoxins below the maximum recommended concentrations of 1.5 μg/L microcystin-LR (MC-LR) and the provisional concentration of 3.7 μg/L anatoxin-a, respectively. The results showed that close to 80% of the water treatment...
Influence of phosphorus on Microcystis growth and the changes of other environmental factors
The growth processes of Microcystis aeruginosa (FACHB-41) in simulated Taihu Lake water with different phosphorus concentrations were investigated using laboratory microcosms. The algal biomass increased with the increase of phosphorus concentration when it was lower than 0.445 mg/L, while the dissolved oxygen (DO) and pH increased, dissolved inorganic nitrogen (DIN) and light intensity underwater(I) decreased. Responding to the changes of the `environmental factors`, the cellular carbohydrate and its ratio to...
Algal Treatments
Global warming means algal blooms can only increase. Tom Hall of the WRc Group reports on the latest research into treatment programmesExcessive algal growth in raw water reservoirs can cause severe problems with water supply, even in a traditional UK climate. Global warming means algal problems could become more frequent and acute in the UK, so effective control measures will become more important. This issue has been the subject of recent research by WRc through Toxic, a European programme supported by UKWIR.The...
Minnesota Dairy Runs Hydrogen Fuel Cell on Biogas
Untitled Document Demonstration project with university researchers involves cleaning biogas to develop renewable energy options for farmers. A MINNESOTA dairy - the Haubenschild family farm near Princeton - is making history by becoming the first demonstration project in the world to run a hydrogen fuel cell from the biogas captured from cows. For five years, as reported in BioCycle, the Haubenschilds have been operating an anaerobic digester to process manure from their cows (now numbering...
Artificial mixing to reduce growth of the blue-green alga Microcystis in Lake Nieuwe Meer, ...
The problem of Lake Nieuwe Meer (area = 1.3 km2, max. depth 30 m, Ptot = 500 mg/m3) was extensive growth of Microcystis with disturbing scum forming. Since 1993 the lake has been artificially mixed in summer by a bubble plume installation. The result is quite successful since the mass of Microcystis is up to 20 times lower than in the years before mixing and no scum is present any more. The study in Lake Nieuwe Meer showed a shift from cyanobacterial dominance (mainly Microcystis) to flagellates, green-algae and...
Evaluation of Ecological Risks Associated with the use of Chlorine Dioxide for the Bleaching of ...
1.1 Scope and Objectives A small number of viable options are presently available for the bleaching of wood pulp (delignification and brightening) during the manufacture of pulp and paper. The use of chlorine dioxide (ClO2) in the bleaching process has largely superceded the earlier use of Cl2, or elemental chlorine, in the majority of North American pulp mills: It was discovered over a decade ago that the previous widespread use of Cl2 contributed to the production and subsequent release to the environment of...
Chloramines
OVERVIEW When chlorine is added to a water supply containing certain organics, the formation of halogenated organics occurs. Called `trihalogenated methanes` (THM`s) these reaction products are suspected carcinogens and maximum allowable limits in municipal supplies are imposed by the U.S. Environmental Protection Agency (EPA). To reduce the potential for the formation of THM`s, many U.S. municipal supplies are converting their chlorine (Cl2) disinfection method to chloramine addition. Chloramines have a low...
Elemental Chlorine-Free (ECF): Pollution Prevention for the Pulp and Paper Industry
Imagine being in charge of a chemical company. One day a fire breaks out, and an employee, designated as a first responder, is killed fighting the blaze. Then OSHA investigators discover that the man died primarily because both his training and his equipment were inadequate. This scenario is why CPL 2-2.59A should put anyone who runs a HAZMAT facility into a state of introspection. These employers need to ask themselves: `When was the last time that our Emergency Response Plan was brought up to date? Do our...
Compilation of EU Dioxin Exposure and Health Data
Introduction There is considerable public, scientific and regulatory concern over the possible adverse health effects of chronic exposure to trace levels of persistent organic pollutants. The class of compounds made up of the polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF), often collectively known as dioxins, has received widespread attention and attracted a great deal of research, following the accidental release of the most toxic of these (2,3,7,8 TCDD) at Seveso in 1976. Diox...
Performance-Based Measurement Systems
Many of the Environmental Protection Agency`s (EPA`s) methods used to monitor air, water and soil for environmental contaminants prescribe step-by-step details on how the chemical analysis must be conducted and prohibit any deviations or variations. The EPA has recognized that monitoring equipment and technology have improved tremendously over the last few years; that environmental media do not always act the same way for each analysis; and that the matrix may affect the analysis and results. The EPA has been...
Properties and Behavior of Nonhalogenated VOC`s
An important consideration when evaluating a remedy is whether the compound is nonhalogenated or halogenated. A nonhalogenated compound is one which does not have a halogen (e.g., fluorine, chlorine, bromine, or iodine) attached to it. The vendor of the technology being evaluated must be informed whether the compounds to be treated are nonhalogenated or halogenated. In most instances, the vendor needs to know the specific compounds involved so that modifications to technology designs can be made, where appropriate...
Air Sparging - Technology Overview
Air sparging involves injecting a gas (usually air/oxygen) under pressure into the saturated zone to volatilize groundwater contaminants and to promote biodegradation in saturated and unsaturated soils by increasing subsurface oxygen concentrations. Vola tilized vapors migrate into the vadose zone where they are extracted via vacuum, generally by a soil vapor extraction system. The term biosparging is sometimes used interchangeably with air sparging to highlight the bioremediation aspect of the treatment process...
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