ABSTRACT
The ability of reed beds to remove significant levels of metals from effluent streams is well cited in the literature. Various methods of removal have been postulated and demonstrated including physical methods such as filtration and settlement, precipitation when the metal is present as a salt and adsorption to organic species or take up by macrophytes when the metal is in a soluble or ionic form. Consequently, reed beds have been used in a variety of applications for metal removal in water treatment processes. The distillation process for whisky generates an effluent containing a significant amount of copper which is scoured from the copper stills during the process and cleaning operations. High soluble copper concentrations can breach discharge consents. A horizontal subsurface flow reed bed system has been designed and installed for copper removal at a distillery in Scotland. This paper presents the findings of the literature search, outlines the design of the bed and reviews the performance results.
Subject(s)
Copper/isolation & purification , Distillation/methods , Waste Disposal, Fluid/methods , Wetlands , Plant Development , Solutions , Thermodynamics , United KingdomABSTRACT
We describe a method for high-pressure freezing and rapid freeze-substitution of cells in tissue culture which provides excellent preservation of membrane detail with negligible ice segregation artefacts. Cells grown on sapphire discs were placed 'face to face' without removal of tissue culture medium and frozen without the protection of aluminium planchettes. This reduction in thermal load of the sample/holder combination resulted in freezing of cells without visible ice-crystal artefact. Freeze-substitution at -90 degrees C for 60 min in acetone containing 2% uranyl acetate, followed by warming to -50 degrees C and embedding in Lowicryl HM20 gave consistent and clear membrane detail even when imaged without section contrasting. Preliminary data indicates that the high intrinsic contrast of samples prepared in this way will be valuable for tomographic studies. Immunolabelling sensitivity of sections of samples prepared by this rapid substitution technique was poor; however, reducing the uranyl acetate concentration in the substitution medium to 0.2% resulted in improved labelling. Samples substituted in this lower concentration of uranyl acetate also gave good membrane detail when imaged after section contrasting.
Subject(s)
Freeze Substitution/methods , Animals , Cells, Cultured , Chlorocebus aethiops , Cricetinae , Freezing , Hydrostatic Pressure , Immunohistochemistry , Microscopy, Immunoelectron , Organometallic Compounds , Vero CellsABSTRACT
High-pressure freezing is applicable to both morphological and immunocytochemical studies. We are investigating the morphogenesis of foot-and-mouth disease virus and African swine fever virus by the use of high-pressure freezing of infected cells. Foot-and-mouth disease virus particles are not detected in sections of conventionally immersion-fixed infected cells, but when the cells are prepared by high-pressure freezing, newly formed virions are readily seen throughout the cell. We report two methods for high-pressure freezing of virally infected cells: first, two sapphire discs frozen 'face to face' with a narrow spacer to prevent cell damage and, second, a fibrous filter substrate that can be easily cut into discs to fit into the freezing planchettes. Cells readily adhere to the fibres in vitro, and the complete disc can be rapidly transferred to the planchettes for freezing. Immunolabelling studies of the microneme proteins of the parasite Eimeria tenella indicate that high-pressure freezing followed by freeze-substitution in acetone with uranyl acetate allows high-sensitivity immunolabelling for these proteins.
