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971.
The second and third steps of wastewater treatment in the tanning industry generate sludges that are rich in salts, organic matter and suspended solids. Since these are formally catalogued as industrial wastes by environmental legislation, they cannot be disposed of directly but need a final treatment. One of the problems with these wastes is their high water content, which has to be reduced. In the particular case of the concentrated streams from the secondary and tertiary treatment steps, the sludges are first concentrated by evaporation, and the evaporated water is used in other parts of the plant. This study, which preceded evaporator design, analysed the evaporation process (laboratory scale) of a saline residue produced in the reverse osmosis step of the treatment of tanning wastewaters by the company Aquagest Levante, S.A. in Lorca (Murcia, Spain), to ascertain its behaviour in the evaporation process and the evolution of its physical properties. The study served to determine the exact mineralogy and ionic composition as well as the characteristics of the waste in question. This information was used in the last step of the design of the evaporation equipment. 相似文献
972.
A Barba S Navarro M A Cámara 《Journal of environmental science and health. Part. B》1988,23(4):331-341
The Survan (a mixture of the insecticides chlorfenvinphos and cypermethrin) persistence in lemon citrus fruits, verna variety, is studied. In all the cases, residues of both compounds have been detected in the juices of the fruits treated. When the mixture of the insecticides is used at a concentration of 0.20%, the levels of chlorfenvinphos after 14 days is not higher than 0.14 ppm; however, when it is used at a 0.15% concentration, this value is overpassed in all the samples. The residues of the cypermethrin component are not higher than 0.35 ppm throughout the whole experiment. 相似文献
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A Fernández-Casalderrey M D Ferrando E Andreu-Moliner 《Journal of environmental science and health. Part. B》1992,27(2):155-164
The acute toxicity of endosulfan and diazinon to the freshwater rotifer Brachionus calyciflorus was determined after 24 hours exposure to these toxicants. The mean 24 hr-LC50 values were 5.15 and 29.22 mg/L for endosulfan and diazinon respectively. Based on these results, four sublethal concentrations were chosen to determined the median lethal time (LT50) at each concentration of toxicant tested. We also used a control with the solvent (acetone). The concentration tested were 1/5, 1/4, 1/2 and 2/3th LC50 (24hr) for both pesticides. We found a decrease in the median lethal time (LT50) with increasing pesticide concentrations. The LT50 values ranged from 6.49 to 3.48 days after endosulfan treatment, and from 6.96 to 2.49 days after diazinon exposure. No effects on survival were observed in control animals exposed to the solvent. 相似文献
975.
Maroušek Josef Maroušková Anna Zoubek Tomáš Bartoš Petr 《Environment, Development and Sustainability》2022,24(4):4835-4844
Environment, Development and Sustainability - The most common drinking water clarification technology worldwide is based on precipitation using the floccules of iron(III) oxide-hydroxide FeO(OH).... 相似文献
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