Mystery of Ageing of „Zero-Valent Iron“ (ZVI)

So called „zero-valent iron“, (ZVI), is used for water treatment, or, more generally for\nenvironmental remediation. In fact, the surface of the metallic iron powder in the presence of\nwater and oxygen cannot be considered as pure Fe0 but as a mixture of its corrosion products.\nThe remediation process occurs on the surface of these iron particles, hence, the degree of\n„corrosion“ is crucial for the process itself. Therefore, investigation of „aging“ of ZVI is an\nimportant prerequisite for deeper understanding of its activity.\nIn this work, the first results of the systematic study of aging of iron metal powder are\npresented. The investigation was performed in batch conditions in aqueous buffered solutions\npH 4, 4.7, 5.5 and in the presence of air oxygen. Increasing and then decreasing concentration\nof the Fe2+ ion in the solution appeared to be the important marker of aging process.\nIn the second part of the work, removal of Zn2+ ions using ZVI was investigated.\nElectrochemical techniques, namely polarography and its differential pulse form (DPP) were\nused for permanent monitoring of the presence of Fe2+ and Zn2+ ions in the studied solution.\nChanging concentrations of both ions revealed that at pH 5.5 the optimum aging time of ZVI\nfor removal of Zn2+ from aqueous solution is 6 hours

Distribution of the Giardia sp cysts in the Mfondi water basin (Cameroon): influence of some physico-chemical factors of the medium

No Abstract. Journal of the Cameroon Academy of Sciences Vol. 5(2&3) 2005: 85-9

Multicenter Study of Street Foods in 13 Towns on Four Continents by the Food and Environmental Hygiene Study Group of the International Network of Pasteur and Associated Institutes

Archives de Journal of Food Protection (https://jfoodprotection.org/toc/food/65/1)International audienceAn international multicenter study of ready-to-eat foods, sandwiches, and ice creams or sorbets sold in the streets and their vendors was carried out to assess the microbiological quality of these foods and to identify characteristics of the vendors possibly associated with pathogens. Thirteen towns in Africa, America, Asia, and Oceania were involved in the study. A single protocol was used in all 13 centers: representative sampling was by random selection of vendors and a sample of foods bought from each of these vendors at a time and date selected at random. Microbiological analyses were carried out using standardized Association Française de Normalisation methods, and the use of a standardized questionnaire to collect data concerning the characteristics of the vendors. Fifteen surveys were carried out, with 3,003 food samples from 1,268 vendors. The proportion of unsatisfactory food samples was between 12.7 and 82.9% for ice creams and sorbets and between 11.3 and 92% for sandwiches. For ice creams and sorbets, the sale of a large number of units (>80 per day) increased the risk of unsatisfactory food by a factor of 2.8 (95% confidence interval [CI]: 1.5 to 5.1), lack of training in food hygiene by 6.6 (95% CI: 1.1 to 50). and by a factor of 2.8 (95% CI: 1.4 to 5.4) for mobile vendors. These risk factors were not identified for sandwiches, this difference may be due to the presence of a cooking step in their preparation. These results show that the poor microbiological quality of these street foods constitutes a potential hazard to public health, that the extent of this hazard varies between the cities studied, and that vendors' health education in food safety is a crucial factor in the prevention of foodborne infections