DOMESTIC AND INDUSTRIAL WASTES ARE TREATED FOR TWO DISTINCT PURPOSES: (1) separation of water from the putrescible organic material, dissolved and particulates; (2) disinfection of the water to prevent the transmission of water-borne pathogens.Currently, in North America, disinfection is accomplished by the addition of a powerful oxidizing chemical such as chlorine or a related compound.Separation of solids from liquid is achieved by flocculation followed by sedimentation. Flocculation may be biologically or chemically induced, the former being more economical where practical. Methods of bioflocculation described include the following processes: (1) activated sludge, (2) contact stabilization, (3) tapered aeration, (4) step aeration, (5) total oxidation, and (6) trickling filter.Non-mechanical processes of sewage treatment are economically and technically sound in many rural and semi-rural applications. The oxidation pond ((lagoon) is not mechanical, but this consideration must not lead rural municipalities to a program of neglect. All plants treating human wastes should provide a disinfection process at the effluent. (+info)
Sanitary engineering aspects of nuclear energy developments.
(10/79)
So many developments have taken place in the field of nuclear energy since 1956, when the author's previous paper on radioactive waste disposal was published in the Bulletin of the World Health Organization, that a fresh review of the subject is now appropriate.The present paper deals with those aspects of the problem which are of most interest to the sanitary engineer. It considers specific points in the latest recommendations of the International Commission on Radiological Protection in relation to public drinking-water supplies, and examines the problem of fall-out, with special reference to the presence and significance of strontium-90 in drinking-water. A general survey of the various uses of radioactive materials is followed by a discussion of the legislative and control measures necessary to ensure safe disposal of wastes. The methods of waste disposal adopted in a number of nuclear energy establishments are described in detail. The paper concludes with some remarks on solid waste disposal, siting of nuclear energy industries and area monitoring. (+info)
Mycobacteria in water and loose deposits of drinking water distribution systems in Finland.
(11/79)
Drinking water distribution systems were analyzed for viable counts of mycobacteria by sampling water from waterworks and in different parts of the systems. In addition, loose deposits collected during mechanical cleaning of the main pipelines were similarly analyzed. The study covered 16 systems at eight localities in Finland. In an experimental study, mycobacterial colonization of biofilms on polyvinyl chloride tubes in a system was studied. The isolation frequency of mycobacteria increased from 35% at the waterworks to 80% in the system, and the number of mycobacteria in the positive samples increased from 15 to 140 CFU/liter, respectively. Mycobacteria were isolated from all 11 deposits with an accumulation time of tens of years and from all 4 deposits which had accumulated during a 1-year follow-up time. The numbers of mycobacteria were high in both old and young deposits (medians, 1.8 x 10(5) and 3.9 x 10(5) CFU/g [dry weight], respectively). Both water and deposit samples yielded the highest numbers of mycobacteria in the systems using surface water and applying ozonation as an intermediate treatment or posttreatment. The number and growth of mycobacteria in system waters correlated strongly with the concentration of assimilable organic carbon in the water leaving the waterworks. The densities of mycobacteria in the developing biofilms were highest at the distal sites of the systems. Over 90% of the mycobacteria isolated from water and deposits belonged to Mycobacterium lentiflavum, M. tusciae, M. gordonae, and a previously unclassified group of mycobacteria. Our results indicate that drinking water systems may be a source for recently discovered new mycobacterial species. (+info)
Microbiological investigations on a nosocomial case of Legionella pneumophila pneumonia associated with water birth and review of neonatal cases.
(12/79)
A case of Legionella pneumophila 1 pneumonia, confirmed by positive serology and urinary antigen, occurred in a 7-day old neonate after water birth in hospital. As respiratory samples were not available for culture, further microbiological investigations were performed in neonate and environment, in order to recognize the source of infection. The hospital water supply was contaminated by L. pneumophila 1 strains (300-2000 cfu/L) of two monoclonal subtypes of Pontiac subgroup. L. spiritensis (10-225 cfu/L) was isolated from cold tap water of the patient's home. PCR from tap and humidifiers water of the patient's home was positive for Legionella spp, but not for L. pneumophila. Because L. pneumophila 1, responsible of child infection, was only isolated from the hospital pool water for waterbirthing, we conclude that the infant acquired the nosocomial legionellosis by prolonged delivery in contaminated water, perhaps by aspiration. Infection control measures for waterbirthing are highly recommended. A review of neonatal case of legionellosis is also presented. As this rare infection may have a high fatality rate if unrecognized, pediatricians should be aware of the possibility of the legionellosis in newborns. (+info)
Constructing and dismantling frameworks of disease etiology: the rise and fall of sewer gas in America, 1870-1910.
(13/79)
For roughly forty years, from 1870 to 1910, Americans recognized and feared gases emanating from sewers, believing that they were responsible for causing an array of diseases. Fears of sewer gas arose from deeper anxieties toward contact with decomposing organic matter and the vapors emitted from such refuse. These anxieties were exacerbated by the construction of sewers across the country during the mid-to-late-nineteenth century, which concentrated waste emanations and connected homes to one another. The result was the birth of sewer gas and the attribution of sickness and death to it, as well as the development of a host of plumbing devices and, especially, bathroom fixtures, to combat sewer gas. The rise of the germ theory, laboratory science, and belief in disease specificity, however, transformed the threat of sewer gas, eventually replacing it (and the larger fear of miasmas) with the threat of germs. The germ theory framework, by 1910, proved more suitable than the sewer gas framework in explaining disease causation; it is this suitability that often shapes the relationship between science and society. (+info)
Reducing lead exposure from drinking water: recent history and current status.
(14/79)
This article discusses the issue of lead contamination of drinking water, noting the various regulatory-driven measures that have been adopted in the U.S. since 1986 to address this public health issue. The article summarizes the literature on the dynamics of tap water lead contamination and discusses this widespread source of lead exposure in the context of the latest research evidence. (+info)
Related factors to human toxocariasis in a rural community of Argentina.
(15/79)
The objective of this study was to evaluate the relationship between toxocariasis frequency and demographic, environmental, sanitary variables, eosinophylia, and other intestinal parasites in a rural population of Argentina. Serological examination of 100 individuals was carried out by using ELISA technique for the detection of anti-toxocara antibodies. Eosinophiles in peripheral blood, presence of intestinal parasites, and demographic, environmental, and socio-cultural data were evaluated. Eighty-one feces samples of dogs belonging to the studied people were analyzed to detect eggs of Toxocara canis. Thirty of them were from 30 dogs and 51 were pools from dog feces. Samples of dirt from around the homes (n: 47) and from public park (n: 4) were taken. To determine the associations, the c(2) and Fisher tests were used. The seroprevalence was 23%. Eosinophilia in peripheral blood was detected in 86.95% seropositive individuals and in 37.66% seronegative individuals (p < 0.001, OR = 11.03). Of the 23 people with positive serology, 69.56% had at least one intestinal parasite. All individuals with positive serology had dogs in their homes. Among the dog owners there was a significant association between the presence of anti-toxocara antibodies and home flooding. Eggs of T. canis were detected in the feces of 5/81 dogs and three of these dogs belonged to individuals with positive serology. Eggs of Toxocara spp. were found in 41.17% of the dirt samples, eight of which came from the area surrounding the homes of individuals with positive serology (p = 0.032; OR = 4.36). Taking into account all the variables influencing the frequency of toxocariasis in this population, the implementation of Public Health programs specifically focused on anti-parasitic treatment of dogs is recommended. (+info)
New insight into solvent-related end-stage renal disease: occupations, products and types of solvents at risk.
(16/79)
OBJECTIVES: It has been shown that all-solvent exposure is associated with the progression of primary glomerulonephritis to end-stage renal disease (ESRD), but little is known about the type of solvents that are high risk. The aim of this study was to investigate the role of solvents by occupation, product and type. METHODS: Using a retrospective cohort design, the authors studied 269 patients with non-end-stage and biopsy-proven primary glomerulonephritis diagnosed between 1994 and 2001 in Paris and its suburbs. Two industrial hygienists evaluated patients' exposures from lifetime occupational histories collected by interview from 2002-4, and using a list of the 30 most common solvents. The studied outcome was ESRD, defined as glomerular filtration rate <15 ml/mn/1.73 m(2) or dialysis. It was recorded during a mean follow-up of five years. Cox models were used to estimate adjusted hazard ratios (HR) of ESRD related to exposures. RESULTS: Eighteen per cent of the patients had ever been exposed to solvents. Those with the highest risk of progression to ESRD were exposed machinery fitters and machine assemblers (HR 4.7, 95% CI 1.2 to 17.4) and plumbers/welders (HR 4.2, 95% CI 1.3 to 13.6), as compared to never exposed patients, as well as those who ever handled printing inks and petroleum products (HR 12.6 (95% CI 1.7 to 94.9) and 3.2 (95% CI 1.4 to 7.2), respectively). Among solvents, the highest risks were found for: toluene/xylene (HR 5.1, 95% CI 1.8 to 14.8), gasoline, fuel and gas-oil (HR 8.6, 95% CI 2.7 to 27.4), and ketones (HR 13.3, 95% CI 1.4 to 123.5). CONCLUSION: This study highlights the potential nephrotoxicity of several solvents. Intervention to promote screening for proteinuria in exposed workers may prevent the progression of glomerulonephritis to ESRD. (+info)