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At least 631 records · Page 35Linked to original sources
PubMed1976

Drinking water for the future.

The Safe Drinking Water Act of 1974 represents an important step in improving the quality of public water supply in the United States. However, it fails to address two important problems: (1) The 1970 Public Health Service Community Water Supply Survey revealed that small public water supply systems often deliver poor quality water. The Act does not assure that these supplies will now receive appropriate attention; furthermore, the Act does not address the needs of the 50 million people not now served by public water systems; (2) About one-third of our population draws its drinking waters from polluted sources. The decisions to use these low cost sources were made generations ago when consumers could be protected from water-borne infectious disease. A new problem has now arisen--the presence of numerous synthetic organic chemicals of uncertain health consequence, not removed by conventional water treatment. The Act does not address this problem. Regionalization and the integration of water resource and water pollution control authorities are proposed as a reasonable solution to these problems. The development of dual water supply systems in order to conserve scarce pure water sources for human consumption appears to be a feasible way to avoid using polluted waters for drinking. The development of dual supplies would be enhanced by regionalization and integration of water authorities.

Environmental Health↗
PubMed1978

Aquatic vegetation and water pollution control: public health implications.

Results obtained from pilot studies and the operation of a plant scale treatment facility located at the Williamson Creek Wastewater Treatment Plant at Austin, Texas, demonstrate that culture of the water hyacinth Eichhornia crassipes in shallow earthen basins is effective in the removal of algae, fecal coliform bacteria dn deleterious impurities from wastewater stabilization pond effluent. Stabilization ponds followed by hyacinth culture constitute an economical, low energy treatment system which reduces significantly those potential health hazards associated with wastewaters. Harvested hyacinths represent a useful product which could be converted into compost, or used directly as a soil amendment.

Marine Biology↗
PubMed1985

Industrial wastes and public health: some historical notes, Part I, 1876-1932.

This article has focused on the relatively low priority accorded industrial wastes compared to human wastes by the public health community in the period from 1876 through 1932. The critical reason for this prioritization was the potential for acute health effects from human wastes as compared with the belief that industrial wastes had only indirect effects. State departments of health normally only responded to industrial wastes when they endangered the potable nature of water supplies or interfered with water and sewage treatment processes. Within the public health community, however, a relatively small group of interdisciplinary professionals argued for attention to the indirect health effects of industrial wastes and their impacts on the total stream environment. In conjunction with other groups interested in clean streams--such as sportsmen and manufacturers who required high quality process water--they pushed for a broader state legislative mandate in regard to pollution control. Some states created new bureaus or boards with responsibility for industrial wastes and the larger stream environment but the attack on industrial pollution remained limited in this period. The final significant development regarding industrial pollution and public health concerned the formulation by Streeter-Phelps of the Public Health Service of a theory of stream purification with a set of general quantitative indicators. This application was of particular importance in regard to the high-oxygen consuming nature of organic industrial wastes and the wide variety of effluents that existed. Industrial wastes constituted what Harvey Brooks, in his essay "Science Indicators and Science Priorities" calls a very "messy" research problem--one that does "not lend itself to elegant and widely applicable generalizations."(ABSTRACT TRUNCATED AT 250 WORDS)

History, 19th Century↗
PubMed2001

Urban history, urban health.

Over the course of the 20th century, the United States became an urban nation: 80% of Americans now live in metropolitan areas. Supplying basic sanitary services-drinking water, sewers, and garbage removal-to these cities is a gargantuan task, yet most people have little understanding of urban infrastructure systems and their enormous regional ecologic impacts. Municipalization of sanitary services, especially since 1880, distanced people from their wastes and gave city dwellers a simplistic experience of one-way material flow through cities, without knowledge of the environmental costs. Most sanitary infrastructures were built primarily for durability and lack the elasticity to meet changing needs. The challenge now is to adapt sanitary systems for flexibility and simultaneously move from unchecked material consumption toward resource-based thinking.

Conservation of Natural Resources↗
PubMed2006

Efficient design and operation of a data acquisition system for pressurized pipeline systems.

The unsteady flow analysis of pipeline systems provides useful guidelines for implementing data acquisition components such as data filtering ranges, sensor locations and sampling frequencies. A theoretical integration among hydraulics, free vibration analysis and signal processing is proposed for a comprehensive approach aiming at enhanced design and operation of data acquisition system. Transient analysis is performed to extract flow variation by a valve modulation in a pipeline system. Frequency transformation analysis is developed to convert pressure variations between time domain and frequency domain. Free vibration analysis provides spatial distribution of impedance characteristics and pressure variation for determining optimum sensor location. A real-time filter can be designed to secure valid signals of any particular unsteady event. Hypothetical and experimental applications show that the proposed method has potentials of the leakage detection of a pipeline system as well as an efficient design of data acquisition system.

Equipment Failure Analysis↗
PubMed2006

Failure monitoring in water distribution networks.

An algorithm for the burst detection and location in water distribution networks based on the continuous monitoring of the flow rate at the entry point of the network and the pressure at a number of points within the network is presented. The approach is designed for medium to large bursts with opening times in the order of a few minutes and is suitable for networks of relatively small size, such as district metered areas (DMAs). The burst-induced increase in the inlet flow rate is detected using the modified cumulative sum (CUSUM) change detection test. Based on parameters obtained from the CUSUM test, the burst is simulated at a number of burst candidate locations. The calculated changes in pressure at the pressure monitoring points are then compared to the measured values and the location resulting in the best fit is selected as the burst location. The EPANET steady-state hydraulic solver is utilised to simulate the flows and pressures in the network. A sensitivity-based sampling design procedure is introduced to find the optimal positions for pressure monitoring points. The proposed algorithm is tested on a case study example network and shows potential for burst detection and location in real water distribution systems.

Algorithms↗
PubMed2006

Mesophilic-thermophilic-mesophilic anaerobic digestion of liquid dairy cattle manure.

The potential of a mesophilic-thermophilic-mesophilic anaerobic digestion system was investigated with respect to improvement of both digestion and sanitation efficiencies during treatment of liquid cattle manure. The pilot plant produced a high methane yield from liquid dairy cattle manure of 0.24 m3 (kg VSfed)(-1) Considering the low system loading rate of 1.4-1.5 kg VS (m3 d)(-1), digestion efficiency compared to conventional processes did not appear improved. The minimum guaranteed retention time in the tubular thermophilic reactor was increased compared to a continuously stirred tank reactor. Levels of intestinal enterococci in raw liquid manure as determined with cultivation methods were reduced by 2.5 -3 log units to a level of around 10(2) cfu/mL. This sanitizing effect was achieved both during mesophilic-thermophilic-mesophilic and thermophilic-mesophilic treatment, provided the thermophilic digester was operated at 53-55 degrees C. A change in feeding interval from 1 h to 4 h did not significantly alter methane yield and sanitation efficiency. It was proposed that a two-stage, thermophilic-mesophilic anaerobic digestion system would be able to achieve the same sanitizing effect and equal or better digestion efficiency at lower costs.

Animals↗
PubMed2006

Sediment management in sustainable urban drainage system ponds.

Since removal and disposal of sustainable urban drainage system (SUDS) sediment can incur high maintenance costs, assessments of sediment volumes, quality and frequency of removal are required. Sediment depth and quality were surveyed annually from 1999-2003 in three ponds and one wetland in Dunfermline, Scotland, UK. Highest sediment accumulation occurred in Halbeath Pond, in the most developed watershed and with no surface water management train. From comparison of measured potentially toxic metal concentrations (Cd, Cr, Cu, Fe, Ni, Pb, Zn) with standards, the average sediment quality should not impair aquatic ecosystems. 72-84% of the metal flux into the SUDS was estimated to be associated with coarse sediment (> 500 microm diameter) suggesting that management of coarse sediment is particularly important at this site. The timing of sediment removal for these SUDS is expected to be determined by loss of storage volume, rather than by accumulation of contaminants. If sediment removal occurs when 25% of the SUDS storage volume has infilled, it would be required after 17 years in Halbeath Pond, but only after 98 years in Linburn Pond (which has upstream detention basins). From the quality measurements, sediment disposal should be acceptable on adjacent land within the boundaries of the SUDS studied.

Cities↗
PubMed2006

Assessment of WWTP design and upgrade options: balancing costs and risks of standards' exceedance.

Numerical models can be used to evaluate design and upgrade scenarios of urban wastewater systems on the basis of their ecological consequences. The objective of this paper is to illustrate a systematic procedure of system design/upgrade. This procedure consists of the following steps: (1) data collection and data reconstruction; (2) model building and calibration; (3) evaluation of scenarios; (4) uncertainty assessment. In contrast to conventional practice, this approach allows to choose the most appropriate trade-off between cost of measures and risk of non-compliance with regulatory limits. An example of its application dealing with the assessment of WWTP design and upgrade options is provided. Results show that by reducing the tank volumes compared to conventional design procedures, costs can be reduced sensibly while the risk of not meeting legislative requirements are only slightly increased.

Cities↗
PubMed2006

Bench- and pilot-scale sludge electrodewatering in a diaphragm filter press.

Electrodewatering is a technique in which pressure dewatering is combined with electrokinetic effects to realize an improved solid/liquid separation and hence increased filter cake dry matter contents. In order to be energy efficient, it is shown that sludge should be dewatered by pressure dewatering to a high extent prior to electric field application, and a sufficient contact time for the electric field must be guaranteed. In order to realize these goals, a bench- and pilot-scale diaphragm filter press suited for electrodewatering were constructed for treatment of sewage and other types of sludges. It was shown that electrodewatering of sludge is a feasible technique, especially for biological sludge types. Other types of sludge are less suited for electrodewatering because of the restricted improvements that can be realized in cake dry matter content and the high electric energy consumption. Furthermore, it was shown in pilot-scale tests that the use of a diaphragm filter press with electrodewatering facilities was very well suited to deliver dry filter cakes of sewage sludge at a moderate energy consumption. Depending on local market prices for investment, operating and sludge disposal costs, this technology may therefore lead to important savings in the sludge management process.

Electrochemistry↗
PubMed2006

Benchmarking of WWTP design by assessing costs, effluent quality and process variability.

Process choice and dimensioning of WWTPs is a particularly sensitive step to cost-efficiently comply with regulatory standards. This step accounts only for a small fraction of the upfront costs, but it can lead to substantial savings. This paper illustrates the results of a systematic methodology to evaluate system design/upgrade options. In contrast to conventional practice, this approach allows the choice between the most appropriate trade-off between cost of measures and effluent quality, and to assess the reliability of a process layout. It is therefore a flexible instrument to cope with the flexibility and complexity of integrated water management regulations. Results show good agreement of the simulations with extensiv benchmarking studies on actual plants. For that reason, the suggested methodology can provide valuable support also to such practices.

Benchmarking↗
PubMed2006

Guilty! Successful homicide prosecution against company that killed two workers in Arizona.

Why should an employer who sends a worker to his death in an unmonitored confined space or an unprotected 12-foot deep trench not be prosecuted under a felony as opposed to the Occupational Safety and Health Act, where the maximum penalty for willfully killing a worker is a misdemeanor with a maximum of six months in jail? They should be so charged. The author deplores merely waiting for Congress to increase OSHA penalties.

Adult↗
PubMed1976

The recent history of parasitic disease in China: the case of schistosomiasis, some public health and economic aspects.

This paper examines the extent to which the prevalence of schistosomiasis may have increased during the period 1958-1964. Certain hypotheses are examined, mainly dealing with irrigation and water conservancy construction. The probable economic and demographic effects of schistosomiasis are also examined. The article concludes that schistosomiasis prevalence probably did increase, but that the economic-demographic effects of this were probably minimal.

Agriculture↗