Consider a simple product. Consider an article of clothing that almost all have worn daily during a portion of their lives-a product considered an "essential" piece of wear. Consider the evolution of this product based on its use and the properties needed for it to stand up against daily abuse. This article attempts to illustrate how several polymers have been incorporated into the design of this product in order to take advantage of their various properties. No one of them has all the needed properties; but several, used together, provide a combination of materials with properties that provide a much needed product-the disposable diaper.The product-the baby diaper. Originally a piece of simple cotton cloth or other absorbent material, pinned at the sides. Later in its evolution the cotton material was covered
It has become increasingly clear in the last few years that the vast majority of municipal solid waste landfills produce leachate that contains elevated levels of tritium. The authors recently conducted a study of landfills in New York and New Jersey and found that the mean concentration of tritium in ten municipal solid waste landfills was 33,800 pCi/L with a peak value of 192,000 pCi/L. A 2003 study in California reported a mean tritium concentration of 99,000 pCi/L with a peak value of 304,000 pCi/L. Studies in Pennsylvania and the UK produced similar results. The USEPA MCL for tritium is 20,000 pCi/L. Tritium is also manifesting itself in landfill gas and landfill gas condensate. Landfill gas condensate samples from landfills in the UK and California were found to have tritium concentrations as high as 54,400 and 513,000 pCi/L, respectively. The tritium found in MSW leachate is believed to derive principally from gaseous tritium lighting devices used in some emergency exit signs, compasses, watches, and even novelty items, such as "glow stick" key chains.This study reports the findings of recent surveys of leachate from a number of municipal solid waste landfills, both open and closed, from throughout the United States and Europe. The study evaluates the human health and ecological risks posed by elevated tritium levels in municipal solid waste leachate and landfill gas and the implications to their safe management. We also assess the potential risks posed to solid waste management facility workers exposed to tritiumcontaining waste materials in transfer stations and other solid waste management facilities. KEYWORDSTritium, municipal solid waste leachate and gas, radioactivity
Over the last five years, the authors have been involved with treatability testing, process modeling and design of state-of-the-art treatment systems for removal of pharmaceutical actives and other microconstituents. The majority of the work was done on pharmaceutical and chemical wastewater. Municipal wastewater work will also be discussed. This paper presents a summary of work performed from the laboratory bench scale testing to pilot testing to design and full scale operations data. Cost and economics will be presented for the following technologies: • Biological Treatment • Advanced Oxidation Processes (AOP) using Ozone and UV/Hydrogen Peroxide • Ultrasound • Ultrafiltration and Reverse Osmosis • Carbon AdsorptionIndustries and municipalities are faced with many technology choices today for organics and nutrient removal. Microconstituents including active pharmaceutical ingredients (APIs) are becoming a concern and are being evaluated by EPA for future regulations. EPA has already issued Draft Water Quality Criteria for nonylphenol. Some industries, such as pharmaceutical, have been proactive and are already implementing treatment to control microconstituents entering the environment. Municipalities are studying the removal of microconstituents through treatment processes including what is contained in biosolids for land application and composting. There are numerous activated sludge process configurations being used today including: conventional activated sludge (both plug flow and completely mixed), fixed film and membrane systems, and sequencing batch reactors (SBRs) to name a few.Dynamic modeling of wastewater treatment plants (WWTPs) also a trend that offers valuable insights into plant operations, trouble-shooting, optimizing plant process operations, and training plant staff. The application of the currently published activated sludge models (i.e., BIOWIN and GPSX) to the modeling of plants treating domestic wastewater has been well documented. Conversely, the application of these models to the simulation of facilities treating industrial wastewaters has been less common. The simulation of industrial activated sludge plants poses special challenges due to the unique and highly variable nature of the wastewater and the extreme operating conditions often encountered. This paper will discuss the special challenges associated with modeling industrial and municipal WWTPs, highlight the model enhancements often required to handle microconstituents including APIs, provide examples of pilot-testing, scale-up, design, lessons learned, modeling and outline future modeling trends including: WEFTEC 2011Tracking the dynamic fate of specific trace organic compounds (including metabolite formation and removal;• Modeling the effect of inhibitory levels of substances on biological competence, contaminant fate and biomass settling characteristics; and • On-line modeling with potential to include warnings of imminent upsets and knowledge-based solutions.Modeling tools such as BIOWIN, GPSX, Water 9 and TOXCHEM are utilize...
Batch and continuous flow treatability tests have been used for years to develop process design criteria for industrial and municipal wastewater treatment plant design. The continuous flow tests are performed to simulate the actual or projected COD and BOD loading rates and sludge ages and determine the expected effluent quality. These tests are typically performed at a minimum of 3 sludge ages after an initial sludge acclimation period or typically a period of 2 to 3 months to obtain performance data at steady state conditions. These tests can be performed in the laboratory at the bench-scale or as a pilot study at the plant. The pilot study has the advantages of developing performance data on day to day influent wastewater variability thereby providing more representation of a full-scale plant. Batch tests which require much less time and cost are done by adding wastewater to an acclimated biological sludge for a period of 1 to 2 days. Batch studies have traditionally been used to characterize the biodegradability of a waste and develop COD and ammonia removal kinetic rate constants. The batch tests are relatively quick and inexpensive tests to perform compared to continuous flow tests in the laboratory and pilot tests in the field. This paper describes a technique that can be used in analyzing the less costly batch study data to develop treatment plant design criteria without the need for additional testing. A methodology is presented to conduct the batch tests and then develop continuous test K rate. The benefit of this approach is that it can save significant time and expense on a design project for an activated sludge treatment process. The K rate developed can be used to design completely mixed activated sludge processes including membrane bioreactors. A real case study is presented to show the difference in design for a pharmaceutical wastewater treatment nitrification system using batch test data versus continuous flow test data.
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