Detection of Salmonella spp. and Listeria monocytogenes in suspended organic waste by nucleic acid extraction and PCR.
A nucleic acid-based method for the detection of the bacterial pathogens Salmonella spp. and Listeria monocytogenes in biological waste was developed. The detection limits were less than 10 cells per ml of biological waste. The method does not include a phenol extraction step and can be easily performed in 1 to 2 days. (+info
Evaluation of dehydrated restaurant food waste products as feedstuffs for finishing pigs.
Two dehydrated restaurant food waste (DFW) products were evaluated as potential feedstuffs for finishing pigs. For each product, fresh food wastes were obtained from food service operations at a resort complex in central Florida. The wastes were mostly leftover food and plate scrapings. The wastes were minced, blended with a feed stock (soy hulls and wheat flour [DFW1] or soy hulls and ground corn [DFW2]), pelleted, and dried. The dried product was then blended with additional minced fresh food wastes and dried; this process was then repeated. The final DFW products contained approximately 60% dried food wastes. The DFW1 and DFW2 products contained 11.4 and 8.4% moisture, 15.0 and 14.4% CP, 13.8 and 16.0% crude fat, 10.4 and 14.5% crude fiber, 5.8 and 4.7% ash, .63 and .64% lysine, .54 and .63% Ca, .34 and .38% P, .69 and .86% Cl, and .35 and .47% Na, respectively. Two feeding trials with 48 and 72 finishing pigs (56 to 112 kg), respectively, were conducted comparing diets without (control) or with the DFW product included at 40% of the diet (DFW1) for Trial 1 and 40 or 80% of the diet (DFW2) for Trial 2. Pigs fed the DFW diets in both trials had ADG that were similar (P > . 10) to and average gain:feed ratios that were superior (P = .06, Trial 1; P < .01; linear, Trial 2) to those for control pigs. Carcass lean content and lean quality scores were not reduced (P > . 10) by feeding pigs the DFW diets in either trial. Carcass fat became softer (P < .01; linear) with increasing amount of DFW2 in the diet in Trial 2. Thus, dehydrated restaurant food wastes have the potential to produce a nutritious feedstuff for pigs while offering a viable solid waste disposal option. (+info
Exposure to airborne microorganisms and volatile organic compounds in different types of waste handling.
Occupational exposure of workers to airborne microorganisms and volatile organic compounds (VOC) in different types of waste treatment situations was examined during summer time. Microorganisms were collected as stationary samples using a six-stage Andersen impactor, while for VOCs both personal and stationary sampling was conducted. The exposure at the waste handling facility was considerably greater than at landfill sites or in waste collection. The concentrations of viable fungi were maximally 10(5) cfu/m3, and the concentrations of both total culturable bacteria and Gram-negative bacteria exceeded the proposed occupational exposure limit values (OELV), being 10(4) and 10(3) cfu/m3, respectively. Exposure to VOCs in the waste handling facility was three times higher than at the landfill sites, being at highest 3000 microg/m3, considered to be the limit for discomfort. The use of personal protective equipment at work, thorough hand washing and changing clothes after the work shift are strongly recommended in the waste handling facility and the landfill sites. (+info
Talking trash: the economic and environmental issues of landfills.
The U.S. per-capita figure for garbage production has topped four pounds per person per day, and that amount is rising at roughly 5% per year. In the past, municipal solid waste was sent to the nearest local landfill or incinerator. But in 1988, the U.S. Environmental Protection Agency instituted the first federal standards for landfills, designed to make them safer. Over 10,000 small municipal landfills have since been consolidated into an estimated 3,500 newer, safer landfills, some of which are "megafills" that can handle up to 10,000 tons of waste a day. The new landfills are outfitted to prevent air and water pollution and limit the spread of disease by scavengers. Although the new landfills provide better controls against air and water pollution as well as an alternate source of municipal income, they are not entirely problem-free. Some experts believe the new landfill technology has not been properly tested and will therefore not provide protection in the long run. Others feel that poorer, less well-informed communities are targeted as sites for new landfills. In addition, many people that live near megafills, which may draw garbarge from several states, are unhappy about the noise, truck traffic, odors, and pests caused by the facilities. (+info
Trading trash: why the U.S. won't sign on to the Basel convention.
Environmentalists worry that hazardous wastes produced in industrialized nations are being dumped in cash-starved developing countries--the countries with the least political or economic clout to resist and the fewest resources for managing these toxic imports. Imported waste can pose a serious threat to the health of human populations and ecosystems if not managed appropriately. In 1989, the international community initiated efforts to reduce the flow of hazardous wastes from industrialized countries to developing countries by drafting a treaty known as the Basel Convention on the Control of Transboundary Wastes and their Disposal. The convention's mission is to strictly regulate the international transfer of hazardous wastes and to ensure that wastes are managed and disposed of in an environmentally sound manner. Although the United States supports the convention in theory, it remains the only industrialized country within the Organization for Economic Cooperation and Development yet to ratify it. However, legislation drafted by the Clinton administration that is soon to go before the 106th Congress could make the United States a party to the convention. (+info
Thauera mechernichensis sp. nov., an aerobic denitrifier from a leachate treatment plant.
A heterotrophic bacterial strain TL1T capable of aerobic denitrification was previously enriched in continuous culture from a landfill leachate treatment plant and isolated as a pure culture. The taxonomic position of this isolate within the beta-subclass of the Proteobacteria was determined by 16S rDNA sequence analysis and by conventional taxonomy including substrate spectrum, quinone type (ubiquinone Q-8) and cellular fatty acid composition. Detection of the specific polyamine 2-hydroxyputrescine supports the membership of strain TL1T in the beta-subclass of the Proteobacteria. The results of 16S rDNA sequencing showed that the strain clustered with, but was separate from, Thauera aromatica and Thauera selenatis. DNA-DNA hybridization experiments indicated that the new isolate represents a new species of the genus, for which the name Thauera mechernichensis is proposed; the type strain is DSM 12266T. (+info
Evaluation of nitrogen and organic matter balance in the feedlot as affected by level and source of dietary fiber.
A trial was conducted to determine the effect of level and source of dietary fiber on N and OM excretion by cattle on finishing diets. One hundred twenty steers were stratified by weight and allotted to one of the following treatments: 7.5% roughage (7.5% R), wet corn gluten feed (WCGF; 41.5% of dietary DM), and all-concentrate (All Con) diet. Cattle were fed for 87 d during the summer with 23.7 m2 of pen area per animal. Steers fed the WCGF diet had heavier final weights, greater DMI, and higher ADG (P < .01) than the 7.5% R and All Con treatments. Steers fed All Con had lower (P < .01) DMI than the other two treatments. Nitrogen and OM mass balances in the feedlot were quantified. Main components were nutrient input, retention, and excretion. Nitrogen and OM intake of steers fed WCGF were greater (P < .05) than those of steers fed the other treatments. The WCGF treatment had a greater percentage of fecal N output (P < .05). The All Con treatment had a greater (P < .01) percentage of urinary N than WCGF and 7.5% R diets. Steers fed the WCGF treatment excreted more (P < .01) OM compared with the other treatments, which led to more N and OM being removed in manure at cleaning. The All Con treatment had more (P < .01) N and OM in runoff than the other treatments. Nutrition can change site of fermentation, which affects the composition of excreted material; however, total amount of N excreted may be more important than route of excretion in decreasing N losses to the environment and maximizing recovery in manure. (+info
Exposure-response relationship between gastrointestinal problems among waste collectors and bioaerosol exposure.
OBJECTIVES: A high frequency of gastrointestinal problems has previously been reported for waste collectors. The present study relates the gastrointestinal problems to measurements of the bioaerosols that waste collectors are exposed to during work. METHODS: A job-exposure matrix was constructed from a combination of questionnaire data and field measurements. The questionnaire data were collected from 1747 male waste collectors and a comparison group of 1111 male municipal workers. Moreover a total of 189 full-shift personal samples was collected. The samples were used for characterizing the bioaerosol exposure described by viable fungi, total count of fungal spores, microorganisms, and endotoxins. RESULTS: In a multivariate analysis, high exposure to endotoxins was associated with nausea [prevalence proportion ratio (PPR) 1.60], and the risk of reporting nausea decreased with decreasing exposure so that workers with low exposure had the fewest reports (PPR 1.39) in the comparison with the unexposed group. High exposure to endotoxins was also associated with reports of diarrhea (PPR 5.60), and the risk of reporting diarrhea decreased with decreasing exposure so that the workers with low exposure had the fewest reports (PPR 3.02). The same pattern existed for exposure to fungi, for which high exposure resulted in the most reports (PPR = 4.59), and for diarrhea, for which low exposure resulted in the fewest reports (PPR = 3.15). CONCLUSIONS: An exposure-response relationship was found between nausea and endotoxin exposure and between diarrhea and exposure to both endotoxins and viable fungi. (+info