In‐well sediment incubators to evaluate microbial community stability and dynamics following bioimmobilization of uranium

An in‐well sediment incubator (ISI) was developed to investigate the stability and dynamics of sediment‐associated microbial communities to prevailing subsurface oxidizing or reducing conditions. Herein we describe the use of these devices at the Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) site. During a seven‐month period in which oxidized Rifle Aquifer background sediment (RABS) were deployed in previously biostimulated wells under iron‐reducing conditions, cell densities of known iron‐reducing bacteria, including Geobacteraceae, increased significantly, showing the microbial community response to local subsurface conditions. Phospholipid fatty acid (PLFA) profiles of RABS following in situ deployment were strikingly similar to those of adjacent sediment cores, suggesting ISI results could be extrapolated to the native material of the test plots. Results for ISI deployment with laboratory‐reduced sediments showed only slight changes in community composition and pointed toward the ability of the ISI to monitor microbial community stability and response to subsurface conditions. © 2009 Wiley Periodicals, Inc.     

Replacement of a multiple hearth by a fluid bed incinerator the Greensboro case history

The incinerator at the T.Z. Osborne Plant in Greensboro, North Carolina burns sludge from its own waste water treatment plant and sludge pumped from the nearby North Buffalo plant. The two plants have a combined capacity of 36 million gallons per day of wastewater. Because of the age of and increasing high maintenance on the existing multiple hearth incinerator, and the need to increase treatment capacity, the Osborne plant concluded a study in 1992 evaluating its options for future municipal sewage sludge disposal. Options which were evaluated during the study included; (i) rehabilitation of the existing eight-year old multiple hearth unit; (ii) addition of a new multiple hearth; (iii) addition of a new fluid bed system; (iv) drying, composting, or land application. The chosen option, based on both economic and environmental considerations, was a new fluid bed system with a capacity of 2.55 tons per hour, approximately double that of the existing multiple hearth. Design of the new fluid bed system began in December 1994 and equipment delivery for the incineration system was begun in April 1995. Initial operation occurred in August 1996. Primary and secondary sludge, dewatered to 28% dry solids by centrifuge, is delivered by piston pumps to the twenty-foot freeboard ID incinerator. A shell and tube heat exchanger recuperates heat from the exhaust gas and preheats the combustion air to 1250°F, resulting in minimal auxiliary fuel use. The air pollution control device is a high-energy Tandem Nozzle® scrubber. Greensboro was the initial installation of this scrubber design on a fluid bed incinerator and its characteristics and performance are discussed. Ash is dewatered in an ash thickener/belt press system prior to disposal to landfill. The system includes a state of the art Programmable Logic Controller (PLC) system for computer control of the operation. The unit was commissioned in August 1996 and has been in continuous operation since that time except for a one week inspection and maintenance shutdown in February 1999. The plant operates 24 h/day, 7 days per week. The initial performance test showed the system to readily meet federal and state air emission standards. Particulate released was 0.002 grains per dry standard cubic foot, carbon monoxide was 22.5 parts per million volumetric (ppmv) and opacity was 0.4%. These results show a significant emission reduction with the fluid bed when compared to the multiple hearth. Annual tests conducted since then and continuous emission monitoring have shown the unit to be in consistent compliance. Since the fluid bed system became operational, the old multiple hearth system has been maintained on standby as a backup, but its use has not been required. Operational experience is discussed, the most interesting of which is the relatively trouble-free operation. The minor problems which occurred and their solutions are detailed. Also included is a comparison of operation and maintenance experience of the fluid bed and the multiple hearth. Current sludge disposal actual cost data are also provided including the average cost per ton of dry solids treated. The almost three years of operational experience to date has shown that the decision to install a new fluid bed system was the correct one on both an environmental and economic basis. It has provided benefits to all interested parties — the wastewater treatment plant, the regulators, the taxpayers, and the surrounding community.     

Divergent perspectives on water resource sustainability in a public–policy–science context

Diverging perspectives toward environmental problems, their causes, and solutions can exacerbate controversy in participatory decision making. Past research has examined the lay–expert divide in perceptions about diverse risks, but relatively few studies have examined multidimensional perspectives on water scarcity across expert groups with different knowledge systems. We address this gap by examining conflicting perspectives across ‘lay’ residents and academic and policymaking ‘experts’ in Phoenix, AZ. We analyze ecological concern about water issues, risk perceptions regarding the factors contributing to scarcity, and policy attitudes pertaining to resource management alternatives. All three groups expressed substantial concern for broad-scale water issues, especially drought. Residents exhibited a heightened tendency to blame other people for water scarcity, in addition to opposition toward stringent approaches such as water pricing. While strongly supporting the acquisition of more supplies, policymakers exhibited lower concern about regional water use rates while displacing blame away from anthropogenic causes compared to both residents and academic experts. Scientists, on the other hand, stressed the need for stricter regulation of water demand. Findings point to the challenges of meshing different knowledge systems for collaborative research and policy making.     

Cross-hybridization of the chromosome 13/21 alpha satellite DNA probe to chromosome 22 in the prenatal screening of common chromosomal aneuploidies by fish

In a routine application of commercially available centromeric DNA probes for the prenatal screening of common trisomies involving the autosomes 13, 18, and 21, and sex chromosomes, four cases of discrepancy between fluorescence in situ hybridization (FISH) results and follow-up cytogenetic analysis were observed from a total of 516 cases of amniocentesis. In three of these cases, the results were false negative, and in one false positive. In this case, amniocentesis was performed because of a positive triple test in a 34-year-old woman with previous infertility treatment. The alpha satellite DNA probe for chromosomes 13/21 revealed five signals in 50 per cent of uncultured amniocytes, while standard cytogenetic analysis showed a normal karyotype. FISH analysis on metaphase chromosomes demonstrated the location of the additional signal in the centromeric region of chromosome 22. This additional signal was also present in the centromeric region of chromosome 22 of the mother, providing evidence for a possible inherited polymorphism in chromosome 22 responsible for unspecific hybridization with the alpha satellite probe for chromosomes 13/21 in this case. The observed polymorphism in centromeric regions may contribute to unreliability of the use of the 13/21 alpha satellite probe for prenatal screening by FISH.