PubMed Health⌕ Search

Biomedical subjects

J N Lester

Publications and source records attributed to J N Lester.

At least 19 recordsLinked to original sources
PubMed2006

The occurrence and removal of selected pharmaceutical compounds in a sewage treatment works utilising activated sludge treatment.

Pharmaceutical substances have been detected in sewage effluents as well as receiving waters in many parts of the world. In this study, the occurrence and removal of a number of drug compounds were studied within a large sewage treatment plant in the south of England. Samples were processed using solid phase extraction and analysed using gas chromatography-mass spectrometry (GC-MS). The results demonstrate that ibuprofen, paracetamol, salbutamol and mefenamic acid were present in both the influent and effluent of the works while propranolol-HCl was not found above the limit of quantification in any sample. Elimination rates were circa 90% for each compound but several hundred nanograms per litre were still present in the final effluent.

Acetaminophen↗
PubMed2006

Monitoring losses of copper based wood preservatives in the Thames estuary.

Field trials were conducted at two sites in the Thames estuary to monitor losses of copper, chromium and arsenic from wood preservative treated timbers of varying sizes and treatment regimes. Results indicated that leaching tests conducted under standard laboratory conditions might overestimate losses compared to losses resulting from real environmental exposures. Amine copper treated wood was noted to leach higher levels of copper compared to chromated copper arsenate treated wood, and was therefore considered an inappropriate replacement biocide for fresh and marine construction purposes on this basis. Increases in copper concentrations in the outer sections of amine copper treated posts may have represented re-distribution of this component in this timber. No accumulation of metals was found in sediments surrounding field trial posts.

Adsorption↗
PubMed2005

Partitioning behavior of five pharmaceutical compounds to activated sludge and river sediment.

Pharmaceutical substances have been detected in sewage effluents as well as receiving waters in many parts of the world. To assess the fate and removal of these compounds within sewage treatment plants, an understanding of their partitioning behavior between the solid and aqueous phases is critical. Therefore, a preliminary study was conducted to ascertain an understanding of the binding behavior of five drug substances sorbing to the solid phase in a laboratory scale-activated sludge plant (Husmann unit). For comparison, uncontaminated river sediment was also used as a substrate. All of the compounds tested partitioned more readily to the sludge than the sediment, likely because of the former's higher organic carbon content. Partitioning to the solid phase correlated roughly with predicted log Kow values. A period of initial sorption was followed by a phase of desorption, and net absorption of the selected drugs (with the exception of mefenamic acid) after 5 hours of mixing was minimal.

Adsorption↗
PubMed2005

Butyltin compounds in a sediment core from the old Tilbury basin, London, UK.

Sections from a sediment core taken from the River Thames were analysed for butyltin species using gas chromatography with species-specific isotope dilution mass spectrometry. Results demonstrated that in most samples tributyltin concentrations of 20-60 ng/g accounted for <10% of the total butyltin species present, which is in agreement with data from other sediment samples which were historically contaminated with tributyltin. Vertical distribution of the organotin residues with depth throughout the core, with data on organochlorine compounds and heavy metals allowed for the construction of a consistent hypothesis on historical deposition of contaminated sediments. From this it was possible to infer that the concentrations of tributyltin in sediments deposited during the early 1960s were in the order of 400-600 microg/g by using degradation rate constants derived by other workers. Such values fall well within the range quoted for harbour sediments in the literature.

Environmental Monitoring↗
PubMed2005

Evaluation of environmental burdens associated with sewage treatment processes using life cycle assessment techniques.

Life cycle assessments of a range of wastewater treatment processes have been undertaken. At lower consent standards rotating biological contactors and biological filters exhibit lower environmental burdens for the required functionality than other process options. However, at tighter consents this distinction becomes less clear. Attempts to reduce environmental burdens should focus on operational energy requirements (which dominate burden profiles and, where appropriate, on synthetic materials used for bio-mass growth). However, differences between dry and operational weight, and the consequent size of necessary foundation structures are likely to limit opportunities for reducing overall burden profiles through material substitution. Comparison of processes across population equivalents suggests economies of scale may favour adopting larger scale plant, although there are additional factors yet to be included in this analysis. Furthermore, adopting different waste disposal routes during the demolition phase is unlikely to have a distinct impact on burden profiles.

Biodegradation, Environmental↗
PubMed2004

Removal of organotins during sewage treatment: a case study.

Discharge consents for tributyltin (TBT) from wastewater treatment works in the UK are set by the Environment Agency. These values are normally derived from the Environmental Quality Standards for concentrations of TBT in the receiving water, based on the volume of effluent discharged and subsequent dilution within the environment. In this study, a sampling program was designed to monitor concentrations of TBT (and other organotins) in the influent and effluent at each stage of treatment. Sampling was undertaken at 3 hourly intervals, over 24 hours, at 8 locations throughout the works for five days. Organotin concentrations were determined using capillary gas chromatography with flame photometric detection. The results demonstrated that TBT was consistently present in the influent at concentrations of approximately 0.1 microg l(-1). However, a "pulse" of TBT and monobutyltin (MBT) was observed on the third day when the concentration of TBT and MBT in the influent increased to 14 microg l(-1). This "pulse" of TBT and MBT was also observed as the wastewater passed through the unit treatment processes. Concentrations of both compounds were much reduced in the final effluent (TBT 2.5 microg l(-1) and MBT 6.9 microg l(-1)). Over the entire period, the average removal of TBT during primary treatment was 81%, and during secondary biological treatment was 71%. The overall removal efficiency of the plant, taking into account the recycling of returned liquors was 86% between influent and effluent for TBT. Removal efficiency of TBT was correlated to that of suspended solids, and it was demonstrated that on days when suspended solids removal was low, TBT removal was also reduced. The mass flow of organotins through the plant indicated that the majority of TBT was concentrated into the sewage sludge. Concentrations of TBT in sludge at the plant were approximately 18 microg kg(-1) (dry weight).

Organotin Compounds↗
PubMed2004

Analytical methods for the determination of alkylphenolic surfactants and polybrominated diphenyl ethers in wastewaters and sewage sludges. I a review of methodologies.

Alkylphenolic surfactants (alkylphenol polyethoxylates) and the polybrominated diphenyl ether flame retardants are important environmental contaminants and have been implicated as endocrine disrupters. Both groups of compounds have come under increasing scrutiny from legislators and there are proposals to curb their use. However, these compounds continue to enter the environment and there is a need to determine their occurrence, fate and behaviour throughout the hydrosphere and in wastewater treatment processes to determine mass fluxes and sources. This paper reviews analytical methods for their determination in the aqueous and solid (sediment / sludge) phase. Extraction, cleanup and quantification by gas and liquid chromatographic (GC and LC) techniques linked to mass spectrometric (MS) detectors are considered. The literature indicates that for the alkylphenols research papers favour the use of LC/MS which is more amenable to determination of more highly ethoxylated oligomers, however, standard methods focus on GC/MS and the less ethoxylated oligomers and parent alkylphenols. The use of GC with negative chemical ionisation MS techniques predominates for the analysis of polybrominated diphenyl ethers.

Chemistry Techniques, Analytical↗
PubMed2004

Quantifying uncertainties in the assessment of sediment quality: statistical criteria and guidelines for sediment quality assessments.

Current sediment quality guidelines generally adopt a tiered approach in order to assess sediment quality more cost-effectively. The uncertainties involved in the tiered approach of an integrative assessment, however have not been quantified resulting in a risk of committing type I error or type II error at the final confirmatory stage. This study develops statistical criteria and guidelines for the sediment chemistry component of an integrative assessment of sediment quality. At the tier 1 screening stage, historical data or an initial survey is required to determine the minimum sample numbers that will be required to be representative of the study site. Understanding the guiding principles which have underpinned the setting of sediment quality criteria for contaminant is an important factor in tier 1 evaluations. To reduce cost and uncertainty in data, sampling should include the least number of samples necessary to minimise uncertainties by estimating the probability distribution function (which represents the variability of the natural environment at the location of concern), with subsequent application of kriging and sequential simulation methods on data obtained. Implementation of statistical criteria and guidelines in sediment quality assessments can provide a foundation for a further quantitative cost/benefit analysis and decrease the risk of committing type I and type II statistical errors at later classification stages.

Environmental Monitoring↗
PubMed2004

Analytical methods for the determination of alkylphenolic surfactants and polybrominated diphenyl ethers in wastewaters and sewage sludges. II method development.

Analytical methods for the determination of two groups of compounds, the non-polar alkyl phenols along with their more polar ethoxylates, and the hydrophobic polybrominated flame retardants in wastewater samples have been developed. The methods allow for determination of the analytes in both the aqueous and solid phases, which were separated by centrifugation and filtration. Extraction from the aqueous phase involved the use of SPE for the surfactants, however, liquid-liquid extraction was found to be more efficient for the PBDE. Alkyl phenols and their ethoxylates were extracted from the solid phase by shaking with solvent and Soxhlet was used for extraction of PBDE. Sample cleanup was based on alumina columns for the PBDE and surfactants when extracted form solids. Quantification of surfactants utilised LC-MS with ESI in both positive and negative ionisation mode, and GC-MS (NCI) was used to determine the PBDE, with the exception of the deca congener, where a 10 m column installed on GC-ECD resulted in short run times and reduced thermal decomposition. Method recoveries for the surfactants were above 80%, and for PBDE 92.5% from the solid phase and 95+/-5% from the liquid phase.

Chromatography, Liquid↗
PubMed2003

Public perceptions and attitudes towards an established managed realignment scheme: Orplands, Essex, UK.

Where appropriate, managed realignment is the preferred policy option for sustainable coastal defences in the UK, since it provides both economic and ecological advantages. Until recently however, research has failed to address the social implications of this policy option having only acknowledged that communities in general, show reluctance in conceding land to the sea. Orplands managed realignment scheme is the third in a series of case studies to address a variety of social issues, but with a particular focus on the public acceptance of schemes and public confidence in the Environment Agency. It is hypothesised that local residents will be more accepting of a realignment scheme the longer it is in the public domain, rather than at its inception or construction. This paper presents findings from the Orplands scheme and demonstrates that overall scheme acceptance was greater at this site in comparison to previous case studies. Despite this, respondents did not show any more confidence in the Environment Agency and this has been attributed to their general scepticism towards a statutory body and the lack of recent contact between the various stakeholders. It is suggested that the development of criteria for consultation and public participation would facilitate public acceptance of managed realignment schemes.

Adolescent↗
PubMed2003

Balanced scorecard investment appraisal in the water industry of England and Wales.

Previous work has shown that while most conventional investment appraisal techniques appear ill-suited for use in the water industry of England and Wales, the Balanced Scorecard (BSC) offers considerable potential as an investment decision making tool. This study accounts for much of the criticism of the BSC technique, proposing methodological changes to overcome these difficulties. A more comprehensive treatment of the modified methodology, illustrated by BSC development and application flowcharts, demonstrates how this technique might operate in practice.

Commerce↗
PubMed2002

Prediction of the bioaccumulation factors and body burden of natural and synthetic estrogens in aquatic organisms in the river systems.

This study undertakes an initial prediction of the bioaccumulation factors and body burden of the steroid estrogens, estrone, estradiol, estriol and ethinylestradiol in a range of aquatic organisms (plankton, benthic and free-living invertebrates and fish) in river systems using a food-web model. These data are compared to that derived from less complex predictions based on octanol-water partition coefficient and molecular connectivity index. The model predicted that bioaccumulation of steroid estrogens occurred in all organisms, however, the values were small, and the maximum and minimum bioaccumulation factors in this study were found in the fish at the lowest trophic level with ethinylestradiol (332) and the fish at the highest trophic level with estriol (1.8), respectively. Moreover, the bioaccumulation factors were sensitive to the metabolic rates of the estrogens in the free living organisms, while the concentration of estrogens in sediment was a significant factor in determining these values in benthic invertebrates. Biomagnification contributed little to the overall bioaccumulation, but the importance increased in fish exposed to ethinylestradiol. The predicted bioaccumulation factors from the food web model were generally smaller than the calculated bioconcentration factors from the simpler octanol-water partition coefficient/molecular connectivity index based estimates. Compared to literature measured data, the predicted values for fish were approximately 1000 times less than the values observed in laboratory tests, while for invertebrates, the modeled values were less than two orders of magnitude below laboratory results. However, the model predicted a similar bioconcentration factor for plankton in relation to experimental data for Chlorella vulgaris for estrone and estriol.

Animals↗
PubMed2002

Developing a sustainable energy strategy for a water utility. Part I: A review of the UK legislative framework.

Increasing political effort to improve water quality across the UK and Europe has led to water and sewerage companies investing heavily in high-tech wastewater treatment plants capable of producing high quality effluents. Consequently, amounts of bought-in electricity used for wastewater treatment has and will continue to increase significantly over coming years, while greater provision of enhanced sewage treatment also produces greater volumes of sewage sludge requiring treatment and disposal. Over the same period, tougher controls on the quality of biosolids applied to agricultural land have also been introduced, while there has been an international attempt to reduce the use of fossil-fuel derived power sources because of concerns over global warming. The latter has brought about the introduction of financial instruments, such as the Climate Change Levy, to curb energy use, promote energy efficiency and encourage the development of renewable energy technologies. These factors are set to drive-up the costs of providing adequate sewage treatment services, while at the same time, a tough regulatory line taken to control profits on regional monopolies held by the UK water companies will significantly reduce their revenues over the period 2000-05. The result is that, financially, UK water and sewerage companies face their most challenging period since privatisation in 1989. This paper briefly outlines the current regulations relating to water quality and energy use that will affect water company operations over coming years.

Conservation of Natural Resources↗
PubMed2002

Developing a sustainable energy strategy for a water utility. Part II: A review of potential technologies and approaches.

Environmental legislation is increasing the amounts of bought-in electricity required for sewage treatment, and generating larger volumes of sewage sludge to be treated and disposed of. Concurrently, concerns over global warming and food safety from sewage sludge recycling on agricultural land is augmenting the costs of conventional sewage and sludge treatment technologies and practices. This paper reviews some emerging technologies and practices that may assist in mitigating these problems in the future. In addition, a number of potential renewable energy technologies available to water companies are reviewed. Results suggest that through the take-up of new technologies, current and future water quality standards could be delivered in a more sustainable way. However, this series of papers also highlights that institutional and political conflicts may have inadvertently failed to recognise the wider effects of improving water quality and lessened the financial support necessary for their widespread take-up. It is also suggested that through the use of a Strategic Environmental Assessment (SEA) approach, stakeholders could gain a better understanding of the broader environmental effects of achieving certain water quality standards and develop policy and long-term investment strategies accordingly. However, to fulfill the information requirements of an SEA, an appropriate appraisal tool that considers many of these factors in unison is required, and a possible technique is suggested.

Conservation of Natural Resources↗
PubMed2002

Aquatic environmental assessment of the top 25 English prescription pharmaceuticals.

An environmental assessment is presented for the 25 most used pharmaceuticals in the National Health Service (NHS) in England in 2000. Predicted environmental concentrations (PECs) for the aquatic environment were calculated using conservative assumptions and all PECs exceeded 1 ng 1 (-1). The calculation of predicted no-effect concentration (PNEC) based on aquatic toxicity data from the literature was possible for eleven of the pharmaceuticals. PNECs were predicted with ECOSAR for 12 of the remaining 14 but no data was available for two of the compounds. The PEC/ PNEC ratio exceeded one for Paracetamol, Amoxycillin, Oxytetracycline and Mefenamic acid. Comparisons of the predicted concentrations of the compounds in sewage sludge based on either calculated sludge-water coefficients (Kd), octanol water coefficients (K(ow)), acid base constants (pKa) or environmental modelling revealed large variations. No toxicity data was available for the terrestrial environment and no assessment was made.

England↗