Compositional and physicochemical changes in waste materials and biogas production across 7 landfill sites in UK.

The aim of this study was to evaluate the spatial distribution of the paper and fines across seven landfill sites (LFS) and assess the relationship between waste physicochemical properties and biogas production. Physicochemical analysis of the waste samples demonstrated that there were no clear trends in the spatial distribution of total solids (TS), moisture content (MC) and waste organic strength (VS) across all LFS. There was however noticeable difference between samples from the same landfill site. The effect of landfill age on waste physicochemical properties showed no clear relationship, thus, providing evidence that waste remains dormant and non-degraded for long periods of time. Landfill age was however directly correlated with the biochemical methane potential (BMP) of waste; with the highest BMP obtained from the most recent LFS. BMP was also correlated with depth as the average methane production decreased linearly with increasing depth. There was also a high degree of correlation between the Enzymatic Hydrolysis Test (EHT) and BMP test results, which motivates its potential use as an alternative to the BMP test method. Further to this, there were also positive correlations between MC and VS, VS and biogas volume and biogas volume and CH4 content. Outcomes of this work can be used to inform waste degradation and methane enhancement strategies for improving recovery of methane from landfills.

Evaluating leachate recirculation with cellulase addition to enhance waste biostabilisation and landfill gas production.

The effect of leachate recirculation with cellulase augmentation on municipal solid waste (MSW) biostabilisation and landfill gas production was investigated using batch bioreactors to determine the optimal conditions of moisture content, temperature and nutrients. Experimentation was thereafter scaled-up in 7L bioreactors. Three conditions were tested including (1) leachate recirculation only, (2) leachate recirculation with enzyme augmentation and (3) no leachate recirculation (control). Cumulative biogas production of the batch tests indicated that there was little difference between the leachate and control test conditions, producing on average 0.043m(3)biogaskg(-1) waste. However the addition of cellulase at 15×10(6)Utonne(-1) waste doubled the biogas production (0.074m(3)biogaskg(-1) waste). Similar trend was observed with the bioreactors. Cellulase addition also resulted in the highest COD reduction in both the waste and the leachate samples (47% and 42% COD reduction, respectively). In both cases, the quantity of biogas produced was closer to the lower value of theoretical and data-based biogas prediction indicators (0.05-0.4m(3)biogaskg(-1) waste). This was likely due to a high concentration of heavy metals present in the leachate, in particular Cr and Mn, which are known to be toxic to methanogens. The cost-benefit analysis (CBA) based on the settings of the study (cellulase concentration of 15×10(6)Utonne(-1) waste) showed that leachate bioaugmentation using cellulase is economically viable, with a net benefit of approximately €12.1million on a 5Mt mixed waste landfill.

Sustainable landfill leachate treatment using refuse and pine bark as a carbon source for bio-denitrification.

Raw and 10-week composted commercial garden refuse (CGR) materials and pine bark (PB) mulch were evaluated for their potential use as alternative and sustainable sources of carbon for landfill leachate bio-denitrification. Dynamic batch tests using synthetic nitrate solutions of 100, 500 and 2000 mg NO3 L(-1) were used to investigate the substrate performance at increasing nitrate concentrations under optimal conditions. Further to this, sequential batch tests using genuine nitrified landfill leachate with a concentration of 2000 mg NO3 L(-1) were carried out to evaluate substrates behaviour in the presence of a complex mixture of chemicals present in leachate. Results showed that complete denitrification occurred in all conditions, indicating that raw and composted CGR and PB can be used as sustainable and efficient media for landfill leachate bio-denitrification. Of the three substrates, raw garden refuse yields the fastest denitrification rate followed by 10-week composted CGR and PB. However, the efficiency of the raw CGR was lower when using genuine leachate, indicating the inhibitory effect of components of the leachate on the denitrification process. Ten-week composted CGR performed optimally at low nitrate concentrations, while poor nitrate removal ability was found at higher nitrate concentrations (2000 mg L(-1)). In contrast, the PB performance was 3.5 times faster than that of the composted garden refuse at higher nitrate concentrations. Further to this, multi-criteria analysis of the process variables provided an easily implementable framework for the use of waste materials as an alternative and sustainable source of carbon for denitrification.

Effectiveness of an occupational and environmental medicine curriculum as indicated by evaluation of medical student performance on an objective structured clinical examination.

Medical students must learn to recognize occupational and environmental-related illness. An occupational and environmental medicine curriculum can achieve this goal. The curriculum must be evaluated to ensure that medical students are learning to recognize exposure-related health conditions and to evaluate if this ability correlates with medical interviewing skills. A case, formatted for an Objective Structured Clinical Examination (OSCE), was developed to evaluate student performance on an exposure-related clinical problem. The OSCE results were analyzed to identify the areas that differentiated the students who recognized an exposure-related medical condition from those who did not. We conclude that an OSCE is an effective curriculum evaluation tool to assess whether a core occupational and environmental-related curriculum is contributing to student learning in exposure history-taking and associated clinical reasoning skills.

Assessing medical students' perceptions of mistreatment in their second and third years.

PURPOSE: To study medical students' perceptions of mistreatment in their second and third years of training. METHOD: A questionnaire was distributed at Wayne State University School of Medicine to the class of 1993 at the end of its third year and to the class of 1994 at the end of its second and third years. The students were asked if they had been subjected to various forms of mistreatment; the third-year students were asked to rate their perceptions of each clinical department's response to them on the basis of gender and race-ethnicity, as well as their overall treatment. The students also completed demographic information about age, gender, and marital status, number of children, and race-ethnicity. Results were analyzed using chi-square statistics, multivariate statistical analyses, analyses of variance, and Duncan's post-hoc comparisons. RESULTS: The response rate for the class of 1993 was 71.5%; response for the class of 1994 were 66.9% in their second year and 75.2% in their third year; 41.7% were women, and the racial-ethnic breakdown was 71.2% white/Caucasian, 11.7% black/African American and 16.8% other. There was a significant difference between the percentages of second-year and third-year students reporting any experience of mistreatment (37.2% vs 75.8%, p < .001). Canonical correlation analysis revealed bias in the third year based on gender (p < .0001) and race-ethnicity (p < .0002); both variates were related to sexual humor. The students' perceptions of mistreatment were lowest for family medicine and highest for obstetrics-gynecology and surgery. Perceptions of mistreatment in departments varied significantly by gender and race-ethnicity. The nonwhite males reported the least favorable treatment in most departments. CONCLUSION: Marked variability in the students' perceptions of mistreatment within departments suggest that a variety of approaches will be required to improve the medical training environment.

Experience with an end-of-life practice at a university hospital.

OBJECTIVE: To describe a 10-yr experience with an end-of-life practice in a hospital. DESIGN: A nonexperimental, prospective, descriptive design was used to record variables from a convenience sample of patients transferred to the Comprehensive Supportive Care Team. SETTING: Detroit Receiving Hospital is an urban, university-affiliated, Level I trauma/emergency hospital. PATIENTS: Patients who are not expected to survive hospitalization, and for whom a decision has been made to focus care on palliative interventions, are candidates for care by this practice. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patient demographics, including the following information: age, gender; diagnoses; illness severity; mortality rate; and disposition. Measures of resource utilization included: referral sources; Therapeutic intervention Scoring System values; bed costs; and length of hospital stay. Satisfactory patient/family care with a measurable reeducation in the use of resources can be achieved in the hospital setting. CONCLUSIONS: A hands-on approach to the care of dying patients by this specialty, palliative care service has provided patients, families, and clinicians with the type of support needed for satisfactory end-of-life care. A summary of our experience may be useful to others.

Development of a comprehensive supportive care team for the hopelessly ill on a university hospital medical service.

We developed a supportive care service for a university hospital medical service that serves a socially and medically disadvantaged urban population. The team includes a faculty physician and a clinical nurse specialist who provide primary medical care, family support, and in-service guidance to hospital staff about ethical issues. A multidisciplinary approach incorporates nursing, pastoral care, social work, and other hospital services. We report our experience from November 1985 through May 1987, during which time 222 patients were referred to the team; 212 patients were accepted. The goals and operation of the service are described. The most common (n = 62, 29%) diagnosis on referral was global central nervous system anoxia following cardiopulmonary arrest. Other severe neurological conditions accounted for an additional 79 patients (37%). Comparison of patients on the service with a similar group revealed no difference in survival rate, although hospital length of stay and charges were progressively reduced after implementation of the service. This approach to the care of hopelessly ill patients may serve as an alternative method of treatment in similar hospital settings.

KIE: The authors document the first 19 months of a service dedicated to the care of hopelessly ill patients in a teaching hospital. A comprehensive supportive care team (CSCT) was established to ensure a humane, uniform, and consistent approach to the care of patients for whom aggressive care is no longer warranted. The goals and operation of the CSCT are described, including the components of patient evaluation and development of treatment plans. Results of a study of 212 patients accepted by the CSCT are reported. The authors conclude that the service successfully provided conservative but comprehensive care for the hopelessly ill, and that it increased awareness of ethical issues among hospital personnel, patients, and families.

Evaluation of blood pressure during early alcohol withdrawal.

Ninety-five patients undergoing early alcohol withdrawal were observed for a five-day period in a non-hospital facility to evaluate the natural history of blood pressure change during this period. Patients under 30 years old developed a significant increase in systolic pressure on the second abstinent day, decreasing a mean of 10 mm Hg by the fourth abstinent day. With increasing age there was a progressively smaller rise in systolic pressure. Multivariate analysis showed a history of hypertension, delirium tremens, seizures, initial pulse, race, and sex not to be predictive of blood pressure change. Diastolic pressure was unaffected. Etiology of this difference requires further study. There were no hypertensive complications in this group. Patients undergoing early withdrawal need not be treated for changes in blood pressure without evidence of end organ damage or severe hypertension.

Human leptospirosis in Detroit and the role of rats as chronic carriers.

Human leptospirosis was diagnosed in three patients from Detroit General Hospital. Epidemiological studies of these cases revealed heavy rat infestations in the residences of two of the patients. Leptospires serotype icterohaemorrhagiae were isolated from the rats and one of the patients. Cultural isolation was attempted from numerous blood and urine samples from each patient. Media containing different selective contaminant inhibitor substances was also utilized. Only two samples were culturally positive. It appears that very few viable cells are shed by human patients intermittently. Clinical reports and leptospirosis diagnosis are reported for each of the cases. The agglutinin-absortion test proved to be helpful in elucidating the true etiologic agent in the absence of cultural isolation. A serological survey for leptospirosis was conducted among swine slaughterhouse workers in Detroit. Significant titres to Leptospira pomona were observed.