2,229 research outputs found
Biochar from Pyrolysis of Biosolids for Nutrient Adsorption and Turfgrass Cultivation
At water resource recovery facilities, nutrient removal is often required and energy recovery is an ever-increasing goal. Pyrolysis may be a sustainable process for handling wastewater biosolids because energy can be recovered in the py-gas and py-oil. Additionally, the biochar produced has value as a soil conditioner. The objective of this work was to determine if biochar could be used to adsorb ammonia from biosolids filtrate and subsequently be applied as a soil conditioner to improve grass growth. The maximum carrying capacity of base modified biochar for NH3−N was 5.3 mg/g. Biochar containing adsorbed ammonium and potassium was applied to laboratory planters simulating golf course putting greens to cultivate Kentucky bluegrass. Planters that contained nutrient-laden biochar proliferated at a statistically higher rate than planters that contained biosolids, unmodified biochar, peat, or no additive. Nutrient-laden biochar performed as well as commercial inorganic fertilizer with no statistical difference in growth rates. Biochar from digested biosolids successfully immobilized NH3−N from wastewater and served as a beneficial soil amendment. This process offers a means to recover and recycle nutrients from water resource recovery facilities
Convergence of detrital stoichiometry predicts thresholds of nutrient-stimulated breakdown in streams
Nutrient enrichment of detritus‐based streams increases detrital resource quality for consumers and stimulates breakdown rates of particulate organic carbon (C). The relative importance of dissolved inorganic nitrogen (N) vs. phosphorus (P) for detrital quality and their effects on microbial‐ vs. detritivore‐mediated detrital breakdown are poorly understood. We tested effects of experimental N and P additions on detrital stoichiometry (C:N, C:P) and total and microbial breakdown (i.e., with and without detritivorous shredders, respectively) of five detritus types (four leaf litter species and wood) with different initial C : nutrient content. We enriched five headwater streams continuously for two years at different relative availabilities of N and P and compared breakdown rates and detrital stoichiometry to pretreatment conditions. Total breakdown rates increased with nutrient enrichment and were predicted by altered detrital stoichiometry. Streamwater N and P, fungal biomass, and their interactions affected stoichiometry of detritus. Streamwater N and P decreased detrital C:N, whereas streamwater P had stronger negative effects on detrital C:P. Nutrient addition and fungal biomass reduced C:N by 70% and C:P by 83% on average after conditioning, compared to only 26% for C:N and 10% for C:P under pretreatment conditions. Detritus with lowest initial nutrient content changed the most and had greatest increases in total breakdown rates. Detrital stoichiometry was reduced and differences among detritus types were homogenized by nutrient enrichment. With enrichment, detrital nutrient content approached detritivore nutritional requirements and stimulated greater detritivore vs. microbial litter breakdown. We used breakpoint regression to estimate values of detrital stoichiometry that can potentially be used to indicate elevated breakdown rates. Breakpoint ratios for total breakdown were 41 (C:N) and 1518 (C:P), coinciding with total breakdown rates that were ~1.9 times higher when C:N or C:P fell below these breakpoints. Microbial and shredder‐mediated breakdown rates both increased when C:N and C:P were reduced, suggesting that detrital stoichiometry is useful for predicting litter breakdown dominated by either microbial or shredder activity. Our results show strong effects of nutrient enrichment on detrital stoichiometry and offer a robust link between a potential holistic nutrient loading metric (decreased and homogenized detrital stoichiometry) and increased C loss from stream ecosystems
Assessing the importance of a self-generated detachment process in river biofilm models
1. Epilithic biofilm biomass was measured for 14 months in two sites, located up- and downstream of the city of Toulouse in the Garonne River (south-west France). Periodical sampling provided a biomass data set to compare with simulations from the model of Uehlinger, Bürher and Reichert (1996: Freshwater Biology, 36, 249–263.), in order to evaluate the impact of hydraulic disturbance.
2. Despite differences in application conditions (e.g. river size, discharge, frequency of disturbance), the base equation satisfactorily predicted biomass between low and high water periods of the year, suggesting that the flood disturbance regime may be considered a universal mechanism controlling periphyton biomass.
3. However modelling gave no agreement with biomass dynamics during the 7-month long low water period that the river experienced. The influence of other biomass-regulating factors (temperature, light and soluble reactive phosphorus) on temporal biomass dynamics was weak.
4. Implementing a supplementary mechanism corresponding to a temperature-dependent self-generated loss because of heterotrophic processes allowed us to accurately reproduce the observed pattern: a succession of two peaks. This case study suggests that during typical summer low water periods (flow stability and favourable temperature) river biofilm modelling requires self-generated detachment to be considered
Can physical activity be used to maintain cognitive function in nursing home residents with dementia? A literature review
Background: Dementia is a noncommunicable disease with no effective prevention, treatment or cure. Evidence is emerging for the use of exercise to decelerate cognitive decline; however, few studies exist among nursing home residents and an optimum exercise protocol is yet to be determined. Objectives: To determine the effectiveness of physical activity in maintaining cognitive function in nursing home residents with dementia. Methods: Databases searched included CINAHL, MEDLINE complete, SPORTDiscus and ScienceDirect. Six relevant studies were identified and critically appraised using the Effective Public Health Practice Project Quality Assessment Tool. Results: All trials included different exercise programmes with various activity types and duration; all control interventions were social activities. Three studies demonstrated improved cognition in the intervention group, whilst one study observed a slower decline. Four studies found statistically significant cognitive decline in the control groups. Two studies observed no significant changes in either the intervention or control groups. Overall, there is moderate-to-moderate evidencestrong evidence that physical activity can effectively maintain cognitive function in nursing home residents with dementia. Conclusions: All interventions had a favourable effect on cognition. Results suggest that aerobic exercise of longer duration may be most effective for those with mild-to-moderate cognitive impairment; whilst multimodal programmes may be most effective for moderate-to-severe dementia. Combining an exercise programme with standard daily activities appears no more effective than exercise alone. Future research should aim to determine an optimum exercise protocol and whether the positive effects on cognition can be maintained long term with continued exercise
Common Goods for Health : Economic Rationale and Tools for Prioritization
This paper presents the economic rationale for treating Common Goods for Health (CGH) as priorities for public intervention. We use the concept of market failure as a central argument for identifying CGH and apply cost-effectiveness analysis (CEA) as a normative tool to prioritize CGH interventions in public finance decisions. We show that CGH are consistent with traditional lists of public health core functions but cannot be identified separately from non-CGH activities in such lists. We propose a public finance decision tree, adapted from existing health economics tools, to identify CGH activities within the set of cost-effective interventions for the health sector. We test the framework by applying it to the 2018 Disease Control Priority (DCP) list of interventions recommended for public funding and find that less than 10% of cost-effective interventions unconditionally qualify as CGH, while another two-thirds may or may not qualify depending on context and form. We conclude that while CEA can be used as a tool to prioritize CGH, the scarcity of such analyses for CGH interventions may be partly responsible for the lack of priority given to them. We encourage further research to address methodological and resource challenges to assessing the cost-effectiveness of CGH intervention packages, in particular those involving large investments and long-term benefits
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Exploring Public Health's roles and limitations in advancing food security in British Columbia
OBJECTIVES: This research analyzes the roles and limitations of Public Health in British Columbia in advancing food security through the integration of food security initiatives into its policies and programs. It asks the question, can Public Health advance food security? If so, how, and what are its limitations?
METHODS: This policy analysis merges findings from 38 key informant interviews conducted with government and civil society stakeholders involved in the development of food security initiatives, along with an examination of relevant documents. The Population Health Template is used to delineate and analyze Public Health roles in food security.
RESULTS: Public Health was able to advance food security in some ways, such as the adoption of food security as a core public health program. Public Health's leadership role in food security is constrained by a restricted mandate, limited ability to collaborate across a wide range of sectors and levels, as well as internal conflict within Public Health between Food Security and Food Protection programs.
CONCLUSIONS: Public Health has a role in advancing food security, but it also faces limitations. As the limitations are primarily systemic and institutional, recommendations to overcome them are not simple but, rather, require movement toward embracing the determinants of health and regulatory pluralism. The results also suggest that the historic role of Public Health in food security remains salient today
Decay of escherichia coli in soil following the application of biosolids to agricultural land
The decay of Escherichia coli in a sandy loam soil, amended with enhanced and conventionally treated biosolids, was investigated in a field experiment following spring and autumn applications of sewage sludge. Control soils, without the application of biosolids, were also examined to determine the background indigenous populations of E. coli which are present in the environment. The survival of indigenous E. coli and populations of E. coli applied to soil in biosolids, is assessed in relation to environmental factors influencing pathogen-decay processes in soil
Breast-milk iodine concentration declines over the first 6 mo postpartum in iodine-deficient women.
BACKGROUND: Little is known about the iodine status of lactating mothers and their infants during the first 6 mo postpartum or, if deficient, the amount of supplemental iodine required to improve status. OBJECTIVE: The objective was to determine maternal and infant iodine status and the breast-milk iodine concentration (BMIC) over the first 6 mo of breastfeeding. DESIGN: A randomized, double-blind, placebo-controlled supplementation trial was conducted in lactating women who received placebo (n = 56), 75 μg I/d (n = 27), or 150 μg I/d (n = 26) after their infants' birth until 24 wk postpartum. Maternal and infant urine samples and breast-milk samples were collected at 1, 2, 4, 8, 12, 16, 20, and 24 wk. Maternal serum thyrotropin and free thyroxine concentrations were measured at 24 wk. RESULTS: Over 24 wk, the median urinary iodine concentration (UIC) of unsupplemented women and their infants ranged from 20 to 41 μg/L and 34 to 49 μg/L, respectively, which indicated iodine deficiency (ie, UIC < 100 μg/L). Mean maternal UIC was 2.1-2.4 times higher in supplemented than in unsupplemented women (P < 0.001) but did not differ significantly between the 2 supplemented groups. BMIC in the placebo group decreased by 40% over 24 wk (P < 0.001) and was 1.3 times and 1.7 times higher in women supplemented with 75 μg I/d (P = 0.030) and 150 μg I/d (P < 0.001), respectively, than in unsupplemented women. Thyrotropin and free thyroxine did not differ significantly between groups. CONCLUSION: BMIC decreased in the first 6 mo in these iodine-deficient lactating women; supplementation with 75 or 150 μg I/d increased the BMIC but was insufficient to ensure adequate iodine status in women or their infants. The study was registered with the Australian New Zealand Clinical Trials Registry as ACTRN12605000345684
Sediment transport-based metrics of wetland stability
Despite the importance of sediment availability on wetland stability, vulnerability assessments seldom consider spatiotemporal variability of sediment transport. Models predict that the maximum rate of sea level rise a marsh can survive is proportional to suspended sediment concentration (SSC) and accretion. In contrast, we find that SSC and accretion are higher in an unstable marsh than in an adjacent stable marsh, suggesting that these metrics cannot describe wetland vulnerability. Therefore, we propose the flood/ebb SSC differential and organic-inorganic suspended sediment ratio as better vulnerability metrics. The unstable marsh favors sediment export (18mgL(-1) higher on ebb tides), while the stable marsh imports sediment (12mgL(-1) higher on flood tides). The organic-inorganic SSC ratio is 84% higher in the unstable marsh, and stable isotopes indicate a source consistent with marsh-derived material. These simple metrics scale with sediment fluxes, integrate spatiotemporal variability, and indicate sediment sources
Global sensitivity analysis of a filtration model for submerged anaerobic membrane bioreactors (AnMBR)
The results of a global sensitivity analysis of a filtration model for submerged anaerobic MBRs (AnMBRs) are assessed in this paper. This study aimed to (1) identify the less- (or non-) influential factors of the model in order to facilitate model calibration and (2) validate the modelling approach (i.e. to determine the need for each of the proposed factors to be included in the model). The sensitivity analysis was conducted using a revised version of the Morris screening method. The dynamic simulations were conducted using long-term data obtained from an AnMBR plant fitted with industrial-scale hollow-fibre membranes. Of the 14 factors in the model, six were identified as influential, i.e. those calibrated using off-line protocols. A dynamic calibration (based on optimisation algorithms) of these influential factors was conducted. The resulting estimated model factors accurately predicted membrane performance.This research work has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO, Projects CTM2011-28595-C02-01/02) jointly with the European Regional Development Fund (ERDF) which are gratefully acknowledged.Robles Martínez, Á.; Ruano García, MV.; Ribes Bertomeu, J.; Seco Torrecillas, A.; Ferrer, J. (2014). Global sensitivity analysis of a filtration model for submerged anaerobic membrane bioreactors (AnMBR). Bioresource Technology. 158:365-376. https://doi.org/10.1016/j.biortech.2014.02.087S36537615
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