Hydrothermal carbonization (HTC) is a wet, low temperature thermal conversion process that continues to gain significant attention for the sustainable generation of value-added solid, liquid, and gas ...products from organic waste streams. Although it is well documented that both waste properties (e.g., elemental composition) and carbonization process conditions influence hydrochar properties, their specific influence on the total energy that can be recovered using HTC remains unclear. Non-linear random forest models were developed based on data collected from HTC-related literature to describe hydrochar yield and energy content, both of which are required to determine the total energy recovered in the hydrochar. Results indicate that total recoverable energy from organic wastes using HTC is correlated with feedstock carbon content; overall, the total energy content for feedstocks with carbon contents ranging from approximately 40 - 48% are similar. In addition, the total energy that can be recovered from the feedstock remains fairly constant when the initial solids concentrations are greater than 20%. Reaction time appears to have little influence on total recoverable energy from each feedstock at reaction times greater than approximately 150 min, while increases in reaction temperature result in a slight decline in total recoverable energy because of decreases in hydrochar yields at higher temperatures.
•Random forest models were used to determine the total energy recovered in the hydrochar.•Total recoverable energy in hydrochar is correlated with feedstock carbon content.•Recoverable energy from hydrochar is constant at solids concentrations greater than 20%.•Reaction time has little influence on recoverable energy at times greater than 150 min.•Maximize hydrochar yields to maximize total recoverable energy from hydrochar.
Couple relationship problems are common and associated with health problems. The aim of this study was to explore general practitioners' (GPs') experiences, expectations, and educational needs when ...dealing with couple relationship problems in consultations.
We conducted an exploratory qualitative study by carrying out 3 semistructured focus group interviews with 18 GPs. We used systematic text condensation for the analyses.
Participants shared their experiences of handling couple relationship problems in consultations. Three main themes emerged: (i) pragmatic case-finding: golden opportunities to reveal patients' couple relationship problems; (ii) conceptual and role confusion; (iii) professional competence and personal experience. While issues in relationships could serve as an explanation for relevant clinical problems, some GPs questioned whether relationship issues are strictly medical. All participants had engaged in individual supportive therapy, but none saw themselves as therapists. The interviews revealed that an individual supportive focus might lead to a consolidation of 1 partner's view, rather than challenging their position. Long-term doctor-patient relationships made it easier to talk about these issues.
This study revealed several paradoxes. GPs are confident in offering individual supportive therapy for couple relationship issues but should be aware of substantial pitfalls such as side-taking and constraining change. Despite dealing with relationship problems, GPs do not see themselves as therapists. They use professional and personal experience but would benefit from increasing their skills in cognitive restructuring promoting behavioural flexibility facing relationship problems.
Because effective operation of bioreactor landfills involves careful operation and construction of infrastructure beyond that necessary in traditional landfills, upfront capital and operating costs ...are greater than those associated with traditional landfills. Prior to investing in bioreactor landfills, landfill owners must be convinced that larger short-term expenses (e.g., liquid and/or air injection infrastructure) will be balanced by future economic benefits (e.g., extension of landfill life, reduced leachate treatment costs, etc.). The purpose of this paper is to describe an economic model developed to evaluate the impact of various operational (anaerobic, aerobic, or hybrid) and construction (retrofit and as-built) bioreactor landfill strategies on project economics. Model results indicate retrofit bioreactor landfills are more expensive than traditional landfills, while both the as-built and aerobic bioreactor landfills are less costly. Simulation results indicate the parameters that influence bioreactor economics most significantly are airspace recovery, gas recovery and subsequent use to generate electricity, and savings resulting from reduced leachate treatment costs.
Although bioreactor landfills have many advantages associated with them, challenges remain, including the persistence of NH
3-N in the leachate. Because NH
3-N is both persistent and toxic, it will ...likely influence when the landfill is biologically stable and when post-closure monitoring may end. An in situ nitrogen removal technique would be advantageous. Recent studies have shown the efficacy of such processes; however, they are lacking the data required to enable adequate implementation at field-scale bioreactor landfills. Research was conducted to evaluate the kinetics of in situ ammonia removal in both acclimated and unacclimated wastes to aid in developing guidance for field-scale implementation. Results demonstrate that in situ nitrification is feasible in an aerated solid waste environment and that the potential for simultaneous nitrification and denitrification (even under low biodegradable C:N conditions) in field-scale bioreactor landfills is significant due to the presence of both aerobic and anoxic areas. All rate data fit well to Monod kinetics, with specific rates of removal of 0.196 and 0.117
mg
N/day-g dry waste and half-saturation constants of 59.6 and 147
mg
N/L for acclimated and unacclimated wastes, respectively. Although specific rates of ammonia removal in the unacclimated waste are lower than in the acclimated waste, a relatively quick start-up of ammonia removal was observed in the unacclimated waste. Using the removal rate expressions developed will allow for estimation of the treatment times and volumes necessary to remove NH
3-N from recirculated landfill leachate.
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► High silica MFI zeolites show selective adsorption for p-cresol in solution. ► Adsorption isotherms in aqueous media performed containing BSA, and in vitro (HS). ► Zeolites to be ...applied without direct contact with serum albumin (ultra-filtrate). ► Completion of haemodialysis procedures by zeolite based selective adsorption units.
The removal of uremic toxins by zeolites is investigated in the context of the exploration of alternative methods to blood purification by dialysis. The case of a partially protein bound molecule, p-cresol, is studied here. High silica MFI type zeolites show a selective adsorption for p-cresol without major ion exchange with the cations present under equilibrium conditions in solution. Adsorption isotherms in different media were performed: pure water, artificial blood serum containing bovine serum albumin and human serum (HS obtained from a pool of 50 dialysis patients). p-Cresol elimination levels of 80–85% were obtained under in vitro conditions. However, in HS, p-cresol affinities for the zeolites are generally reduced as compared with pure water due to a partial obstruction of the pore system by adsorption of proteins on the external surface of zeolites particles. These results show that zeolites can be successfully employed as specific adsorbents for uremic toxins but without direct contact with serum albumin, which means only in the ultra-filtrate.
•Influence of changes in initial process water on carbonization were evaluated.•Changes in initial water pH and organic content influenced carbonization kinetics.•High concentrations of CaCl2 ...influenced carbonization mechanisms.•Initial process water pH and organics imparted little influence on carbonization.
Hydrothermal carbonization (HTC) is a thermal conversion process that has been shown to be environmentally and energetically advantageous for the conversion of wet feedstocks. Supplemental moisture, usually in the form of pure water, is added during carbonization to achieve feedstock submersion. To improve process sustainability, it is important to consider alternative supplemental moisture sources. Liquid waste streams may be ideal alternative liquid source candidates. Experiments were conducted to systematically evaluate how changes in pH, ionic strength, and organic carbon content of the initial process water influences cellulose carbonization. Results from the experiments conducted evaluating the influence of process water quality on carbonization indicate that changes in initial water quality do influence time-dependent carbonization product composition and yields. These results also suggest that using municipal and industrial wastewaters, with the exception of streams with high CaCl2 concentrations, may impart little influence on final carbonization products/yields.
•Hydrothermal carbonization data were collected from the literature.•Regression techniques were used to build statistical models.•Random forest models fit data better than other models.•Most ...influential parameters on hydrochar characteristics were determined.•Importance of model parameters on hydrochar properties change with process conditions.
Hydrothermal carbonization (HTC) is a wet, low temperature thermal conversion process that continues to gain attention for the generation of hydrochar. The importance of specific process conditions and feedstock properties on hydrochar characteristics is not well understood. To evaluate this, linear and non-linear models were developed to describe hydrochar characteristics based on data collected from HTC-related literature. A Sobol analysis was subsequently conducted to identify parameters that most influence hydrochar characteristics. Results from this analysis indicate that for each investigated hydrochar property, the model fit and predictive capability associated with the random forest models is superior to both the linear and regression tree models. Based on results from the Sobol analysis, the feedstock properties and process conditions most influential on hydrochar yield, carbon content, and energy content were identified. In addition, a variational process parameter sensitivity analysis was conducted to determine how feedstock property importance changes with process conditions.
Prx1 and Prx2 are closely related paired-class homeobox genes that are expressed in very similar patterns predominantly in mesenchyme. Prx1 loss-of-function mutants show skeletal defects in skull, ...limbs and vertebral column (Martin, J. F., Bradley, A. and Olson, E. N. (1995) Genes Dev. 9, 1237â1249). We report here that mice in which Prx2 is inactivated by a lacZ insertion had no skeletal defects, whereas Prx1/Prx2 double mutants showed many novel abnormalities in addition to an aggravation of the Prx1 single mutant phenotype. We found defects in external, middle and inner ear, reduction or loss of skull bones, a reduced and sometimes cleft mandible, and limb abnormalities including postaxial polydactyly and bent zeugopods. A single, or no incisor was present in the lower jaw, and ectopic expression of Fgf8 and Pax9 was found medially in the mandibular arch. A novel method to detect β-galactosidase activity in hydroxyethylmethacrylate sections allowed detailed analysis of Prx2 expression in affected structures. Our results suggest a role for Prx genes in mediating epitheliomesenchymal interactions in inner ear and lower jaw. In addition, Prx1 and Prx2 are involved in interactions between perichondrium and chondrocytes that regulate their proliferation or differentiation in the bones of the zeugopods.
The goal of this study was to use life cycle assessment to evaluate whether using liquid hazardous waste as an alternative fuel source in cement manufacturing processes located in the United States ...improves system environmental impact when compared with a facility using coal. Results from this study indicate that replacing coal with hazardous waste reduces the environmental impacts associated with the global warming impact, acidification impact, and freshwater ecotoxicity, while the human toxicity impacts for cancer and eutrophication-related environmental impacts increase. Reducing grid purchased electricity by recuperating waste heat from the process, cooling the exhaust gases and generating electricity to offset electrical demand, could reduce environmental impacts associated with off-site grid purchased electricity and should be considered for further environmental impact reductions. In addition, these results confirm that there are certain positive environmental effects associated with the co-burning of hazardous waste during cement manufacturing and replacing fossil fuels, such as coal, with high energy content hazardous waste.
•Replacing coal with hazardous waste reduces some environmental impacts.•Using hazardous waste increases human toxicity and eutrophication impacts.•Results confirm positive environmental effects with the co-burning of hazardous waste.
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