An experimental study on fermentative H2 production from food waste as affected by pH.

Batch dark fermentation experiments were performed on food waste and mixtures of food waste and wastewater activated sludge to evaluate the influence of pH on biological H2 production and compare the process performance with and without inoculum addition. The effect of a preliminary thermal shock treatment of the inoculum was also investigated as a means to harvest the hydrogenogenic biomass. The best performance in terms of both H2 generation potential and process kinetics was observed at pH=6.5 under all experimental conditions (no inoculum, and untreated or thermally treated inoculum added). H2 production from food waste was found to be feasible even without inoculum addition, although thermal pre-treatment of the inoculum notably increased the maximum production and reduced the lag phase duration. The analysis of the fermentation products indicated that the biological hydrogen production could be mainly ascribed to a mixed acetate/butyrate-type fermentation. However, the presence of additional metabolites in the digestate, including propionate and ethanol, also indicated that other metabolic pathways were active during the process, reducing substrate conversion into hydrogen. The plateau in H2 generation was found to mirror the condition at which soluble carbohydrates were depleted. Beyond this condition, homoacetogenesis probably started to play a role in the degradation process.

Molten carbonate fuel cells fed with biogas: combating H(2)S.

The use of biomass and waste to produce alternative fuels, due to environmental and energy security reasons, is a high-quality solution especially when integrated with high efficiency fuel cell applications. In this article we look into the coupling of an anaerobic digestion process of organic residues to electrochemical conversion to electricity and heat through a molten carbonate fuel cell (MCFC). In particular the pathway of the exceedingly harmful compound hydrogen sulphide (H(2)S) in these phases is analysed. Hydrogen sulphide production in the biogas is strongly interrelated with methane and/or hydrogen yield, as well as with operating conditions like temperature and pH. When present in the produced biogas, this compound has multiple negative effects on the performance and durability of an MCFC. Therefore, there are important issues of integration to be solved. Three general approaches to solve the sulphur problem in the MCFC are possible. The first is to prevent the formation of hydrogen sulphide at the source: favouring conditions that inhibit its production during fermentation. Secondly, to identify the sulphur tolerance levels of the fuel cell components currently in use and develop sulphur-tolerant components that show long-term electrochemical performance and corrosion stability. The third approach is to remove the generated sulphur species to very low levels before the gas enters the fuel cell.

[Tuberculosis control in Senegal: update on care services and recommendations for improvement]. / La lutte contre la tuberculose au Sénégal: situation actuelle de la prise en charge et recommandations pour son amélioration.

The goal of this study was to evaluate tuberculosis control in Senegal especially with regard to organization, quality, and availability of care services. Study was carried out from January to October 2002 within the framework of the National Turberculosis Control Program (NTCP) in 10 public hospitals and 8 private facilities including 4 doctors' offices, 2 company medical dispensaries, and 2 medical laboratories. Case observations were collected at the same time as surveying of diagnostic and therapeutic departments. In addition NTCP records for the period from 2000 to 2001 were searched. The reporting rate of new cases confirmed by positive smears is still low in Senegal, (62/100 000 inhabitants). Reporting is particularly low in rural areas where a clear-cut male predominance was observed. The cure rate also remains low (mean, 62%) mainly due to failure to complete treatment (28%). This situation contrasts with the extensive resources that have been devoted to diagnosis and treatment including field units for diagnosis (76 laboratories) and treatment (68 centers). These facilities are well integrated into the healthcare system and distributed nation-wide and provide effective care free of charge. The findings of this study demonstrate that there are serious impediments to control of tuberculosis in Senegal. Recommendations are made at various levels based on the results of problem analysis and are used to develop new management strategies aimed at improving NTCP performance indicators in Senegal.