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For many years gerontologic research has explored the construct of quality of life. Although quality of life is considered multidimensional, subjective, and an abstract individual perception, research tends to use established instruments with pre-determined parameters. Few studies touch directly on the subjective nature of quality of life. This research is based on a multidimensional model that defines quality of life as the perception an elder has about quality of life. Although the model has multiple indicators, this study focuses on the influence of two indicators, the confidant relationship and the attitude toward ones own aging, on an elder's self-rated quality of life. Data were gathered from 33 elders residing in two rural assisted living facilities. There was a significant positive relationship between quality of life and attitude toward aging, and the frequency of contact with the confidant and attitude toward aging. Although there was not a direct relationship between having a confidant and quality of life, it is possible that having a confidant influences one's attitude toward aging and attitude toward aging, in turn, influences quality of life.

The anaerobic digestion of the organic fraction of municipal solid wastes is taking increasing importance in the recent years. The main problem of some anaerobic digestion process is the large quantity of ammonia that is released, especially when high solid digestion is implemented. A fraction of the supernatant is treated and the remaining is recirculated to maintain the reactor in the optimum solids concentration. The question arising is if this recirculation stream should also be treated to improve biogas production. However, when doing the latter the quantity of ammonia inside the reactor increases too which could lead to inhibit the reactor operation. In this paper it appears that not only free ammonia affects the methanogenic fermentation but also ammonium ion concentration. Biogas production profiles are estimated using the Gompertz model. On the other hand, inhibition constants are fitted using a non-competitive inhibition model equation Thus, 50% inhibition of biomethane production was observed at level of 215 and 468 mg NH3_N/L under mesophilic and thermophilic conditions. However, the methane generation under mesophilic and thermophilic conditions was reduced by 50% when ammonium ion reach concentrations of 3,860 and 5,600 mg NH4+_N/L respectively. Under mesophilic conditions, pH higher than 7 impacted the methanogens bacteria negatively. This threshold pH limit, is variable under thermophilic conditions, depending on the total ammonia concentration. [ABSTRACT FROM AUTHOR]

This paper presents a comparison of dry anaerobic digestion reactors fed with differently sorted municipal organic solid wastes. One reactor was fed with source sorted organic wastes and a second reactor was fed with mixed organic wastes consisting of grey wastes, mechanically selected municipal solid wastes and sludge. The two reactors utilised the same process (Valorga) and operational conditions at full scale. The results of the study emphasise the influence of the kind of treated material on the process performances, especially in terms of biogas and methane production, thus, energy reclamation. The reactor treating the source sorted organic waste and the reactor treating the mixed organic wastes generated some 200 m³ and 60 m³ of biogas per ton of waste treated, respectively, while the specific methane production was some 0.40 and 0.13 m³CH4/kgTVS, respectively. The mass balance and the final fate of the digested material from the two reactors were also clearly different. As for the costs, these were some 29 € per ton of treated waste (50% for personnel) and 53 €/ton for disposing of the rejected materials. Incomes were some 100 €/ton (on average) and an other 15 €/ton came from green certificates. The initial investment was 16 million Euros. [ABSTRACT FROM AUTHOR]

The results of the start-up of two digesters in mesophilic and thermophilic conditions, together with its steady results at several organic loading rates are described. A kinetic study is also carried out which allows one to estimate the ultimate methane production, together with the first-order kinetic constant. Operation at thermophilic temperature yields better results as it allows a more loaded reactor and the methane production is slightly higher. [ABSTRACT FROM AUTHOR]