Landfill gas generation after mechanical biological treatment of municipal solid waste. Estimation of gas generation rate constants

Mechanical biological treatment (MBT) of residual municipal solid waste (RMSW) was investigated with respect to landfill gas generation. Mechanically treated RMSW was sampled at a full-scale plant and aerobically stabilized for 8 and 15 weeks. Anaerobic tests were performed on the aerobically treated waste (MBTW) in order to estimate the gas generation rate constants (k,y(-1)), the potential gas generation capacity (L(o), Nl/kg) and the amount of gasifiable organic carbon. Experimental results show how MBT allowed for a reduction of the non-methanogenic phase and of the landfill gas generation potential by, respectively, 67% and 83% (8 weeks treatment), 82% and 91% (15 weeks treatment), compared to the raw waste. The amount of gasified organic carbon after 8 weeks and 15 weeks of treatment was equal to 11.01+/-1.25kgC/t(MBTW) and 4.54+/-0.87kgC/t(MBTW), respectively, that is 81% and 93% less than the amount gasified from the raw waste. The values of gas generation rate constants obtained for MBTW anaerobic degradation (0.0347-0.0803y(-1)) resemble those usually reported for the slowly and moderately degradable fractions of raw MSW. Simulations performed using a prediction model support the hypothesis that due to the low production rate, gas production from MBTW landfills is well-suited to a passive management strategy.     

The relationship between multiple levels of learning practices and objective and subjective organizational financial performance

Multi‐level learning approaches suggest that individuals, groups and organizations act both independently and interact dynamically to contribute to organizational performance. We directly examined this proposition in an Australian sample using a longitudinal design that employed subjective and objective financial performance data. Respondents completed a survey that provided details on their individual, team and organizational learning practices (ILP, TLP and OLP, respectively), and self assessed performance compared to 3 years ago. Concurrently, we collected objective performance data (sales/employee numbers) at 3 yearly intervals and averaged these data to create an index. Using hierarchical and moderated regression, we found a positive main effect for OLP with both subjective and objective performance. Main effects for ILP and TLP were not found. Further, we found a significant interaction between ILP and TLP such that the effect of TLP on productivity was better in organizations with less ILP. Three‐way interactions were not found. Overall, these results provide some support for the model. We discuss some limitations of the study and make recommendations for future studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Multivariate tools to investigate the spatial contaminant distribution in a highly anthropized area (Gulf of Naples,Italy)

Environmental Science and Pollution Research - The Gulf of Naples located in a high anthropized coastal area is subjected to an infrastructural intervention for the installation of a submarine...