Sustainability assessment of municipal solid waste management requires a holistic approach in evaluating the impacts of current technology and processes. In this study, the sustainability analysis of the Municipal Solid Waste (MSW) incineration plant in Baltimore city was performed to determine its environmental, economic, and social impacts. The city’s major waste-to-energy generation plant has benefitted the city of Baltimore since inception till date in terms of waste processing, resulting in electricity and steam production for more than 40,000 homes and over 200 businesses. The life cycle impact of the incineration plant was analyzed using the Simapro life cycle assessment (LCA) software with the Building for Environmental and Economic Sustainability (BEES) database for correlation. The results obtained upon analysis show larger values of Global Warming Potential and eutrophication potential as 6.46 × 108 Gg of CO2 equivalence and 2.27 × 106 Gg N equivalence, respectively. These values resulted from the higher amount of fossil CO2 and NOx emitted from the plant. The acidification potential of 1.66 × 1017 H+ mmole eq resulted from the SO2 emitted by the incineration plant. The incineration plant exceeded the limitations set by the Environmental Protection Agency (EPA) on NOx (150 ppm), which is detrimental to the well-being of people as shown by this study. Installing an improved processing technology such as a Selected Catalytic Reactor (SCR) can drastically reduce the NOx emission to 45 ppm. Life Cycle Assessment was confirmed suitable in evaluating the environmental impacts of the MSW-to-energy treatment approach.

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The present study investigated the effect of operating parameters in modeling the output quality of welding process of steel sample. A three factor, three levels Box-Behnken Design (BBD) of RSM was applied to determine the effects of three independent variables (welding speed (A), welding current (B) and electrode potential (C)) on the tensile strength and to also develop a model for predicting the output quality. Data analysis shows that A, C, AB, BC, A2, B2and C2are the terms which significantly affected the ultimate tensile strength of the sample at 95% confidence level. The experimental values were very close to the predicted values and were not statistically different at p<0.05. The maximum tensile strength of 228 MPa was obtained at 250 A current, electrode diameter of 3.25 mm and 50 cm/min welding speed, respectively. The regression model obtained has provided a basis for selecting optimum process parameters for the improving output quality (tensile strength) of the welded steel sample.

Increasing production of poultry litter, and its associated problems, stimulates the need for generating useful energy in an environmentally friendly and efficient energy system, such as the use of shell-and-tube heat exchangers (STHE) in a fluidized-bed combustion (FBC) system. A holistic approach which involves the integration of the First Law of Thermodynamics (FLT) and Second Law of Thermodynamics (SLT) is required for conducting effective assessment of an energy system. In this study, the STHE designed by the CAESECT research group, which was integrated into the lab-scale FBC, was investigated to determine the maximum available work performed by the system and account for the exergy loss due to irreversibility. The effects of varying operating parameters and configuration of the space heaters connected to the STHE for space heating purposes were investigated in order to improve the thermal efficiency of the poultry litter-to-energy conversion process. Exergy and energy analysis performed on the STHE using flue gas and water media showed higher efficiency (75–92%) obtained via energy analysis, but much lower efficiency (12–25%) was obtained when the ambient conditions were factored into the exergy analysis, thus indicating huge exergy loss to the surroundings. From the obtained experimental data coupled with the simulation on parallel arrangement of air heaters, it was observed that exergy loss increased with increasing flue gas flow rate from 46.8–57.6 kg/h and with increasing ambient temperature from 8.8 °C to 25 °C. To lower the cost of STHE during final design, a larger temperature difference between the hot and cold flue gas is needed throughout the exchanger, which further increases the exergetic loss while maintaining an energy balance. In addition, this study also found the optimal conditions to reduce exergy loss and improve energy efficiency of the designed STHE. This study shows the possibility to evaluate energy systems using integration of exergy and energy analysis.