Physicochemical and FTIR spectroscopic analysis of fine fraction from a municipal solid waste dumpsite for potential reclamation of materials.

Improper municipal solid waste management in the past has landed most of this waste in open dumps of India. This dumped waste has a negative effect on the environment and human health and needs to be reclaimed either for material/energy recovery or to create space for future waste management. Since nearly half of the waste in dumpsites can be classified as fine fraction, in-depth knowledge of its characteristics is required to reclaim these dumpsites successfully. In this study, we characterize fine fraction, <4 mm, aged 1-10 years old, obtained from Mulund dumpsite in Mumbai, using physicochemical and spectroscopic analysis. The study also highlights different valorization routes to reclaim the fine fraction. The fine fraction was ~45% in the dumpsite and increased with the age of the waste. Visual inspection revealed that fine fraction older than five years was relatively homogeneous compared with younger fine fraction. Furthermore, pH (7.4-7.8) and electrical conductivity (0.70-1.92 mS cm-1) of the fine fraction met the Indian MSW compost standards; however, heavy metal levels were higher than the proposed standards. The fine fraction also had a high concentration of metals like aluminium (11 g kg-1) and iron (78 g kg-1), indicating metal recovery potential. Furthermore, Fourier Transform Infrared Spectroscopy results show that the fine fraction had dominant inorganic peaks and became relatively homogeneous with age. The study proposes fine fraction use as a secondary resource; however, some prior treatment would be required based on the application.

Effects of well spacing on geological storage site distribution costs and surface footprint.

Geological storage studies thus far have not evaluated the scale and cost of the network of distribution pipelines that will be needed to move CO(2) from a central receiving point at a storage site to injection wells distributed about the site. Using possible injection rates for deep-saline sandstone aquifers, we estimate that the footprint of a sequestration site could range from <100 km(2) to >100,000 km(2), and that distribution costs could be <$0.10/tonne to >$10/tonne. Our findings are based on two models for determining well spacing: one which minimizes spacing in order to maximize use of the volumetric capacity of the reservoir, and a second that determines spacing to minimize subsurface pressure interference between injection wells. The interference model, which we believe more accurately reflects reservoir dynamics, produces wider well spacings and a counterintuitive relationship whereby total injection site footprint and thus distribution cost declines with decreasing permeability for a given reservoir thickness. This implies that volumetric capacity estimates should be reexamined to include well spacing constraints, since wells will need to be spaced further apart than void space calculations might suggest. We conclude that site-selection criteria should include thick, low-permeability reservoirs to minimize distribution costs and site footprint.