Abstract
In order to develop an intelligent system for operating bioreactor landfills, methods are needed to measure water in situ, since water often limits waste degradation and must be added to landfills. In addition, models are needed to describe the simultaneous movement of gas and water through refuse. These two topics are the focus of my work. The partitioning gas tracer test for measuring water in refuse was advanced in my research, with results recently published in Environmental Science & Technology (Han, B., et al., 2007). In order to develop models for the simultaneous movement of gas and water through refuse, the influence of gas on water flow and water on gas flow must be described. The relative permeability-water saturation-capillary pressure relationship is proposed to describe these influences and will be measured for refuse at different degrees of waste compaction. While such measurements are common for soils, to the best of our knowledge these measurements will be the first of their kind for refuse.
An experimental column (61 cm long with 29 cm ID) was built based on similar testing procedures developed for soils (Hopmans, et al., 1998). Here, Hopmans’ original design was modified to (1) increase the volume of the waste sample, to account for the heterogeneity of refuse; (2) allow for varying degrees of waste compaction; and (3) allow both steady state and transient techniques, i.e., the multi-step outflow procedure, to be used. Tests and subsequent modifications to this laboratory experimental system were completed in the last four months. The experimental cell is now being used to measure the relative permeability-water saturation-capillary pressure relationship for various types of refuse for a range of compaction densities. Once mathematical descriptions are developed to fit these data, these equations will be incorporated into computer models for describing the movement of gas and water in bioreactor landfills.
In order to develop an intelligent system for operating bioreactor landfills, methods are needed to measure water in situ, since water often limits waste degradation and must be added to landfills. In addition, models are needed to describe the simultaneous movement of gas and water through refuse. These two topics are the focus of my work. The partitioning gas tracer test for measuring water in refuse was advanced in my research, with results recently published in Environmental Science & Technology (Han, B., et al., 2007). In order to develop models for the simultaneous movement of gas and water through refuse, the influence of gas on water flow and water on gas flow must be described. The relative permeability-water saturation-capillary pressure relationship is proposed to describe these influences and will be measured for refuse at different degrees of waste compaction. While such measurements are common for soils, to the best of our knowledge these measurements will be the first of their kind for refuse.
An experimental column (61 cm long with 29 cm ID) was built based on similar testing procedures developed for soils (Hopmans, et al., 1998). Here, Hopmans’ original design was modified to (1) increase the volume of the waste sample, to account for the heterogeneity of refuse; (2) allow for varying degrees of waste compaction; and (3) allow both steady state and transient techniques, i.e., the multi-step outflow procedure, to be used. Tests and subsequent modifications to this laboratory experimental system were completed in the last four months. The experimental cell is now being used to measure the relative permeability-water saturation-capillary pressure relationship for various types of refuse for a range of compaction densities. Once mathematical descriptions are developed to fit these data, these equations will be incorporated into computer models for describing the movement of gas and water in bioreactor landfills.