Partitioning Gas Tracer Tests for Measurement of Water in Municipal Solid Waste

Abstract

A key component in the operation of almost all bioreactor landfills is the addition of water to maintain optimal moisture conditions. To determine how much water is needed and where to add it, in situ methods are required to measure water within solid waste. Existing technologies often result in measurements of unknown accuracy, because of the variability of solid waste materials and time-dependent changes in packing density, both of which influence most measurement methods. To overcome these problems, a new technology recently developed by hydrologists for measuring water in the vadose zone-the partitioning gas tracer test-was tested. In this technology, the transport behavior of two gas tracers within solid waste is used to measure the fraction of the void space filled with water. One tracer is conservative and does not react with solids or liquids, while a second tracer partitions into the water and is separated from the conservative tracer during transport. This technology was tested in four different solid waste packings and was capable of determining the volumetric water content to within 48% of actual values, with most measurement errors less than 15%. This technology and the factors that affect its applicability to landfills are discussed in this paper.

Review of state of the art methods for measuring water in landfills

“…Because the tracers are separated ''chromatographically'' in time due to the influence of water, the difference in mean arrival times is a measure of the fraction of the pore space occupied by water, i.e., S w . The methodology for computing the mean tracer arrival times from tracer breakthrough curves and then S w is discussed in Imhoff et al (2003).…”

“…In the last 5-10 years considerable effort has been expended on the development of sensors to measure moisture within landfills (e.g., Yuen et al, 2000;Gawande et al, 2003;Imhoff et al, 2003). While several different sensor systems have been laboratory-tested and deployed in bioreactor landfills throughout the world, a critical assessment of these sensors in light of their performance in the field is lacking.…”

Single-well experimental design for studying residual trapping of supercritical carbon dioxide

“…Partitioning tracer tests that are done between two wells are referred to as partitioning interwell tracer test (PITT). PITTs have been developed to detect crude oil (Cooke, 1971;Dean, 1971;Tang and Harker, 1991), measure water saturation (Imhoff et al, 2003;Li and Imhoff, 2005), and characterize and quantify nonaqueous phase liquid (e.g., NAPL) saturation Jin et al, 1995;Mariner et al, 1999;Nelson et al, 1999;Whitley et al, 1999;Young et al, 1999). In PITT, tracers are injected upstream and the recovered tracer breakthrough curves (BTCs) at the downstream extraction well are used to analyze tracer retardation, which is used to infer phase saturation.…”

A Method for Measuring Moisture Content in Landfills Based on PGNAA Technique

“…Among them high concentration of salt can affect the growth and degradation of microorganisms. In recent years, considerable efforts have been devoted to developing set-ups to measure moisture content and element concentration in landfills [6][7][8][9].…”