CHARACTERIZATION OF ASPEN ASH, SAND AND LOG-YARD WASTE MIXTURES FROM AN ASPEN-BASED ORIENTED STRAND BOARD MILL FOR USE AS AN INTERMEDIATE LANDFILL COVER

摘要

Wood ash has a variety of uses including land application, geotechnical construction and daily and final covers for landfills. The objective of this study was to determine the relevant chemical and physical properties of selected mixtures of aspen burner-ash, log-yard waste scrapings (sandy soil plus wood waste) and a sandy soil as an intermediate landfill cover. The treatment mixtures, per weight basis, included: (1) 100% sand; (2) 80/20 log-yard waste/ash; (3) 50/50 sand/ash; (4) 40/30/30 sand/log-yard waste/ash; (5) 60/40 ash/log-yard waste; (6) 100% ash; (7) 100% log-yard waste. All treatments containing ash had a very high pH (12.8-13.3) and electrical conductivity (39-105 dS m~(-1)). The ash contained significant amounts of beneficial nutrients, but soil solution dominance by sodium carbonate suppressed concentrations of calcium and magnesium. Treatments containing ash showed lower bulk densities but relatively higher soil strength values (2.5-3.5 kg cm~(-2)) than that for the log-yard waste scrapings or the sandy soil, due to its self-cementing properties. Mixtures of soil material and ash had lower hydraulic conductivity rates (～1.0 x 10~(-4) cm s~(-1)) and lower infiltration rates compared to the sandy soil (～5 x 10~(-3) cm s~(-1)) or log-yard waste scrapings or pure ash. Water holding capacity increased with treatments containing ash. A soil-water balance model used to determine percolation rates through a 60 cm layer of treatment material showed that treatments containing a mixture of ash and soil material decreased the downward flow of water throughout the year.