Abstract
Monolayer barriers called evapotranspiration (ET) covers were developed as alternative final cover systems in waste landfills but high-quality soil remains a limiting factor in these cover systems. Coal bottom ash was evaluated to be a very good alternative to soil in previous tests and a combination of soil (65% wt.wt-1) and coal bottom ash (35% wt.wt-1) was evaluated to be the most feasible materials for ET cover systems. In our pot test, selected manure compost as soil amendment for the composite ET cover system, which was made of soil and bottom ash at ca. 40 Mg.ha-1 application level was very effective to promote vegetation growth of three plants; namely, garden cosmos (Cosmosbipinnatus), Chinese bushclover (Lespedezacuneata), and leafy lespedeza (Lespedeza cyrtobotrya). To evaluate the effect of compost application on plant growth in an ET vegetative cover system, two couples of lysimeters, packed with soil and a mixture of soil and bottom ash, were installed in a pilot landfill cover system in 2007. Manure composts were applied at the rates of 0 and 40 Mg.ha-11before sowing the five plant species, i.e.indigo-bush (Amorphafruticosa), Japanese mugwort (Artemisia princeps, Arundinella hirta, Lespedezacuneata, and Lespedezacyrtobotrya). Unseeded native plant (green foxtail,Setaria viridis) was dominant in all treatments in the 1st year after installation while the growth of the sown plants significantly improved over the years. Total biomass productivity significantly increased with manure compost application, and more significantly increased in the composite ET cover made of soil and bottom ash treatment compared to the single soil ET cover, mainly due to more improved soil nutrient levels promoting vegetation growth and maintaining the vegetation system. The use of bottom ash as a mixing material in ET cover systems has a strong potential as an alternative to fine-grained soils, and manure compost addition can effectively enhance vegetative propagation in ET cover systems.
Highlights
Landfills undergoing closure must be covered with a final cover that minimizes the long-term migration of liquids through the landfill [1]
Monolayer barriers called as evapotranspiration (ET) cover are covers that include a thick layer of fine-grained soil generally covered with a layer of vegetated topsoil and alternative final cover systems to the conventional cover system
Using a quadratic response model, the dry biomass yield of Cosmos bipinnatus in the composite ET cover that was made of bottom ash and soil was affected by the compost application rates as “Yield = 2234 + 94.7 Compost – 0.98 Compost2”, where compost application rate is expressed as Mg·ha−1
Summary
Landfills undergoing closure must be covered with a final cover that minimizes the long-term migration of liquids through the landfill [1]. The capping system can vary from simple soil cover to multiple layers of earthen and geosynthetic materials [2]. Several studies [3,4] have explored various alternative cover technologies for final closure of waste landfills. Monolayer barriers called as evapotranspiration (ET) cover are covers that include a thick layer of fine-grained soil generally covered with a layer of vegetated topsoil and alternative final cover systems to the conventional cover system. Lee et al / Journal of Agricultural Chemistry and Environment 2 (2013) 50-58
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