Controlling Biomass Ash Alkalinity for Land Application.

摘要

Burning biomass wastes generates large quantities of ash products which contain plant nutrients, such as Ca, Mg, K, and P. These nutrients could be returned for reforestation. However, the ash high alkalinity presents some challenges in terms of direct land application. The high alkalinity affects the leachability of various ash components and adversely affects ground vegetation. In this thesis, it will be shown that CO2 can effectively decrease ash alkalinity at room temperature. From the study, it was found that the rate carbonation depends heavily on the moisture content of the ash and the CO2 partial pressure. From a practical point of view, a combined process of ash pelletization and carbonation was tested to have some potential for industrial application. It was found that the time required for carbonation equals the time it takes for the wetted pellet, regardless of the size, to dry at 15 vol% of CO2.