Novel approach on reduction in GHG emissions from sludge lime stabilization as an emergent and regional treatment in China

Abstract

As a typical organic solid waste, sludge plays an important role in contributing to greenhouse gas (GHG) emissions resulted by its treatment and disposal. As a temporary and emergent treatment measurement, sludge lime stabilization is regionally adopted in most sludge generated units in China. In present case, sludge lime stabilization system in China was productive of total GHG emissions, including indirect and direct emissions during lime stabilization and carbon reduction owing to lime synthesis and consumption, were first quantified respectively. The results indicated that electricity consumption was main component of indirect emissions, including mixing and transportation related mechanical equipment use. Direct emission was attributed to CO2 absorption during the second step in hydration reaction of lime stabilization. Meanwhile, a carbon credit portion of lime synthesis was also taken to the consideration of carbon budget. In brief, reduction in total replaceable carbon emission resulted by sludge lime treatment in comparison to landfill was calculated to be 0.8092 tCO2e·t−1. As treated production, lime-stabilized sludge is suggested to amend acidic soil for its revegetation. It is concluded that lime stabilization of sludge shows a significant GHG reduction effect despite of its temporary and emergent nature.