Environmental impact and optimization of lake dredged-sludge treatment and disposal technologies based on life cycle assessment (LCA) analysis

Abstract

Baiyangdian Lake is the most important natural water body in North China and is having a dredging project to remediate serious endogenous pollution from sediments. How to reduce the secondary environmental impact in the process of dredged-sludge treatment and disposal is of great significance. Four typical dredged-sludge treatment technologies were evaluated based on comprehensive life cycle environmental and economic analysis in this paper, and recommendations are put forward to selecting suitable treatment technology for dredged-sludge with heterogeneous pollution. The LCA results indicated that land use process is a preferable approach for less polluted dredged-sludge due to simple steps and low cost. However, the environmental burden derived from land use will obviously increase with the extent of the dredged-sludge pollution, especially depends on the content of heavy metals. Comparatively, organochlorine pesticides in dredged-sludge generate a negligible environmental impact because of their trace concentration. Besides, the manufacture of non-fired brick or water storage clay is an effective treatment technology for dredged-sludge with high pollution to reduce toxic environmental impacts owing to the immobilization and stabilization of heavy metals, although it has high economic costs and consumes a large amount of energy and materials. Moreover, it is worth noting that polyacrylamide may be not an excellent conditioner for dredged-sludge dewatering because of the apparent contribution to human toxicity and freshwater aquatic ecotoxicity impact. Overall, this study highlighted and concluded how to select and optimize the adoption of suitable technologies to reduce environmental risks generated from the treatment and disposal of dredged-sludge.