Permeability and Leaching Behavior of Cement Solidified/Stabilized Sludge Using Calcium-Bentonite as Additive

摘要

Experiments were conducted to stabilize the inorganic and organic pollutants from wastewatertreatment sludge (WWTS) using Portland cement as binder and calcium-bentonite as additive. Permeability and leaching behavior of heavy metals i.e. Zn and Cu, and organics in solidified WWTS were analyzed to assess the feasibility to immobilize types of contaminants, all determined on the basis of flexible wall permeability test. Influences of environmental impact on the immobilization of pollutants from WWTS were considered by varying acid condition of the influent and by using glucose as influent to stimulate microbial activity in the WWTS. Results of the study show that increasing calcium-bentonite content in the solidified WWTS leads to reduction of permeability and leaching of zinc and copper from test specimens, due to the formation of monolithic solidified product. However, Increase of acidity in the influent with neutral water, 0.05mol/L H+ and 0.1mol/L H+, permeability of test specimens increases at first and then decreases, obtaining the highest one permeated with solution of 0.05mol/L H+, and the smallest one with solution of 0.1mol/L H+. The similar results found in the leaching of pollutants from test specimens. Glucose has insignificant effect on the permeability comparing with water as influent, which may be due to the high alkalinity in the specimen inhibiting microorganism activity in the WWTS.