Comparing the Efficacy Rates of Lime and Poly Aluminum Chloride Coagulants in Cadmium Removal from the Landfill Leachate by Chemical Precipitation

Document Type : Original Article


1 Environmental Health Department, Health Faculty, Kashan University of Medical Sciences, Kashan, Iran

2 Social Determinants of Health (SDH) Research Center” and “Environmental Health Department, Health Faculty”, Kashan University of Medical Sciences, Kashan, Iran


Aims Chemical precipitation is a simple, efficient, and cost-effective method for eliminating
heavy metals found in landfill leachate. The aim of the present study was to compare the
efficacy rates of cadmium removal with the coagulants like poly aluminum chloride and lime
using chemical precipitation method.
Materials & Methods In this experimental study, the raw studied samples were collected
from the landfill located in Kahrizak, Iran, in May 2014. The elimination rates of cadmium
at 1000, 1500 and 2000mg/l concentrations of lime; at 100, 150 200mg/l concentrations of
poly aluminum chloride; at 7, 9, 11 pH levels; and during 20, 40 and 60min of the reaction
time were studied. Data were analyzed in SPSS 16 software using ANOVA, independent T and
repeated measurement tests.
Findings The maximum elimination rate of cadmium in both lime and poly aluminum
chloride were seen at pH=11. The maximum rates of cadmium removal occurred at minute
40 in 2000mg/l concentration of lime (99.4%) and 200mg/l concentration of poly aluminum
chloride (98%).
Conclusion Both lime and poly aluminum chloride have the best cadmium removal rate from
leachate at pH=11 after 40 minutes of precipitation process. Being more inexpensive and
easily available than poly aluminum chloride, lime is considered as an appropriate coagulant.