Effectiveness of Coagulation in Contaminants Removal from Biologically Treated Landfill Leachate

The effectiveness of the coagulation process in removing contaminants from biologically treated leachates from a municipal waste landfill was investigated. The biologically treated leachates were characterized by a low concentration of NH4+-N (16.08 mg N L-1), and TKN (168 mg N L-1). The organic matter concentration, expressed as BOD (Biological Oxygen Demand) was 50 mg O-2 L-1, the concentration of hard-to-break COD (Chemical Oxygen Demand) organic compounds was 3390 mg O-2 L-1. The coagulation process was carried out in laboratory conditions, using variable doses of aluminium coagulants: polyaluminium chloride, aluminium sulphate, sodium aluminate and iron: iron (III) chloride. The maximum doses were 0.8-1.0 g Me L-1. The process was maintained between 5.93-6.97. The removal effect of the organic matter (COD) was obtained at 60-63% for aluminium coagulants and 37% for iron (III) chloride. The colour reduction occurred in 90% and the total phosphorus concentration was reduced to a maximum of 97%.