This study covers a thorough characterisation of landfill leachates
emerging from a sanitary landfill area. The landfill leachates were obtained
in the acidic stage of landfill stabilisation. Their organic content was high
as reflected by the high BOD5 (5 day biological oxygen demand)
and COD (chemical oxygen demand) values. They were also highly polluted in
terms of the parameters TKN (total Kjeldahl nitrogen), NH4-N,
alkalinity, hardness and heavy metals. Nickel was present in these wastewaters
at a significant concentration. With regard to the high heavy metal content
of these wastewaters, several physicochemical removal alternatives for the
heavy metals Cu, Pb, Zn, Ni, Cd, Cr, Mn and Fe were tested using coagulation,
flocculation, precipitation, base addition and aeration. Additionally, COD
removal and ammonia stripping were examined. Co-precipitation with either
alum or iron salts did not usually lead to significantly higher heavy metal
removal than lime alone. The major methods leading to an effective heavy metal
removal were aeration and lime addition. Nickel and cadmium seemed to be strongly
complexed and were not removed by any method. Also lead removal proved to
be difficult. The results are also discussed in terms of compliance with standards.
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