Where sedimentation tanks were present in the system, the
sediments were sampled from the bottom of these tanks, immediately
prior to the discharge pipe. At the other sites, samples
were collected from the leachate volume measurement points,
where sediments had collected, or, if necessary, sediment-rich
leachate collected from the bottom of the sedimentation tanks
was centrifuged (Beckman J2-21m centrifuge, 15,000 rpm for
10 min). After direct collection, or separation by centrifugation,
the samples were kept frozen until further processing. Where
sediments could be sampled directly, approximately 1.5–2 kg
of sediments (wet weight) was sampled, and further processed.
Where the sediment was collected from the leachate, approximately
100 g of sediment was separated from around 40 L of
sediment-rich leachate.