Materials and methods
2.1. Soil preparation
Sewage sludge from Lodz Municipal Wastewater
Treatment Plant (LM WWTP) and sediments from the
Sokoło´wka Sequential Biofiltration System (SSBS) were
collected. The Sokoło´wka Sequential Biofiltration System
was constructed in the upper section of the Sokoło´wka
River in order to remove sediments, suspended solids,
particulate pollutants, petroleum hydrocarbons, heavy
metals and nutrients from stormwater runoff through its
sedimentation and filtration mechanisms. The system
comprises three different zones: the zone of hydrodynamically
intensified sedimentation, the zone of intensive
biogeochemical processes and the zone of intensive
biofiltration. The sediment samples used in the experiment
were collected from the first zone wherein the accelerated
sedimentation of suspended matter and pollutants associated
with it occurs.
The sewage sludge and sediment samples were dried at
70 8C for 72 h then homogenized into small particles using
a mortar and used as fertilizer for the soil samples for
cucumber planting. The vegetable potting soil (specified
for cucumber growth) used in the experiment was
collected from Hollas Sp. z o.o. Pasłe˛k.
Four treatments were used: a control C in which no
sludge or sediment was added, and three levels of addition,
1.8 g, 5.4 g and 10.8 g per flower pot. The first corresponds
to the dose of 3 tonnes ha1, the allowed dosage per year
by the Regulation of the Minister of Environment of 13 July
2010 on municipal sewage sludge (Dz.U. Nr 137/2010 r.,
poz. 924); the second is the permitted dose of
9 tonnes ha1 per 3 years applied on one occasion; and
the third, 18 tonnes ha1 is above the permitted level.
Treatments are designated by the numerical dose per pot
and the abbreviations SS for sewage sludge and SED for
sediment.
2.2. Plant material
Cucumber seeds (C. sativus L.) cv ‘‘Cezar’’ were
germinated in Petri dishes for 7 days and the seedlings
were planted into the control and sewage sludge- or
sediment-amended soil. They were grown in a growth
chamber at of 23 0.5 8C with 16 h light/8 h dark cycle and
with 150 mmol m2 s1 photon flux density during the light
period, and 60% relative humidity. Five-week-old plants with
five fully expanded leaves were used for subsequent analysis.
A. 76 Wyrwicka et al. / Ecohydrology & Hydrobiology 14 (2014) 75–82