TITLE:
Physicochemical Properties of Sewage Sludge from Gaza
AUTHORS:
Ibrahim Y. El-Nahhal, Husam Al-Najar, Yasser El-Nahhal
KEYWORDS:
Sludge, Hydrophobicity, Bulk Density, Particle Size, Water Holding Capacity, Void Volume
JOURNAL NAME:
International Journal of Geosciences,
Vol.5 No.6,
May
8,
2014
ABSTRACT: This
study characterized the physicochemical properties of sewage sludge collected
from Gaza wastewater treatment plant. Sludge samples were collected from the
drying beds, air-dried, sieved through 2 mm and stored in plastic bags at room
temperature. Sludge density, particle size distribution, water holding
capacity, void volume, pH, EC, total organic carbon and hydrophobicity were
determined. Results showed the bulk density is about 1.18 g/cm3 whereas
the real density is 2.12 g/cm3 and void volume is 50%; Particle size distribution
showed that the major size of sludge is sand-like size (630 - 200 μm) and the
minor size is silt-like size (200 - 20 μm) and clay-like size is less than 20
μm. Sludge has an acidic pH reaction (6.78 ± 0.02) with an electric
conductivity equal to (2.49 ± 0.04) mS?cm-1. The
hydrophobicity of sludge is very high, water drop penetration time (WDPT) is
114.77 ± 18.78 sec with a radius of 0.44 ± 0.08 cm. In the way around, oil drop
penetration time (ODPT) of sludge is 5.05 ± 1.28 sec with a radius of 1.25 ± 0.14
cm. The WDPT/ODPM ration has very high value 22.73 indicating extreme
hydrophobicity. High value of hydrophobicity may reduce water filtration in
soil when sludge applied for agriculture. These results suggest that sludge
application to soil may change the physicochemical properties of soil.