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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/cm 3 whereas the real density is 2.12 g/cm 3 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.

This paper determined cations and anions concentrations, Total Kjeldahl Nitrogen (TKN), and heavy metals content in sewage sludge collected from the drying beds of wastewater treatment plant in Gaza. The aim was to test the possibility of using this sewage sludge as an alternative source of mineral fertilizers. Many instruments were used in this work: flame photometry (K, Na), EDTA titration (Ca, Mg), the turbidity method ( )

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Human activity puts pressures on coastal zone altering dissolved organic matter quality. No specific self-differentiating fluorescence signal of the anthropogenic DOM in the coastal zone is found in the literature. Solar irradiation were conducted on mixed samples of River water, sea water, wastewater treatment plant effluent. Excitation Emission Matrices of Fluorescence were used to monitor the fate of wastewater treatment plant effluent. Multilinear regression of CP/PARAFAC components contribution depending on mixing composition were done and was excellent. Kinetics of decreasing contribution versus irradiation time were investigated. Second order Kinetics were found for C1 and C2. Distinction between fluorescence signal of endmembers was undoable. Wastewater treatment plant endmember after photodegradation was highly predominant.

Organic matter has an important role in biogeochemistry in aquatic environments. This study investigated impact of suspended particulate organic matter (SPOM) on fluorescence signal of mixtures of three water types (River water RW, Sea water SW, effluent wastewater WW) using three-dimensional excitation emission fluorescence spectroscopy (3D-EEMs) and Parallel factor analysis PARAFAC and multilinear regression. Four irradiation experiments (Exp.1, Exp.2, Exp.3 and Exp.4) were conducted during different times of year ( two in autumn, one in winter and one in spring season). Samples were exposed to natural sunlight on laboratory rooftop in University of Toulon, France, with another set of samples were kept in dark as control samples. Three components (C1,C2, C3) model was validated by split-half and Concordia from the whole EEM dataset of all irradiation experiments. No protein-like fluorophores or PARAFAC components was found. The study revealed the effect of SPOM presence/absence on fluorescence signal of DOM and on resulting parameters of multilinear regression MLR model and kinetic constant of these MLR parameters. Kinetic constant (k) for all MLR coefficients was in order of greatness as Exp.1 (SPOM of WW only in mixtures ) > Exp.3 (SPOM of SW only in mixtures ) > Exp.2 (SPOM of RW only in mixtures )> Exp.4 (All SPOM of RW, SW,WW in mixtures ) indicating that SPOM of WW is the most resistant to photodegradation. For dark control samples, only relative standard deviation RSD could be calculated from dataset. RSD values for C3 were the highest indicating its chaotic variations and the lowest RSD values were found for both C1 and C2 for all experiments. Statistical differences has been found between control and irradiated experiments. These models developed in this study can be used to predict fluorescence signal of anthropogenic effluent DOM during its transport in river systems to coastal zone.

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