A comprehensive assessment of water quality in Fayoum depression, Egypt: identifying contaminants, antibiotic pollution, and adsorption treatability study for remediation

This study aimed to assess the current water quality status across various regions within the Fayoum depression by examining water canals, drains, and potential contaminants impacting public health and the local ecosystem. Additionally, an adsorption treatability investigation was conducted on various antibiotics identified during the assessment. Fifteen sampling points were selected across the Fayoum depression, covering surface water bodies and agricultural drainage systems during both winter and summer seasons. Physico-chemical, microbiological, and antibiotic analyses were performed on collected water samples. The water quality parameters investigated included pH, electrical conductivity, total dissolved solids (TDS), total coliforms, fecal coliforms, and concentrations of antibiotics such as ciprofloxacin and tetracycline. The findings revealed significant variations in water quality parameters among different water sources, categorizing them into three types: irrigation canals, polluted canals, and drains. High contamination levels were observed in certain water canals and drains due to untreated sewage and agricultural drainage discharge. Notably, elevated TDS levels (exceeding 1200 mg/L), microbial indicators count (with total coliforms reaching up to 2.3 × 106 CFU/100 mL), and antibiotics (with concentrations of ciprofloxacin and tetracycline exceeding 4.6 µg/L) were detected. To mitigate antibiotic contamination, a Phyto-adsorption treatability study using magnetite nanoparticles prepared with Phragmites australis plant extract demonstrated promising results, achieving complete removal of high antibiotic concentrations with an adsorption capacity of up to 67 mg/g. This study provides updated insights into water quality in the Fayoum depression and proposes a novel approach for addressing antibiotic contamination, potentially safeguarding human and environmental health.

resuspended in deionized water.The as-prepared Fe3O4 nanoparticles were stored under bench-top conditions until.

Characterization of Phyto-magnetite nanoparticle
The physico-chemical characterization of Phyto-magnetite was carried out in terms of Transmission electron microscopy (TEM), surface area, X-ray diffraction (XRD) and FTIR spectrometry.TEM micrographs were performed on JEOL JEM-2100 high resolution transmission electron microscope at an accelerating voltage of 200 kV, respectively.Samples for TEM were prepared by placing a droplet of colloid suspension in respective solvent on a Formvar carbon-coated, 300-mesh copper grid (Ted Pella) and allowing them to evaporate in air at ambient conditions.Fig. 2S shows TEM micrographes of the phyto-magntite nano-composite masses resemble structures in that they include spherical, uniform, and virtually regular pores and voids with diameters ranging from 3.5 to 4.9 nm.Selected area electron diffraction (SAED) showed a concentric circle with spots of diffraction scattered around the edges of a particular region.
Fig. 3S (a), XRD pattern and (b), FTIR of the prepared nanoparticles A surface area characteristic was carried out using Quantachrome (USA; Nova 2000 series) for N2 physisorption isotherm studies.Due to the presence of interparticle holes between the NPs, adsorption and desorption analysis of the fabricated Si NPs revealed a superior Brunauer-Emmett Teller (BET) surface area (186.5 m 2 /g), Barrett-Joyner-Halenda (BJH) surface area (129.7 m 2 /g), a total pore volume (0.54 cm 3 /g), and an average particle radius (1.92 nm).

Adsorption Study calculations
The adsorbed amount of antibiotic (qe) onto the developed nanocomposite adsorbent was calculated as shown in equation (1).
Where qe (mg/g) is the number of pollutants adsorbed per unit weight of the adsorbent at equilibrium.Ci and Cf are the initial and final nickel ion concentration.While V is the volume of the aqueous solution and m (g) represent the weight of the nano adsorbent.

Kinetic modelling and adsorption isotherms
Pseudo first order (PFO), and pseudo second order (PSO), models were used to analyze the adsorption processes.The linear form of the PFO, and PSO models were as follows (Eq.2-4), Pseudo first order: Pseudo Second order: Where qt and qe are connected to the quantity of TC and CIP adsorbed on per unit weight of Phyto-magnetite at time 't' and equilibrium, respectively.The constants KPFO and KPSO are in PFO, and PSO respectively.KPFO and KPSO D are estimated through the slope and intercept of the curves of plot of In(qe-qt) versus 't', t/qt versus 't' .The capacity of Phytomagnetite on TC and CIP sequestration was examined using isotherm models i.e.
Freundlich and Langmuir; the linear forms of the models are explained as follows (eq.4-5).

Freundlich isotherm:
Where, Ce and qe are the equilibrium concentration (mg/L) and equilibrium adsorption capacity (mg/g) of antibiotics, respectively.From the slope and intercept of log (qe) versus log (Ce), the Freundlich parameter values, 1/n and KF, were calculated.

Langmuir isotherm:
Where qm=maximum adsorption capacity of nanocomposite; KL= Langmuir equilibrium constant (L /mg).The Langmuir isotherm assumes that the adsorption of TC and CIP on the surface of Phyto-magnetite in the monolayer.The values of qm and KL were estimated through the slope and intercept of plots of 1/qe versus 1/Ce.

Fig. 4S
Fig. 4S Ca, Mg and K average concentration in different sampling sites (Group A, B, C) during summer and winter.

Fig. 5S
Fig. 5S Na, Cl and SO4 average concentration in different waster sampling sites (Group A, B, C) during summer and winter.

Table 1S
Regulations limits of chemical and biological parameters in irrigation canals and drains.

Table 2S
Results of physiochemical and metals parameters of the water sample sites inGroup A (SP1-SP6) during summer and winter.

Table 3S
Results of physiochemical and metals parameters of the water sample sites in Group B (SP8, SP10, SP12 and SP14) during summer and winter.

Table 5S
Fungal counts in different samples collected from canals and drains during summer and winter.
Fig. 6S Algae counts results for all collected samples during winter and summer.