In the current study, a comparison between the diferent Mn3O4/ZnO, CuO/ZnO and Fe2O3/ZnO nanocomposites with respect to their structural, morphological, optical and photocatalytic properties is presented. The nanostructure nature of the investigated composites was confrmed by the XRD and SEM analysis. The nanocrystalline ZnO, M3O4, CuO and Fe2O3 phases were observed with diferent crystalline structure, including hexagonal, tetragonal, monoclinic and rhombohedral, respectively. The morphology of ZnO based nanocomposites was found to be dependent on the type of the metal oxide added to ZnO nanostructure. In addition, the studied nanocomposites showed diferent optical properties. The highest and lowest band gap of 3.14 and 2.00 eV were obtained for ZnO nanoparticles and Fe2O3/ZnO nanocomposite. Concerning the photocatalytic properties, the ZnO nanoparticles, Mn3O4/ZnO, CuO/ZnO and Fe2O3/ZnO nanocomposites showed an efciency of 49.63, 29.8, 11.61 and 95.34%, respectively, for the photodegradation of methylene blue. The Fe2O3/ZnO nanocomposites exhibited the highest activity for water purifcation compared to the other nanocomposites

This study investigated the bioelectrical performance of a single-chamber microbial fuel cell (SCMFC) fueled with acetate as the electron donor and inoculated with municipal solid waste rejected fractions (MSWRFs) as a microbial inoculum. The molecular characterization of the bacterial community structures of the anodic biofilm was conducted based on 16s RNA gene sequencing. The results indicated that the highest open-circuit voltage (OCV) was 797 mV and the system had a maximum power density of 134.5 mW/m2 at a stable current density of 328 mA/m2 . The microbial fuel cell’s (MFC) columbic efficiency (CE) was 55% at a maximum substrate degradation rate of about 86.6% based on COD removal efficiency. The molecular analysis of the anodic bacterial isolates indicated that the phylogenetic bacterial mixture was dominated by seven strains with similarity percentage above 99% for each strain: Enterococcus faecalis, Clostridium butyricum, Bacillus sp., Bacillus subterranous, Enterobacter celoaca, Klebsiella pneumonia, and Escherichia coli. These results suggested that MSWRFs bacterial consortia have a moderate symbiotic structure as indicated by electrons release in parallel with substrate decomposition.

This study aimed to evaluate the capacity of different inoculum sources and their bacterial diversity to generate hydrogen (H₂). The highest Simpson (0.7901) and Shannon (1.581) diversity indexes for H₂-producing bacterial isolates were estimated for sewage inocula. The maximum cumulative H₂ production (H_max) was 639.6 ± 5.49 mL/L recorded for the sewage inoculum (SS30) after 72 h. The highest H₂-producing isolates were recovered from SS30 and identified as Clostridium saccharobutylicum MH206 and Lactobacillus brevis MH223. The H_max of C. saccharobutylicum, L. brevis, and synergistic coculture was 415.00 ± 24.68, 491.67 ± 15.90, and 617.67 ± 3.93 mL/L, respectively. The optimization process showed that the H_max (1571.66 ± 33.71 mL/L) with a production rate of 58.02 mL/L/h and lag phase of 19.33 h was achieved by the synergistic coculture grown on 3% molasses at 40 °C, pH 7, and an inoculum size of 25% (v/v). This study revealed the economic feasibility of the synergistic effects of coculture on waste management and biohydrogen production technology.

The Cretaceous–Paleogene (K–Pg) boundary interval at Gabal Aras, Qena region (part of the southern Tethyan margin) was investigated in detail for calcareous nannofossil and foraminiferal (planktonic and benthonic) assemblages to characterize the surface and bottom sea water conditions. The K–Pg boundary is marked by a minor hiatus expressed by the absence of the lowermost Danian P0 and Pα planktonic foraminiferal zones. Benthonic foraminifera assemblages indicate moderately oxygenated bottom sea waters associated with oligo-mesotrophic conditions during early late Maastrichtian, and mesotrophic conditions during the latest Maastrichtian. The benthonic foraminiferal assemblage reflects a decrease in the food supply in the bottom sea water during the early Danian, while well-oxygenated and oligotrophic conditions dominated during late Danian. The late Maastrichtian surface water witnessed a general cooling trend that was interrupted by a warming episode that could correspond to the Late Maastrichtian Warming Event (LMWE). Acme of Thoracosphaera associated with increased abundance of Neobiscutum romeinii were observed within the upper part of NP1 Zone indicating stressful surface water conditions. The increase of the epifaunal foraminiferal taxa and the occurrence of Cruciplacolithus primus throughout NP2 and NP3 zones reflect a progressive return to normal marine conditions. In the framework of sequence stratigraphy, two third-order depositional sequences covering the K–Pg boundary interval were identified, interpreted, and correlated. The obtained sea-level curve was evaluated to assess whether it was controlled by the eustatic sea-level changes, regional tectonics, or both these factors.

Water demands have increased even more in recent decades because of the high population density.
Surface and groundwater resources are insufficient to meet these demands. As a result, governments
have turned to the treatment of sewage water. Sewage water contains multiple types of contamination,
creating a major health risk. In the research region, 48 water samples were obtained, including 18 samples
of surface water and 30 samples of groundwater. The Canadian Council Water Quality Index (CCWQI)
program calculates the water quality index to evaluate the water quality for drinking and human use. The
World Health Organization (WHO) and the Egyptian Ministry of Health (EMH) determined regulatory
limits for drinking water and each value of the investigated parameter connected with them.
According to the findings, 79% of the tested water samples are safe to drink and are excellent for human
and wildlife use. Due to infiltration or recharging of groundwater with drainage water, as well as the
involvement of dissolution, leaching processes, and anthropogenic activities that damage human health,
animals, and some plants, these samples are unfit for drinking and domestic consumption. The heavy
metal level of Cd and Pb in the examined water samples was found to be above WHO and EMH acceptable
limits. Furthermore, due to oral exposures, the examined water samples may cause complex health concerns
such as non-carcinogenic and carcinogenic influences for children over adults due to a reduction in
children’s immunity. As a result, water treatment should be carried out in the examined region to protect
the health of the residents.

Forty-eight water samples (30 groundwater and 18 surface water samples) were collected
from the study region. Physical and chemical examinations were performed on the water samples to
determine the values of various variables. Several graphs, sheets, and statistical measures, including
the sodium solubility percentage (SSP), the sodium absorption ratio (SAR), and Piper’s diagram,
were used to plot the concentration of the principal ions and the chloride mass balance (CMP). The
contents of the variables were compared with the contents in other local areas and the standard
allowable safe limits as recommended by the World Health Organization (WHO). Water pH values
were neutral for all water samples. Electric conductivity (EC) readings revealed that water samples
vacillated from slightly mineralized to excessively mineralized. Water salinities were fresh and very
fresh according to the total dissolved solids (TDS) amounts. The hardness of water ranged from
medium to hard in the surface water and from medium to very hard in the groundwater samples.
Bicarbonate, sodium, and calcium made up the highest amounts in the surface water samples. The
highest concentrations of bicarbonate, sulfate, chloride, and sodium were found in the groundwater.
Diagrams show the major ion relationships as well as the type and origin of the water. According to
Piper’s plots, most of the water samples under investigation were Ca-HCO3 type, Mg water types,
followed by SO4.Ca-Cl water types. This highlighted the elemental preponderance of bicarbonate
and alkaline earth (Ca2+ + Mg2+). This dominance is caused by evaporite and carbonate minerals
dissolving in water because of anthropogenic activities and interaction processes. The groundwater
recharge was estimated to be 0.89–1.6 mm/yr based on Chloride Mass Balance. The examined water
samples can also be used for cattle, poultry, and irrigation. Additionally, the groundwater is of poorer
quality than the surface water, although both types of water are adequate for various industries,
with a range of 14 to 94 percent. With the exception of a few groundwater samples, the tested water
samples are suitable for a number of applications.

In order to cope with the rise in human-caused demands, Saudi Arabia is exploring
new groundwater sources. The groundwater potential ofWadi Ranyah was studied using a multidataset-
integrated approach that included time-variable gravity data from the Gravity Recovery and
Climate Experiment (GRACE), vertical electrical sounding (VES), and time-domain-electromagnetic
(TDEM) data with other related datasets to examine the variations and occurrence of groundwater
storage and to define the controlling factors affecting the groundwater potential in Wadi Ranyah
in southwestern Saudi Arabia. Between April 2002 and December 2021, the estimated variation in
groundwater resources was ?3.85  0.15 mm/yr. From 2002 to 2019, the area observed an average
yearly precipitation rate of 100 mm. The sedimentary succession and the underlying fractured
basement rocks are influenced by the structural patterns that run mainly in three different trends
(NW, NE, and NS). The sedimentary cover varies from 0 to 27 m in thickness. The outputs of the
electrical sounding revealed four primary geoelectric units in the study area: on top, a highly resistant
geoelectrical unit with a resistivity of 235–1020 W.m, composed of unsorted, loose, recent sediments;
this is followed by a layer of gravel and coarse-grained sands with a resistivity of 225–980 W.m; then,
a water-bearing unit of saturated sediments and weathered, fractured, basement crystalline rocks
with a resistivity of 40–105 W.m, its depth varying from 4 to ~9 m; and then the lowest fourth unit
composed of massive basement rocks with higher resistivity values varying from 4780 to 7850 W.m.
The seven built dams store surface-water runoff in the southwestern part of the wadi, close to the
upstream section, in addition to the Ranyah dam, as the eighth one is located in the middle of
the wadi. The subsurface NW- and NS-trending fault lines impede the groundwater from flowing
downstream of the wadi, forming isolated water-bearing grabens. Minimal surface runoff might
occur in the northern part of the wadi. The combined findings are beneficial because they provide a
complete picture of the groundwater potential ofWadi Ranyah and the controlling structural patterns.
Using this integrated technique, the groundwater potential in arid and semiarid regions can now be
accurately assessed.

Human activity has led to a rise in the demand for water, prompting Saudi Arabia to search
for alternative groundwater supplies. Wadi As-Sirhan is one area that has experienced extensive
agricultural growth and the severe over-exploitation of its groundwater resources. The groundwater
drawn from the wadi should be continuously monitored to determine the best management options
for groundwater resources and economic growth. The most recent Gravity Recovery and Climate
Experiment (GRACE) mission and outputs of land surface models were combined to estimate the
depletion rate of the groundwater of the Wadi As-Sirhan drainage basin in the northern region of
Saudi Arabia throughout the period of April 2002–December 2021. The findings are: (1) the average
GRACE-derived terrestrial water storage variation (DTWS) was calculated at ?13.82  0.24 mm/yr;
(2) the soil moisture storage variation was averaged at +0.008  0.004 mm/yr; (3) the GRACE-derived
groundwater depletion rate was estimated at ?13.81  0.24 mm/yr; (4) the annual precipitation data
over the Wadi As-Sirhan was averaged at 60 mm/yr; (5) The wadi has a minimal recharge rate of
+2.31  0.24 mm/yr, which may partially compensate for a portion of the groundwater withdrawal;
(6) the sediment thickness shows an increase from 0 m at the southern igneous and volcanic rocks
to more than 3000 m close to the Saudi–Jordanian border; (7) The wadi’s eastern, southern, and
western portions are the sources of its tributaries, which ultimately drain into its northwestern
portion; (8) change detection from the Landsat photos reveals considerable agricultural expansions
over recent decades. The integrated method is useful for analyzing changes to groundwater resources
in large groundwater reservoirs and developing environmentally appropriate management programs
for these resources