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This study examines substances from plant leaves of Azadirachta indicaand Melia azedarachextracted with methanol (80%) and then successively fractionated with increasing gradient polarity solvents. The methanol extract from the two plant leaves was selected to be incorporated with nanocomposites because of their high antimicrobial activities. HPLC analysis was performed for the determination of total phenolics and flavonoids. LC–ESI–MS positive ion acquisition mode revealed the presence of four main chemical classes: limonoids, triterpenes, fatty acids, and phenolics. Sol–gel processes were adapted to prepare CaO/chitosan composite loaded with the methanol extract of the two plant leaves, acting as innovative antibacterial agents. The fabricated nanocomposites were characterized by XRD, TEM, SEM, and FTIR methods. Minimal bactericidal concentrations (MBC) were established by agar plating using bacteria treated with MIC and at least 2 concentrations double higher than the MIC. Biofilm was cultivated in the presence of sub-MICs of the extracts and the nanocomposites, followed by quantification with the crystal violet assay. The examined chitosan–CaO-based hybrid nanocomposites loaded with the methanol fractions from the leaves of A. indicaand M. azedarachhad an excellent performance as biofilm inhibitors. This indicates their good potential for biomedical applications.

The current study summarizes the current status of wastewater stabilization ponds (WSPs) treatment plants that have already been built in 11 governorates throughout Egypt. Moreover, this study aims to determine the most appropriate chlorine dose for waste stabilization ponds (WSPs) effluents to ensure the treated effluents are suitable for reuse in unrestricted irrigation and to comply with the current legislation on direct discharge onto water bodies. According to the findings, the chlorine doses used as a disinfectant in the treated effluents of the majority of WSP treatment plants ranged from 3 to 13 mg/L. Meanwhile, two of the WSPs treatment plants effluents, the Qus WSPs treatment plant in Qena governorate and the Al Zarabii WSPs treatment plant in Asyut governorate used high chlorine doses reached to 17 and 19 mg/L, respectively. This is due to the fact that both the Qus and Al Zarabii WSPs treatment plants have a high organic load, which necessitated the use of more chlorine to achieve the optimum chlorine dose at 13 mg/L for Qus and 11mg/L for Al Zarabii. The findings demonstrated that chlorine has a powerful effect in completely removing bacteria. Furthermore, in most chlorine-treated wastewater final effluents, as the chlorine doses increased, the chlorophyll-a reading decreased. The amount of trihalomethanes (THMs) produced as disinfectant byproduct was measured. The results proved that the water can be used in unrestricted irrigation, and after adding chlorine, it can be dumped on water bodies without health risks.