The focus of this review article was to outline the sources, pathways, effects, occurrence, and spatial distribution of the most prescribed pharmaceuticals in wastewater and receiving waters of South Africa. Google Scholar, Web of Science, and Scopus were used to gather data from different regions. A zone-wise classification method was used to determine the spatial distribution and data deficiencies in different regions of South Africa. This review revealed that over 100 pharmaceutical compounds have been reported in South Africa’s various water sources and wastewater, with most studies and highest concentrations being documented in Gauteng and Kwa-Zulu Natal. The pharmaceutical concentration in water samples ranged from ng/L to µg/L. Aspirin, ketoprofen, diclofenac, ibuprofen, naproxen, erythromycin, tetracycline, sulfamethoxazole, acetaminophen, streptomycin, ciprofloxacin, ampicillin, carbamazepine, atenolol, pindolol, efavirenz, and zidovudine residues were among the frequently detected pharmaceutical residues in water bodies and wastewaters of South Africa. Based on the spatial distribution data, Gauteng has the highest number of pharmaceuticals (108) detected in waste and surface water, with the Northern Cape having no monitoring evidence. Therefore, to precisely ascertain the geographical distribution of pharmaceutical contaminants in South Africa, this review recommends that further research be carried out to track their occurrence in aquatic environments and WWTP, especially in isolated regions like Limpopo.

This study focuses on time-dependent microwave-assisted biosynthesis of silver nanoparticles using aqueous peel extracts of Citrus paradisi as a reducing, stabilizing and capping agent with emphasis on its antibacterial property. Optical, structural and morphological properties of the synthesized Citrus paradisi peel extract silver nanoparticle (CPAgNp) were characterized using UV-visible spectrophotometer, transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Brunauer–Emmett–Teller (BET) and X-ray diffractometer (XRD). The antimicrobial activity was evaluated using the well- and disc-diffusion methods. Characteristic surface plasmon resonance (SPR) wavelength in the range of 420–440 nm at an optimized intensity growth rate typical of silver nanoparticles was obtained. The synthesized CPAgNp are spherical in shape having the size range of 14.84 ± 5 nm and possessing fcc unit phase structure. The Citrus paradisi peel extract mediated AgNp were found to possess a broad-spectrum antimicrobial activity against water-borne pathogenic microbes. GRAPHICAL ABSTRACT

Some antibiotics have lost their efficacy over common infections and this has led to the search for new antibiotics and chemically altering existing ones for a better control of infectious diseases. In the present study, Pyrenacantha grandiflora tubers extracts were conjugated with ampicillin, penicillin, vancomycin and silver nanoparticles and their antimicrobial activity was evaluated against Escherichia coli, Staphylococcus aureus and Klebsiella Pneumoniae. The reactions were confirmed by formation of new functional groups that were identified by Fourier transmission infrared spectroscopy (FTIR). Minimum inhibitory concentrations were determined using the microdilution assay. Minimum bactericidal concentrations and the fractional inhibition concentration index were also determined. FTIR analysis indicated different functional group associated with conjugation. The activity of ampicillin was improved when conjugated with silver nanoparticles against K. pneumonia and E. coli. Vancomycin showed improvement of activity when conjugated to silver nanoparticles against K. pneumonia. Penicillin was improved by acetone extracts and vancomycin showed to be more effective when conjugated with silver nanoparticles and water extracts. The conjugation of P. grandiflora with penicillin, ampicillin and vancomycin in the presence of silver nanoparticles improved their biological activities. Therefore, the conjugates are medicinally important and can be used to improve the activity of existing antibiotics.

This study reports a green synthesis route for a bilayered Ag-MgO nanocomposite using aqueous peel extract of Citrus paradisi (grapefruit red) under an accelerated uniform heating technique and its antibacterial potency against Escherichia coli. Surface modifications and composition of the nanocomposite were examined using a UV-visible spectrophotometer, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) equipped with an energy dispersive X-ray (EDX) analyzer. The efficiencies of the as-synthesized Ag-MgO nanocomposite against Escherichia coli were examined. The synthesized Ag-MgO nanocomposite showed characteristic synergetic bands at 290 nm for MgO nanoparticle and at around 440 nm for Ag nanoparticle which blue-shifted to 380 nm in the composite. A spherically dispersed nanocomposite with cubical crystal lattice network with a diameter of about 20–100 nm comprising Ag nanoparticle embedded within MgO nanoparticles was obtained. The nanocomposite produced stronger antibacterial activity against Escherichia coli as compared to MgO nanoparticle, indicating a higher interaction between Ag and MgO ions. The nanocomposite was successfully synthesized via an efficient modified method by bioreductive agents with an improved synergistic antibacterial property towards water purification.

The global dairy sector produces upwards of 900 million tonnes of milk each year, resulting in 2.25 billion tonnes of wastewater being generated. This is significant in the South African context as a large percentage of the population lives without reliable access to clean, reliable water. The treatment of dairy wastewater (DWW) in this context would help alleviate the unavailability for many people in this country. DWW has a high fat content along with a high chemical oxygen demand (COD), which makes it problematic to dispose of. Biological treatment processes have shown great success in the remediation of this water. However, these are not without their shortfalls. A variety of biological processes have been listed here as well as suggestions to improve their effectiveness. To improve the treatment efficiency, there are two main lines of thinking: First, to optimise the process through the manipulation of the physical parameters of the systems (e.g., temperature, pH, hydraulic retention time (HRT), agitation, etc.). Second, to add either pre-treatment or post-treatment processes to the main process to increase the effectiveness of the entire process overall. These different options have been discussed, with suggestions being made on the way forward.