Mahwish Ali

This study aims to investigate the removal of antibiotics and antibiotic resistance genes (ARGs) in raw domestic wastewater by various mesocosm-scale constructed wetlands (CWs) with different filter media types. These included CW1 with gravel media, CW2 with biochar media and CW3 with zeolite media. The plant of choice in the wetland was Typha latifolia and the reactor was run for 12 cycles with each cycle running for 7 days after which new influent sample was fed. Antibiotic residues (ciprofloxacin and cefixime) concentration was analyzed by HPLC method. The removal of antibiotic resistant genes including qnrs, sul1, dfr1, blaTEM, blaCTXM, blaOXA and 16 S rDNA (indicator of total bacterial biomass) were analyzed by qPCR method at varying hydraulic retention time of 3 and 7 days. The conventional pollutants (nutrients and organic) were removed with a similar removal efficiency from the three CWs. The removal efficiencies of the biochar- and zeolite-layered wetlands had higher removal efficiencies for both antibiotics compared to wetland with gravel media. The CT means reflected the increased removal efficiency of genes by the CWs in the order of blaOXA > blaCTXM > sul1 > blaTEM > qnrS > dfr1 > 16 S rDNA. The reduction in concentrations of qnrS and blaCTXM genes differed significantly across the reactors depending upon filter media types while reduction in concentrations of qnrs and sul1 was significantly different under varying HRTs. Correlation analysis suggested the removal efficiency of ARGs to be significantly associated with total antibiotic concentration (p = 0.012) and total bacterial biomass (p < 0.001). The CW with zeolite as filter media and HRT of 7 days was opted as the best choice for contaminant removal. The findings from this study suggest that constructed wetlands are a promising treatment technology for removing emerging contaminants such as antibiotics and ARGs in domestic wastewater.

Viral infections are one of the leading causes of disease worldwide. The continuous emergence of new viruses has limited the effectiveness and availability of antiviral drugs. Fungal endophytes are considered important sources for the discovery of novel antiviral agents. In this study, a bacteriophage was used as a safe and economical viral model to screen for antiviral compounds from endophytic fungi. Bacteriophage AU-1 and its host bacteria (Escherichia coli) were isolated from sewage water. The endophytic fungus Cepalotheca foveolata (N11) was screened using a plaque reduction assay. The fungal extract was fractionated via liquid-liquid partition, and its antiphage activity was evaluated against the isolated lytic bacteriophage using a plaque reduction assay. Cytotoxicity was assessed using the Artemia salina model, and chemical profiling of active fractions was performed using Gas Chromatography-Mass Spectrometry (GC-MS). C. foveolata crude extracts exhibited strong anti-phage activity, showing 100% plaque reduction at 1 mg/100 µL. Following pilot-scale cultivation, the extract was purified by silica-gel column chromatography. Active pooled fractions (F31–F40) showed > 93% plaque inhibition at 0.4 mg/100 µL. GC-MS analysis revealed four major compounds, including benzophenone, a known antiviral agent. The results demonstrate the utility of bacteriophage-based assays for the preliminary screening of antiviral compounds from fungal extracts. This approach is simple, safe, and cost-effective, and the identified extracts warrant further investigation for the isolation of potential antiviral agents. Graphical Abstract

Antibiotic-resistant bacteria (ARB) pose a significant and growing threat to public health, particularly in wastewater environments where they can persist and propagate, exacerbating the global antibiotic resistance crisis. Conventional wastewater treatment methods often fall short in effectively removing ARB and associated contaminants, creating an urgent need for innovative and sustainable solutions. This research addresses this critical gap by investigating the use of a lab-scale horizontal subsurface flow constructed wetland (CW) planted with Typha latifolia and Phragmites australis to enhance domestic wastewater treatment. Biochar was selected as the substrate medium due to its high adsorption capacity and ability to support microbial communities that contribute to contaminant degradation. The CW system was operated at a flow rate of 3.8 US gallons/day and a moderate organic loading rate, with influent concentrations of 698 mg/L for chemical oxygen demand (COD), 376 mg/L for biological oxygen demand (BOD), 43 mg/L for nitrogen and 51 mg/L for sulfate. The results showed that the removal efficiencies of various physiochemical parameters were 53%, 57%, 81%, 80%, and 81% for total dissolved solids (TDS), COD, BOD, total nitrogen and total sulphate, respectively. Importantly, antibiotic-resistant bacteria were reduced by 99%, highlighting the system’s capability to mitigate the spread of multidrug-resistant (MDR) strains. Screening for antibiotic-resistant β-lactamase genes revealed that blaTEM was detected in 50% of MDR isolates from influent samples, while blaCTX-M was absent in both influent and effluent. These findings emphasize the potential of constructed wetlands with biochar as a sustainable and cost-effective solution for addressing the dual challenges of environmental pollution and antibiotic resistance. This study provides critical insights into the development of advanced wastewater treatment technologies to combat emerging public health threats.

Sugarcane accounts for around 80% of global sugar production. However, the sugar industry is known for producing significant amounts of organic wastewater with a high COD (5000–8000 mg/L) that severely pollutes the environment. A lab-scale trial was conducted to evaluate the efficacy of a horizontal subsurface flow wetland planted with Typha latifolia and Phragmites australis in removing pollutants from sugar industry wastewater. The wetland system was subjected to rigorous testing, operating at a high flow rate of 2.166 gallons per day and exposed to a high organic loading rate (3800 mg/L COD and 2470 mg/L BOD), as well as elevated levels of inorganic nitrogen, sulfate, and phosphate (100 mg/L, 80 mg/L, and 10 mg/L, respectively). Our findings indicate significant removal efficiencies, with the wetland system achieving removal rates of 88% for COD, 97% for BOD, 96% for total nitrogen, and 95% for sulfate. Remarkably, the system exhibited enhanced removal efficiency when exposed to domestic wastewater compared to tap water, owing to the abundance of microbial populations. Moreover, toxicity assessments conducted on the treated water revealed no adverse effects on the germination of wheat seeds and on the survival of fish over a week-long observation period. In conclusion, our study underscores the promising potential of horizontal subsurface flow wetlands as an effective and sustainable approach for mitigating the adverse environmental impacts associated with sugar industry wastewater. The findings offer valuable insights for policymakers and stakeholders in devising strategies to promote environmental sustainability and safeguard vital ecosystems in the Sindh region of Pakistan and beyond.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a human coronaviruses that emerged in China at Wuhan city, Hubei province during December 2019. Subsequently, SARS-CoV-2 has spread worldwide and caused millions of deaths around the globe. Several compounds and vaccines have been proposed to tackle this crisis. Novel recommended in silico approaches have been commonly used to screen for specific SARS-CoV-2 inhibitors of different types. Herein, the phytochemicals of Pakistani medicinal plants (especially Artemisia annua) were virtually screened to identify potential inhibitors of the SARS-CoV-2 main protease enzyme. The X-ray crystal structure of the main protease of SARS-CoV-2 with an N3 inhibitor was obtained from the protein data bank while A. annua phytochemicals were retrieved from different drug databases. The docking technique was carried out to assess the binding efficacy of the retrieved phytochemicals; the docking results revealed that several phytochemicals have potential to inhibit the SARS-CoV-2 main protease enzyme. Among the total docked compounds, the top-10 docked complexes were considered for further study and evaluated for their physiochemical and pharmacokinetic properties. The top-3 docked complexes with the best binding energies were as follows: the top-1 docked complex with a −7 kcal/mol binding energy score, the top-2 docked complex with a −6.9 kcal/mol binding energy score, and the top-3 docked complex with a −6.8 kcal/mol binding energy score. These complexes were subjected to a molecular dynamic simulation analysis for further validation to check the dynamic behavior of the selected top-complexes. During the whole simulation time, no major changes were observed in the docked complexes, which indicated complex stability. Additionally, the free binding energies for the selected docked complexes were also estimated via the MM-GB/PBSA approach, and the results revealed that the total delta energies of MMGBSA were −24.23 kcal/mol, −26.38 kcal/mol, and −25 kcal/mol for top-1, top-2, and top-3, respectively. MMPBSA calculated the delta total energy as −17.23 kcal/mol (top-1 complex), −24.75 kcal/mol (top-2 complex), and −24.86 kcal/mol (top-3 complex). This study explored in silico screened phytochemicals against the main protease of the SARS-CoV-2 virus; however, the findings require an experimentally based study to further validate the obtained results.

The present study explored the efficiency of a four-chambered anaerobic baffled reactor (ABR) as a cost-effective and sustainable method of organic pollutant and pathogen removal from domestic wastewater, under a range of environmental conditions. An ABR with a circular additional filter at the outlet pipe was constructed to treat wastewater from a residential colony of 108 households with an average inflow of 110 m³/day and a nominal hydraulic retention time (HRT) of 20 h. Analysis of the chemical oxygen demand (COD), total nitrogen, sulfate and phosphate load, and total coliform removal for 2 years of operation, 2015 and 2017, showed a COD of 46%, sulfate load of 28%, phosphate load of 51% and total nitrogen of 28% for 2015, compared to a COD of 48%, sulfate load of 44%, phosphate load of 58% and total nitrogen of 31% for 2017. The lack of a significant effect of sludge removal suggested a stable process. The overall efficiency of the ABR increased in the summer, including for pathogen removal, which was significantly higher during the summer months of both years. Overall, the ABR was found to be able to consistently treat primary wastewater, although tertiary effluent treatment was still required before water reuse or final discharge.