In this transdisciplinary study, we investigated, using genomic tools and physico-chemical parameters, the effect of Moringa oleifera seed (MOS) on the removal of microorganisms and pharmaceutic residues (antibiotics), and also the development of antibiotic-resistant genes (ARGs) in water samples from a domestic wastewater treatment plant (WWTP) prototype. Water samples were analyzed with and without the addition of powder of MOS. The results showed that MOS addition reduced the total bacterial load from 1.73 × 10¹⁰ ± 3.21 × 10⁹ to 6.67 × 10⁶ ± 5.77 × 10⁶ CFU/L, while fecal coliforms and Escherichia coli were removed with efficiencies of 99% and 57%, respectively. Furthermore, MOS treatment resulted in a reduction in fecal coliforms and E. coli resistant to ampicillin by about 100% and 96%, respectively. The results indicated that ciprofloxacin removal efficiencies at 29 °C were over 93% (fecal coliforms) and 68% (E. coli) with doxycycline. Adding MOS significantly reduced the copy number of the 16S rRNA gene and the genes conferring resistance to β-lactam (bla_CTX-M, bla_SHV, and bla_TEM). However, MOS does not reveal real effectiveness on removal of pollutants (phosphorus and nitrates) contrary to what was expected. Additional studies are needed for confirmation from our observations. The findings of this study, whatever the functioning conditions (not optimal) of the prototype followed over 4 years, confirmed that MOS is potentially an effective natural and environmentally friendly coagulant that could be applied to wastewater treatment in low-income countries to remove or minimize multiple pollutants and control ARG spread. To promote sustainable development, this small-scale study provides guidance for designing infrastructure in resource-limited locations to take advantage of MOS effects in wastewater treatments. Graphical Abstract An individual WWTP prototype was installed in Senegal in 2018 and evaluated in 2020 and 2022. MOS powder addition is supposed to reduce bacterial loads and pharmaceutical residues in wastewater from the WWTP. Evaluation of treatment efficiency was carried out based on using chemistry, microbiology, genomics, physic-chemistry, and statistics analysis.

Developing countries are confronted with general issues of municipal wastewater management and treatment. Untreated wastewater and faecal sludge from septic tanks and traditional toilets are often discharged into rivers and used for urban agriculture without any treatment to minimize potential biorisks. Such practices result in potential environmental and public health risks. In this study, a wastewater treatment plant prototype coupled with Moringa oleifera seeds treatment was developed to evaluate their effectiveness for the reduction of faecal indicator bacteria and antibiotic-resistant bacteria in domestic wastewater. We demonstrated that that the proposed wastewater treatment plant prototype reduces bacteria by 99.34%. A high removal of the bacteria load was obtained after the addition of Moringa oleifera seeds into waters, with removal rates of 36.6–78.8% for E. coli, 28.3–84.6% for faecal coliform, 35.3–95.6% for Vibrio cholera and 32.1–92.4% for total flora. A similar effect of Moringa oleifera seeds was noted for the removal of antibiotic-resistant bacteria, extended-spectrum beta-lactamases and carbapenem-resistant Enterobacteriaceae, with a removal rate of up to 98% for E. coli and faecal coliform, 100% for Vibrio cholera and 91.96% for total flora. This study demonstrated the high removal efficiency pathogens and antibiotic-resistant bacteria from domestic wastewater using Moringa oleifera seeds.

A wastewater treatment plant (WWTP) prototype coupled with Moringa oleifera seeds (MOSs) was developed to evaluate its effectiveness to reduce metallic trace elements (MTEs) in domestic wastewater. The WWTP is composed of a septic tank (F0) where wastewater is treated by biological processes under anaerobic conditions, followed by a bacterial filter (F1) where wastewater is filtered under aerobic conditions, followed by an infiltration well (F2), which provides additional filtration of wastewater before discharge into the soil. MTEs present in waters can bind with humic substances contained in colloid particles and then be eliminated by coagulation–flocculation with a cationic polyelectrolyte. MOSs contain positively charged cationic polymers that can neutralize the colloids contained in waters, which are negatively charged. Based on this observation, 300 mg·L⁻¹ of MOS was added into F0, 50 mg·L⁻¹ into F1, and 50 mg·L⁻¹ into F2 mg·L⁻¹. MOS activation in samples was performed by stirring rapidly for 1.5 min, followed by 5 min of gentle stirring and 3 h of settling. The data analysis shows that wastewater samples had significant concentrations of MTEs, particularly for Cu, Ni, Sr, and Ti, and sediment samples had high amounts of Cr, Cu, Ni, Sr, Ti, and V. The addition of MOS to F0, F1, and F2 samples resulted in reductions in MTE concentration of up to 36%, 71%, 71%, 29%, 93%, 81%, 13%, 52%, and 67% for Co, Cr, Cu, Ni, Pb, Se, Sr, Ti, and V, respectively. The quantified MTEs (As, Co, Cr, Cu, Ni, Pb, Se and V) in treated samples were reported to be lower than UN-EP standards for a safe reuse for irrigation and MOS proved to be as effective as chemical coagulants such as lime and ferric iron for the removal of MTEs contained in wastewater. These results highlight the potential of MOSs as natural coagulants for reducing MTE content in domestic wastewater. This study could be the first to evaluate the effectiveness of MOS in reducing 10 MTEs, including As, Co, Se, Sr, Ti, and V, which are currently understudied. It could also provide a better understanding of the origin of MTEs found in domestic wastewaters and how an effective treatment process can result in high-quality treated wastewaters that can be reused for irrigation without posing health or environmental risks. However, more research on MOSs is needed to determine the type and composition of the coagulant substance found in the seeds, as well as the many mechanisms involved in the decrease in MTEs by MOSs, which is currently understudied. A better understanding of MOS structure is required to determine the optimum alternative for ensuring the optimal effect of MOS paired with WWTP in removing MTEs from domestic wastewaters.

Developing countries are confronted with general issues of municipal wastewater management and treatment. Untreated faecal sludges and wastewaters from septic tanks and traditional toilet are rejected into rivers and sometimes using for urban agriculture without any treatment to reduce the biorisk. Consequently, there are potential environmental and public health risks. In this study, a wastewater treatment plant prototype coupled with Moringa Oleifera seeds treatment was developed to evaluate their effectiveness for the reduction of faecal indicator bacteria and antibiotics resistant bacteria in domestic wastewater. Results indicate that our performed prototype system presents high capacity to reduce bacteria with abatements up to 99.34%. High reductions of bacteria load were obtained after add of Moringa Oleifera seeds into waters, with reductions varied from 36.6-78.8% for E. coli, 28.3-84.6% for Faecal coliform, 35.3-95.6% for Vibrio cholerae and 32.1-92.4% for total flora. Same effects of Moringa Oleifera seeds were noted for reducing antibiotic resistant bacteria, Extended Spectrum Beta-lactamases and Carbapenem-Resistant Enterobacteriaceae with abatements up to 98% for E. coli and faecal coliform, 100% for Vibrio cholerae and 91.96% for total flora. Our results supported high capacity of Moringa Oleifera seeds as an excellent alternative for pathogens and antibiotics resistant bacteria reduction/purification from domestic wastewater