Effects of untreated hospital effluents on the accumulation of toxic metals in sediments of receiving system under tropical conditions: case of South India and Democratic Republic of Congo

Meta-analysis addressing the characterization of antibiotic resistome in global hospital wastewater

Hospital wastewater (HWW) is a significant environmental reservoir of antibiotic resistance genes (ARGs). However, currently, no comprehensive understanding exists of the antibiotic resistome in global HWW. In this study, we attempted to address this knowledge gap through an in silico reanalysis of publicly accessible global HWW metagenomic data. We reanalyzed ARGs in 338 HWW samples from 13 countries in Africa, Asia, and Europe. In total, 2420 ARG subtypes belonging to 30 ARG types were detected, dominated by multidrug, beta-lactam, and aminoglycoside resistance genes. ARG composition in Europe differed from that in Asia and Africa. Notably, the ARGs presented co-occurrence with mobile genetic elements (MGEs), metal resistance genes (MRGs), and human bacterial pathogens (HBP), indicating a potential dissemination risk of ARGs in the HWW. Multidrug resistance genes presented co-occurrence with MGEs, MRGs, and HBP, is particularly pronounced. The abundance of contigs that contained ARG, contigs that contained ARG and HBP, contigs that contained ARG and MGE, contigs that contained ARG and MRG were used for health and transmission risk assessment of antibiotic resistome and screened out 40 high risk ARGs in the global HWW. This study first provides a comprehensive characterization and risk of the antibiotic resistome in global HWW.

Wastewater from healthcare centers in Burkina Faso is a source of ESBL, AmpC-β-lactamase and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae

BACKGROUND

Extended-spectrum β-lactamase (ESBL), plasmid-mediated AmpC-β-lactamase and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae have spread into the environment worldwide posing a potential public health threat. However, the prevalence data for low- and middle-income countries are still scarce. The aim of this study was to evaluate the presence of ESBL, AmpC-β-lactamase and carbapenemase-producing and multidrug-resistant E. coli and K. pneumoniae in wastewaters from healthcare centers in Burkina Faso.

RESULTS

Eighty-four (84) wastewater samples were collected from five healthcare centers and plated on selective ESBL ChromAgar. E. coli and Klebsiella pneumoniae isolates were identified using API20E. ESBL-producing bacteria were detected in 97.6% of the samples and their average concentration per hospital ranged from 1.10 × 105 to 5.23 × 106 CFU/mL. Out of 170 putative ESBL-producing isolates (64% of them were E. coli) and 51 putative AmpC-β-lactamase-producing isolates, 95% and 45% were confirmed, respectively. Carbapenemase production was detected in 10 isolates, of which 6 were NDM producers, 3 were OXA-48 producers and 1 was NDM and OXA-48 producer. All isolates were multidrug resistant and, moreover, all of them were resistant to all tested β-lactams. Resistance to ESBL inhibitors was also common, up to 66% in E. coli and 62% in K. pneumoniae. Amikacin, fosfomycin and nitrofurantoin were the antibiotics to which the least resistance was detected.

CONCLUSIONS

This study showed that wastewater from healthcare centers constitutes a reservoir of multidrug-resistant bacteria in Burkina Faso, including carbapenemase producers. Untreated healthcare wastewater entering the environment exposes people and animals to infections caused by these multi-resistant bacteria, which are difficult to treat, especially in the resource-poor settings.

A critical assessment of SARS-CoV-2 in aqueous environment: Existence, detection, survival, wastewater-based surveillance, inactivation methods, and effective management of COVID-19

In early January 2020, the causal agent of unspecified pneumonia cases detected in China and elsewhere was identified as a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and was the major cause of the COVID-19 outbreak. Later, the World Health Organization (WHO) proclaimed the COVID-19 pandemic a worldwide public health emergency on January 30, 2020. Since then, many studies have been published on this topic. In the present study, bibliometric analysis has been performed to analyze the research hotspots of the coronavirus. Coronavirus transmission, detection methods, potential risks of infection, and effective management practices have been discussed in the present review. Identification and quantification of SARS-CoV-2 viral loads in various water matrices have been reviewed. It was observed that the viral shedding through urine and feces of COVID-19-infected patients might be a primary mode of SARS-CoV-2 transmission in water and wastewater. In this context, the present review highlights wastewater-based epidemiology (WBE)/sewage surveillance, which can be utilized as an effective tool for tracking the transmission of COVID-19. This review also emphasizes the role of different disinfection techniques, such as chlorination, ultraviolet irradiation, and ozonation, for the inactivation of coronavirus. In addition, the application of computational modeling methods has been discussed for the effective management of COVID-19.

Combined Chemical and Ecotoxicological Measurements for River Sediment Management in an On-Land Deposit Scenario

Sediment management along engineered river systems includes dredging operations and sediment deposition in the sea (capping) or on land. Thus, determining the ecotoxicological risk gradient associated with river sediments is critical. In this study, we investigated sediment samples along the Rhône River (France) and conducted environmental risk assessment tests with the idea to evaluate them in the future for deposit on soil. Based on an on-land deposit scenario, the capacity of the sediment samples from four sites (LDB, BER, GEC, and TRS) to support vegetation was evaluated by characterising the physical and chemical parameters (pH, conductivity, total organic carbon, grain size, C/N, potassium, nitrogen, and selected pollutants), including polychlorinated biphenyls (PCBs) and metal trace elements. All tested sediments were contaminated by metallic elements and PCBs as follows: LDB > GEC > TRS > BER, but only LDB had levels higher than the French regulatory threshold S1. Sediment ecotoxicity was then assessed using acute (plant germination and earthworm avoidance) and chronic (ostracod test and earthworm reproduction) bioassays. Two of the tested plant species, Lolium perenne (ray grass) and Cucurbita pepo (zucchini), were highly sensitive to sediment phytotoxicity. Acute tests also showed significant inhibition of germination and root growth, with avoidance by Eisenia fetida at the least contaminated sites (TRS and BER). Chronic bioassays revealed that LDB and TRS sediment were significantly toxic to E. fetida and Heterocypris incongruens (Ostracoda), and GEC sediment was toxic for the latter organism. In this on-land and spatialised deposit scenario, river sediment from the LDB site (Lake Bourget marina) presented the highest potential toxicity and required the greatest attention. However, low contamination levels can also lead to potential toxicity (as demonstrated for GEC and TRS site), underlining the importance of a multiple test approach for this scenario.

Global trends in the research and development of medical/pharmaceutical wastewater treatment over the half-century

The COVID-19 pandemic has severely impacted public health and the worldwide economy. The overstretched operation of health systems around the world is accompanied by potential and ongoing environmental threats. At present, comprehensive scientific assessments of research on temporal changes in medical/pharmaceutical wastewater (MPWW), as well as estimations of researcher networks and scientific productivity are lacking. Therefore, we conducted a thorough literature study, using bibliometrics to reproduce research on medical wastewater over nearly half a century. Our primary goal is systematically to map the evolution of keyword clusters over time, and to obtain the structure and credibility of clusters. Our secondary objective was to measure research network performance (country, institution, and author) using CiteSpace and VOSviewer. We extracted 2306 papers published between 1981 and 2022. The co-cited reference network identified 16 clusters with well-structured networks (Q = 0.7716, S = 0.896). The main trends were as follows: 1) Early MPWW research prioritized sources of wastewater, and this cluster was considered to be the mainstream research frontier and direction, representing an important source and priority research area. 2) Mid-term research focused on characteristic contaminants and detection technologies. Particularly during 2000-2010, a period of rapid developments in global medical systems, pharmaceutical compounds (PhCs) in MPWW were recognized as a major threat to human health and the environment. 3) Recent research has focused on novel degradation technologies for PhC-containing MPWW, with high scores for research on biological methods. Wastewater-based epidemiology has emerged as being consistent with or predictive of the number of confirmed COVID-19 cases. Therefore, the application of MPWW in COVID-19 tracing will be of great interest to environmentalists. These results could guide the future direction of funding agencies and research groups.

Metagenomic Insight into Microbiome and Antibiotic Resistance Genes of High Clinical Concern in Urban and Rural Hospital Wastewater of Northern India Origin: a Major Reservoir of Antimicrobial Resistance

India is one of the largest consumers and producers of antibiotics and a hot spot for the emergence and proliferation of antimicrobial resistance genes (ARGs). Indian hospital wastewater (HWW) accumulates ARGs from source hospitals and often merges with urban wastewater, with the potential for environmental and human contamination. Despite its putative clinical importance, there is a lack of high-resolution resistome profiling of Indian hospital wastewater, with most studies either relying on conventional PCR-biased techniques or being limited to one city. In this study, we comprehensively analyzed antibiotic resistomes of wastewater from six Indian hospitals distributed in rural and urban areas of northern India through shotgun metagenomics. Our study revealed the predominance of ARGs against aminoglycoside, macrolide, carbapenem, trimethoprim, and sulfonamide antibiotics in all the samples through both read-based analysis and assembly-based analysis. We detected the mobile colistin resistance gene mcr-5.1 for the first time in Indian hospital sewage. blaNDM-1 was present in 4 out of 6 samples and was carried by Pseudomonas aeruginosa in HWW-2, Klebsiella pneumoniae in HWW-4 and HWW-6, and Acinetobacter baumanii in HWW-5. Most ARGs were plasmid-mediated and hosted by Proteobacteria. We identified virulence factors and transposable elements flanking the ARGs, highlighting the role of horizontal gene transmission of ARGs. IMPORTANCE There is a paucity of research on detailed antibiotic resistome and microbiome diversity of Indian hospital wastewater. This study reports the predominance of clinically concerning ARGs such as the beta-lactamases blaNDM and blaOXA and the colistin resistance gene mcr and their association with the microbiome in six different Indian hospital wastewaters of both urban and rural origin. The abundance of plasmid-mediated ARGs and virulence factors calls for urgent AMR crisis management. The lack of proper wastewater management strategies meeting international standards and open drainage systems further complicates the problem of containing the ARGs at these hospitals. This metagenomic study presents the current AMR profile propagating in hospital settings in India and can be used as a reference for future surveillance and risk management of ARGs in Indian hospitals.

Pharmaceuticals in water as emerging pollutants for river health: A critical review under Indian conditions

The wastewaters from pharmaceutical manufacturing units, hospitals, and domestic sewage contaminated with excretal matters of medicine users are the prime sources of pharmaceutical pollutants (PPs) in natural water bodies. In the present study, PPs have been considered one of the emerging pollutants (EPs) and a cause of concern in river health assessment. Beyond the reported increase in antibiotic-resistant bacteria (ABRB), PPs have been found adversely affecting the biotic diversity in such water environments. Considering Algae, Macroinvertebrates, and Fishes as three distinct trophic level indicators, the present study puts forward a framework for showing River Health Condition (RHC) based on the calculation of a River Health Index (RHI). The RHI is calculated using six Indicator Group Scores (IGS) which individually reflect river health in a defined category of water quality characteristics. While Dissolved Oxygen Related Parameters (DORP), Nutrients (NT), and PPs are taken as causative agents affecting RHCs, scores of Algal-Bacterial (AB) symbiosis, Macroinvertebrates (MI), and Fishes (F) are considered as an effect of such environmental conditions. Current wastewater treatment technologies are also not very effective in the removal of PPs. The objective of the present study is to review the harmful effects of PPs on the aquatic environment, particularly on the chemical and biotic indicators of river health. Based on predicted no-effect concentrations (PNEC) for algae, macroinvertebrates, and fishes in the aquatic environment and measured environmental concentration (MEC) in the river, the estimated risk quotient (RQ) for norfloxacin in the Isakavagu-Nakkavagu stream of river Godavari, Hyderabad is found 293 for algae, 39 for MI, and 335 for fish. Among PPs, in Indian rivers, the presence of caffeine is the most frequent, with algae at the highest level of risk (RQ_max= 24.5). Broadly six PPs, including azithromycin, caffeine, diclofenac, naproxen, norfloxacin, and sulfamethoxazole are found above PNEC values in Indian rivers. The application of IGS and RHI in understanding and presenting the river health condition (RHC) through colored hexagons has been demonstrated for the river Ganga near Varanasi (India) as an example. Identification of critical indicator groups, based on IGS provides a scientific basis for planned intervention for river health restoration to achieve an acceptable category.

Natural and anthropogenic sources of potentially toxic elements to aquatic environment: a systematic literature review

Potentially toxic elements (PTEs) constitute a class of metals, semimetals, and non-metals that are of concern due to their persistence, toxicity, bioaccumulation, and biomagnification in high concentrations, posing risks to the ecosystem and to human health. A systematic literature review (SLR) was used in this study to identify natural and anthropogenic sources of PTEs for the aquatic environment. The databases consulted were ScienceDirect, Scopus, and Web of Science, in the period 2000-2020, using specific terms and filters. After analyzing the titles, abstracts, and full texts, 79 articles were selected for the SLR, in which 15 sources and 16 PTEs were identified. The main anthropogenic sources identified were mining, agriculture, industries, and domestic effluents, and the main natural sources identified were weathering of rocks and geogenic origin. Some places where environmental remediation studies can be carried out were highlighted such as Guangdong province, in China, presenting values of Cd, Cr, and Cu exceeding the national legislation from drinking water and soil quality, and Ardabil Province, in Iran, presenting values of As, Cr, Cu, Ni, Zn, and Pb exceeding the standard for freshwater sediments of USEPA, among others places. With the results exposed in this work, the government and the competent bodies of each locality will be able to develop strategies and public policies aimed at the main sources and places of contamination, in order to prevent and remedy the pollution of aquatic environments by potentially toxic elements.

An assessment of hospital wastewater and biomedical waste generation, existing legislations, risk assessment, treatment processes, and scenario during COVID-19

Hospitals release significant quantities of wastewater (HWW) and biomedical waste (BMW), which hosts a wide range of contaminants that can adversely affect the environment if left untreated. The COVID-19 outbreak has further increased hospital waste generation over the past two years. In this context, a thorough literature study was carried out to reveal the negative implications of untreated hospital waste and delineate the proper ways to handle them. Conventional treatment methods can remove only 50%-70% of the emerging contaminants (ECs) present in the HWW. Still, many countries have not implemented suitable treatment methods to treat the HWW in-situ. This review presents an overview of worldwide HWW generation, regulations, and guidelines on HWW management and highlights the various treatment techniques for efficiently removing ECs from HWW. When combined with advanced oxidation processes, biological or physical treatment processes could remove around 90% of ECs. Analgesics were found to be more easily removed than antibiotics, β-blockers, and X-ray contrast media. The different environmental implications of BMW have also been highlighted. Mishandling of BMW can spread infections, deadly diseases, and hazardous waste into the environment. Hence, the different steps associated with collection to final disposal of BMW have been delineated to minimize the associated health risks. The paper circumscribes the multiple aspects of efficient hospital waste management and may be instrumental during the COVID-19 pandemic when the waste generation from all hospitals worldwide has increased significantly.

A review on disinfection technologies for controlling the antibiotic resistance spread

The occurrence of antibiotic-resistant bacteria (ARB) in water bodies poses a sanitary and environmental risk. These ARB and other mobile genetic elements can be easily spread from hospital facilities, the point in which, for sure, they are more concentrated. For this reason, novel clean and efficient technologies are being developed for allowing to remove these ARB and other mobile genetic elements before their uncontrolled spread. In this paper, a review on the recent knowledge about the state of the art of the main disinfection technologies to control the antibiotic resistance spread from natural water, wastewater, and hospital wastewater (including urine matrices) is reported. These technologies involve not only conventional processes, but also the recent advances on advanced oxidation processes (AOPs), including electrochemical advanced oxidation processes (EAOPs). This review summarizes the state of the art on the applicability of these technologies and also focuses on the description of the disinfection mechanisms by each technology, highlighting the promising impact of EAOPs on the remediation of this important environmental and health problem.

Identification and characterization of vancomycin-resistant Staphylococcus aureus in hospital wastewaters: evidence of horizontal spread of antimicrobial resistance

Antibiotic resistance has become a major threat to human health around the world, but its spread through the aquatic environment has been often overlooked. This study aimed to determine the occurrence of vancomycin-resistant Staphylococcus aureus in hospital wastewaters and their transmission into public water bodies in Kerala, India. A total of 113 S. aureus were isolated from three hospital effluents in Kerala, India. Standard disc diffusion and the strip method were used for antibiotic susceptibility testing and minimum inhibitory concentration detection. Plasmid-mediated vancomycin resistance was confirmed by plasmid curing and conjugation; resistant genes were detected by the polymerase chain reaction (PCR). Nearly 76% of S. aureus isolates were resistant to β-lactams, chloramphenicol, macrolides, aminoglycosides, and glycopeptide class of antibiotics. Among the vancomycin-resistant Staphylococcus aureus (VRSA) isolates, the prevalence rates of vanA and vanB resistance-encoding genes were 46.5 and 59.3%, respectively. Through the broth mating method, vanA gene was successfully transferred from VRSA donor to vancomycin-sensitive S. aureus. The study strongly indicates the contamination of water bodies with antibiotic-resistant bacteria from hospital discharges, their dissemination and possible transfer to microbes in the aquatic environment, posing a serious threat for public health.

Efficiency of Fez WWTP: multi-parameter evaluation of water and sediment quality

In order to assess the impact of the proper functioning of wastewater treatment plants (WWTPs) and sanitation networks on the quality of water and surface sediments of the Oued Fez River and its tributaries, and ultimately their outlet in the Sebou River, physico-chemical, geochemical and mineralogical analyses were performed. The components were studied in high- and low-water regimes at eight sites. Seven heavy metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were investigated in the sediments, with a decreasing trend being identified as Zn > Cu > Pb > Cr > As > Ni > Cd, and a mobility sequence as Cu > Pb > Zn > Ni > Cr. A comparison of the total heavy metal concentrations in the Oued Fez and Sebou River sediments with those of previous studies indicated a reduction in the harmful and polluting contribution of the Oued Fez to the Sebou River. The heavy metal assessment was achieved using environmental indices and sediment quality guidelines. The obtained results indicate that the presence of heavy metals in the sediment mainly comes from anthropogenic activities. Based on these results and their comparison with those from previous studies, the contribution of WWTPs and sanitation networks to improving the water quality of the middle Sebou River is clearly noteworthy.

Assessment of the quality of effluent management from university hospitals in the Littoral department in Benin

Background

Liquid discharges from hospitals (effluents) threaten the environment and are now a central concern of all stakeholders in the health system and those in the protection of the environment. The management of effluents is a major problem in developing countries. The objective of this study was to assess the quality of effluent management at the level of university hospital centers (CHU) in the Littoral region in Benin.

Methods

It was a cross-sectional, descriptive, evaluative study that took place in 2020 to assess the “structure”, “process” and “results” components according to standard thresholds (Bad: < 60%; Acceptable: [60–80% [and Good: ≥ 80%).

Results

In all the CHUs, all the components, as well as the overall quality of the management of hospital effluents, had a score between 0 and 60%, with an assessment deemed bad. The poor quality of the process highlighted the non-compliance with standards relating to the management of hospital liquid discharges. Several factors linked to the “structure”, “process” and “results” components at the same time explain this poor management of university hospitals effluents.

Conclusion

These effluents discharged without prior treatment into wastewater could constitute a source of dissemination of potentially pathogenic microorganisms. It is therefore important to develop methods for treating these effluents before they are released into the natural environment.

Impact of anthropogenic activities on the occurrence and distribution of toxic metals, extending-spectra β-lactamases and carbapenem resistance in sub-Saharan African urban rivers

The occurrence and dissemination of toxic metals, antibiotic resistant bacteria and their resistance genes (ARGs) in the aquatic ecosystems of sub-Saharan African countries are still understudied, despite their potential to threat human health and aquatic organisms. In this context, the co-contamination and seasonal distribution of toxic metals and ARG in river sediments receiving untreated urban sewages and hospital effluents from Kinshasa, the capital city of the Democratic Republic of the Congo were investigated. ARGs including β-lactam resistance (bla_CTX-M and bla_SHV), carbapenem resistance (bla_VIM, bla_IMP, bla_KPC, bla_OXA-48 and bla_NDM) and total bacterial load were quantified by using quantitative polymerase chain reaction (qPCR) in total DNA extracted from sediment. The amount of toxic metals in sediments was quantified using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results highlight high abundance of 16S rRNA and ARGs copy numbers in sediment samples. Strong pollution of rivers by toxic metals was found, with max values (mg kg^-1) of 81.85(Cr), 5.09(Co), 33.84(Ni), 203.46 (Cu), 1055.92(Zn), 324.24(Pb) and 2.96(Hg). Results also highlight the high abundance of bacterial markers (8.06 × 10⁹-2.42 × 10¹² 16S rRNA/g^-1 DS) as well as antibiotic resistance genes (up to 4.58 × 10⁸ ARG. g^-1 DS) in the studied rivers. Significant correlations were observed between (i) metals (except Cd and Hg) and organic matter (R > 0.60, p < 0.05); and (ii) ARGs (except bla_NDM) and 16S rRNA (R > 0.57, p < 0.05) suggesting a tight link between (i) metal contamination and anthropogenic pressure and (ii) microbial contamination of river and dissemination of antibiotic resistance. Results demonstrated that multi-diffuse pollution originating from human activity contribute to the spread of toxic metals and ARGs into the aquatic ecosystems.

Hospital wastewater treatment scenario around the globe

Wastewaters generated from hospitals contain pharmaceuticals residues, pathogens, chemical reagents, radionuclide, and other harmful matter. The wastewater characteristics, quantity, and handling methods have not only variations among countries but also within a country. Some hazardous substances of hospital wastewaters (HWWs) may have a regulatory status and should be treated accordingly while others have characteristics similar to that of domestic sewage. At a global level, guidelines do exist for treatment of these HWWs. But literatures have shown that legislation has various loopholes in implementation. This chapter outlines the current status of management and handling of HWWs around the major industrial hubs of worlds in two categories of developed (the United States, United Kingdom, and Europe) and developing (India, China, Iran, and Bangladesh) countries. Various literatures and guidelines of these countries have been referred which mainly highlight different treatment scenarios and status of coverage of HWW management guidelines.

Determination of metals and pharmaceutical compounds released in hospital wastewater from Toluca, Mexico, and evaluation of their toxic impact

Due to the activities inherent to medical care units, the hospital effluent released contains diverse contaminants such as tensoactives, disinfectants, metals, pharmaceutical products and chemical reagents, which are potentially toxic to the environment since they receive no treatment or are not effectively removed by such treatment before entering the drain. They are incorporated into municipal wastewater, eventually entering water bodies where they can have harmful effects on organisms and can result in ecological damage. To determine the toxicological risk induced by this type of eflluents, eight metals and 11 pharmaceuticals were quantified, in effluent from a hospital. Developmental effects, teratogenesis and oxidative stress induction were evaluated in two bioindicator species: Xenopus laevis and Lithobates catesbeianus. FETAX (frog embryo teratogenesis assay-Xenopus) was used to obtain the median lethal concentration (LC₅₀), effective concentration inducing 50% malformation (EC₅₀), teratogenic index (TI), minimum concentration to inhibit growth (MCIG), and the types of malformation induced. Twenty oocytes in midblastula transition were exposed to six concentrations of effluent (0.1, 0.3, 0.5, 0.7, 0.9, 1%) and negative and positive (6-aminonicotinamide) controls. After 96 h of exposure, diverse biomarkers of oxidative damage were evaluated: hydroperoxide content, lipid peroxidation, protein carbonyl content, and the antioxidant enzymes superoxide dismutase and catalase. TI was 3.8 in X. laevis and 4.0 in L. catesbeianus, both exceed the value in the FETAX protocol (1.2), indicating that this effluent is teratogenic to both species. Growth inhibition was induced as well as diverse malformation including microcephaly, cardiac and facial edema, eye malformations, and notochord, tail, fin and gut damage. Significant differences relative to the control group were observed in both species with all biomarkers. This hospital effluent contains contaminants which represents a toxic risk, since these substances are teratogenic to the bioindicators used. The mechanism of damage induction may be associated with oxidative stress.

High contamination in the areas surrounding abandoned mines and mining activities: An impact assessment of the Dilala, Luilu and Mpingiri Rivers, Democratic Republic of the Congo

Abandoned mines and mining activities constitute important sources of toxic metals and Rare Earth Elements (REEs) affecting surrounding environmental compartments and biota. This study investigates the contamination degree and distribution of toxic metals and REEs in contrasting sediment, soil and plant samples surrounding rivers in the African copperbelt area characterized by the presence of numerous abandoned mines, artisanal and industrial mining activities. ICP-MS results highlighted the highest concentration of Cu, Co and Pb in sediments reaching values of 146,801, 18,434 and 899 mg kg^-1, respectively. In soil, the values of 175,859, 21,134 and 1164 mg kg^-1 were found for Cu, Co and Pb, respectively. These values are much higher than the sediment guidelines for the protection of aquatic life and international soil clean-up standards. Enrichment factor and geoaccumulation index results indicated important contribution of mining activities to the study sites pollution in addition to natural background. Highest metal accumulation in leaves of Phalaris arundinacea L., was observed, reaching values of 34,061, 5050 and 230 mg kg^-1 for Cu, Co, and Pb, respectively. The ∑REE concentration reached values of 2306, 733, 2796 mg kg^-1 in sediment, soil and plant samples, respectively. The above results were combined with geographical information including satellite imagery, hydrography and mining concessions. Maps were produced to present the results in a comprehensive and compelling visual format. The results will be disseminated through an innovative mapping online platform to simplify access to data and to facilitate dialogue between stakeholders.

Consumption-based approach for pharmaceutical compounds in a large hospital

Hospital wastewater contains a great variety of pharmaceutical compounds (PhCs), mainly due to excretion by patients. These PhCs, called emerging pollutants, are not fully eliminated in treatment plants, and are consequently detected in various environmental matrices, contributing to bacterial resistance and adverse environmental impacts on water resources. This study explores a consumption-based approach to predict the contribution of PhCs to a Brazilian hospital's wastewater. This approach identifies the consumption of major pharmaceutical classes in the studied hospital. Overall, this approach demonstrates a unique opportunity to screen PhCs used in hospitals and identify priority pollutants in hospital wastewater.

Accumulation of toxic metals and organic micro-pollutants in sediments from tropical urban rivers, Kinshasa, Democratic Republic of the Congo

The increasing contamination of fresh water resource by toxic metals and Persistence Organic Pollutants (POPs) is a major environmental concern globally. In the present investigation, surface sediments collected from three main rivers named, Makelele, Kalamu and Nsanga, draining through the city of Kinshasa, Democratic Republic of the Congo, were characterized for grain size, organic matter, toxic metals, POPs (including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs)), and polycyclic aromatic hydrocarbons (PAHs). Furthermore, enrichment factor (EF) and geoaccumulation index (Igeo) were performed to determine metal source and pollution status. The results highlighted high concentration of toxic metals in all sediment samples, reaching the values (mg kg^-1) of 325 (Cu), 549 (Zn), 165 (Pb) and 1.5 (Cd). High values of PCBs and OCPs were detected in sediment samples, e.g. in Makelele river, PCB values ranged from 0.9 to 10.9 with total PCBs (∑7 PCBs × 4.3): 169.3 μg kg^-1; OCPs from 21.6 to 146.8 with ∑OCPs: 270.6 μg kg^-1. The PBDEs concentrations were higher in investigated rivers comparatively with values detected in many rivers from Sub-Saharan Africa. The ΣPAHs value ranged from 22.6 to 1011.9 μg kg^-1. River contamination may be explained by local intense domestic activities, urban and agricultural runoff, industrial and hospital wastewaters discharge into the rivers without prior treatment. This research provides not only a first baseline information on the extent of contamination in this tropical ecosystem but also represents useful tools incorporated to evaluate sediment quality in the river receiving systems which can be applied to similar aquatic environments.

Antibiotic resistant Pseudomonas spp. in the aquatic environment: A prevalence study under tropical and temperate climate conditions

Microbial populations which are resistant to antibiotics are an emerging environmental concern with potentially serious implications for public health. Thus, there is a growing concern in exploring the occurrence of antibiotic resistance in the environment with no limitations to the factors that contribute to their emergence. The aquatic environment is considered to be a hot-spot for the acquisition and spread of antibiotic resistance due to pollution with emerging contaminants derived from anthropogenic activities. In this study, we report on the isolation and characterization of 141 Pseudomonas spp. from aquatic sediments receiving partially (un)treated hospital and communal effluents from three distinct geographical locations: Democratic Republic of the Congo (DRC), India (IN), and Switzerland (CH). P. putida (42%) and P. aeruginosa (39%) were the dominant Pseudomonas species. The highest frequency of antibiotic resistance against eight anti-pseudomonas agents was found among IN isolates (35-60%), followed by DRC (18-50%) and CH (12-54%). CTX-M was the most frequent β-lactamase found in CH (47% of isolates), while VIM-1 was dominant in isolates from DRC (61%) and IN (29%). NDM-1 was found in 29% of the total IN isolates and surprisingly also in 6% of CH isolates. Chromosomally-encoded efflux mechanisms were overexpressed in P. aeruginosa isolates from all three geographic locations. In vitro conjugative transfers of antibiotic resistance plasmids occurred more frequently under tropical temperatures (30 and 37 °C) than under temperate conditions (10 °C). The presence of Extended Spectrum β-lactamases (ESBLs) and Metallo β-lactamases (MBLs) in the isolates from environmental samples has important implications for humans who depend on public water supply and sanitation facilities. To our knowledge, this is the first study to demonstrate a comparison between treated/untreated effluents from urban and hospital settings as a source of microbial resistance by evaluating the aquatic ecosystems sediments from tropical and temperate climate conditions. Taken together, our findings demonstrate a widespread occurrence of antibiotic resistance in aquatic ecosystems sediments receiving untreated/treated wastewater and how these contemporary sources of contamination, contribute to the spread of microbial resistance in the aquatic environment. This research presents also useful tools to evaluate sediment quality in the receiving river/reservoir systems which can be applied to similar environments.

Microbiological quality of water in a city with persistent and recurrent waterborne diseases under tropical sub-rural conditions: The case of Kikwit City, Democratic Republic of the Congo

The availability of safe drinking water in sub-Saharan countries remains a major challenge because poor sanitation has been the cause of various outbreaks of waterborne disease due to the poor microbiological quality of water used for domestic purposes. The faecal indicator bacteria (FIB) used in the present study included Escherichia coli (E. coli) and Enterococcus (ENT). FIB and aerobic mesophilic bacteria (AMB) were quantified during July 2015 (dry season) and November 2015 (rainy season) in order to assess the quality of drinking water from wells (n=3; P1-P3), and two rivers, the River Lukemi (RLK, n=3) and River Luini (RLN, n=2) in the city of Kikwit, which is located in the province of Kwilu in the Democratic Republic of the Congo. Kikwit is well known for its outbreaks of persistent and recurrent waterborne diseases including Entamoeba, Shigella, typhoid fever, cholera, and Ebola Viral Hemorrhagic Fever. Consequently, E. coli, ENT, and AMB were quantified in water samples according to the standard international methods for water quality determination using the membrane filtration method. The FIB characterization was performed for human-specific Bacteroides by PCR using specific primers. The results obtained revealed high FIB concentrations in river samples collected during both seasons. For example, E. coli respectively reached 4.3×10⁴ and 9.2×10⁴ CFU 100mL^-1 in the dry season and the wet season. ENT reached 5.3×10³ CFU 100mL^-1 during the dry season and 9.8×10³ CFU 100mL^-1 in the wet season. The pollution was significantly worse in the wet season compared to the dry season. Surprisingly, no faecal contamination was observed in well water samples collected in the dry season while E. coli and ENT were detected in all wells in the wet season with values of 6, 7, and 11CFUmL^-1 for E. coli in wells P1-P3, respectively and 3, 5, 9 CFU mL^-1for ENT in the same wells. Interestingly, the PCR assays for human-specific Bacteroides HF183/HF134 indicated that 97-100% captured in all analyses of isolated FIB were of human origin. The results indicate that contamination of E. coli, ENT, and AMB in the studied water resources increases during the wet season. This study improves understanding of the microbiological pollution of rivers and wells under tropical conditions and will guide future municipal/local government decisions on improving water quality in this region which is characterised by persistent and recurrent waterborne diseases. Although the epidemiology can be geographically localised, the effects of cross border transmission can be global. Therefore, the research results presented in this article form recommendations to municipalities/local authorities and the approach and procedures can be carried out in a similar environment.

The impact of hospital and urban wastewaters on the bacteriological contamination of the water resources in Kinshasa, Democratic Republic of Congo

Although the United Nations General Assembly recognized in 2010 the right to safe and clean drinking water and sanitation as a human right that is essential to the full enjoyment of life and all other human rights, the contamination of water supplies with faecal pathogens is still a major and unsolved problem in many parts of the world. In this study, faecal indicator bacteria (FIB), including Escherichia coli (E. coli) and Enterococcus (ENT), were quantified over the period of June/July 2014 and June/July 2015 to assess the quality of hospital effluents (n = 3: H1, H2 and H3) and of rivers receiving wastewaters from the city of Kinshasa, Democratic Republic of Congo. The water and sediment samples from the river-receiving systems were collected in, upstream and downstream of the hospital outlet pipe (HOP) discharge. The analysis of E. coli and ENT in water and sediment suspension was performed using the cultural membrane filter method. The FIB characterization was performed for general E. coli, Enterococcus faecalis(E. faecalis) and human-specific Bacteroides by PCR using specific primers. The results revealed very high FIB concentration in the hospital effluent waters, with E. coli reaching the values of 4.2 × 10(5), 16.1 × 10(5) and 5.9 × 10(5) CFU 100 mL(-1), for the hospital effluents from H1, H2, and H3, respectively; and Enterococcus reaching the values of 2.3 × 10(4), 10.9 × 10(4) and 4.1 × 10(4) CFU 100 mL(-1), respectively. Interestingly, the FIB levels in the water and sediment samples from river-receiving systems are spatially and temporally highly variable and present in some samples with higher values than the hospital effluents. The PCR assays for human-specific Bacteroides HF183/HF134 further indicate that more than 98% of bacteria were from human origin. The results of this research therefore confirm the hypothesis of our previous studies, indicating that in developing countries (e.g., Democratic Republic of Congo and South India), the hospital effluent waters can be a significant source of the deterioration of the bacteriological quality for urban rivers. The approach used in this investigation can be further used to decipher the pollution of water resources by human faecal contamination. The results of this research will help to better understand the microbiological pollution problems in river-receiving systems and will guide municipality decisions on improving the urban water quality.

Leachates draining from controlled municipal solid waste landfill: Detailed geochemical characterization and toxicity tests

Management of municipal solid wastes in many countries consists of waste disposal into landfill without treatment or selective collection of solid waste fractions including plastics, paper, glass, metals, electronic waste, and organic fraction leading to the unsolved problem of contamination of numerous ecosystems such as air, soil, surface, and ground water. Knowledge of leachate composition is critical in risk assessment of long-term impact of landfills on human health and the environment as well as for prevention of negative outcomes. The research presented in this paper investigates the seasonal variation of draining leachate composition and resulting toxicity as well as the contamination status of soil/sediment from lagoon basins receiving leachates from landfill in Mpasa, a suburb of Kinshasa in the Democratic Republic of the Congo. Samples were collected during the dry and rainy seasons and analyzed for pH, electrical conductivity, dissolved oxygen, soluble ions, toxic metals, and were then subjected to toxicity tests. Results highlight the significant seasonal difference in leachate physicochemical composition. Affected soil/sediment showed higher values for toxic metals than leachates, indicating the possibility of using lagoon system for the purification of landfill leachates, especially for organic matter and heavy metal sedimentation. However, the ecotoxicity tests demonstrated that leachates are still a significant source of toxicity for terrestrial and benthic organisms. Therefore, landfill leachates should not be discarded into the environment (soil or surface water) without prior treatment. Interest in the use of macrophytes in lagoon system is growing and toxic metal retention in lagoon basin receiving systems needs to be fully investigated in the future. This study presents useful tools for evaluating landfill leachate quality and risk in lagoon systems which can be applied to similar environmental compartments.

Hospital Effluents Are One of Several Sources of Metal, Antibiotic Resistance Genes, and Bacterial Markers Disseminated in Sub-Saharan Urban Rivers

Data concerning the occurrence of emerging biological contaminants such as antibiotic resistance genes (ARGs) and fecal indicator bacteria (FIB) in aquatic environments in Sub-Saharan African countries is limited. On the other hand, antibiotic resistance remains a worldwide problem which may pose serious potential risks to human and animal health. Consequently, there is a growing number of reports concerning the prevalence and dissemination of these contaminants into various environmental compartments. Sediments provide the opportunity to reconstruct the pollution history and evaluate impacts so this study investigates the abundance and distribution of toxic metals, FIB, and ARGs released from hospital effluent wastewaters and their presence in river sediments receiving systems. ARGs (bla TEM, bla CTX-M, bla SHV, and aadA), total bacterial load, and selected bacterial species FIB [Escherichia coli, Enterococcus (ENT)] and species (Psd) were quantified by targeting species specific genes using quantitative PCR (qPCR) in total DNA extracted from the sediments recovered from 4 hospital outlet pipes (HOP) and their river receiving systems in the City of Kinshasa in the Democratic Republic of the Congo. The results highlight the great concentration of toxic metals in HOP, reaching the values (in mg kg(-1)) of 47.9 (Cr), 213.6 (Cu), 1434.4 (Zn), 2.6 (Cd), 281.5 (Pb), and 13.6 (Hg). The results also highlight the highest (P < 0.05) values of 16S rRNA, FIB, and ARGs copy numbers in all sampling sites including upstream (control site), discharge point, and downstream of receiving rivers, indicating that the hospital effluent water is not an exclusive source of the biological contaminants entering the urban rivers. Significant correlation were observed between (i) all analyzed ARGs and total bacterial load (16S rRNA) 0.51 to 0.72 (p < 0.001, n = 65); (ii) ARGs (except bla TEM) and FIB and Psd 0.57 < r < 0.82 (p < 0.001, n = 65); and (iii) ARGs (except bla TEM) and toxic metals (Cd, Cr, Cu, and Zn) 0.44 to 0.72, (p < 0.001, n = 65). These findings demonstrate that several sources including hospital and urban wastewaters contribute to the spread of toxic metals and biological emerging contaminants in aquatic ecosystems.

Occurrence of Antibiotic Resistance Genes and Bacterial Markers in a Tropical River Receiving Hospital and Urban Wastewaters

The occurrence of emerging biological contaminants including antibiotic resistance genes (ARGs) and Faecal Indicator Bacteria (FIB) is still little investigated in developing countries under tropical conditions. In this study, the total bacterial load, the abundance of FIB (E. coli and Enterococcus spp. (ENT)), Pseudomonas spp. and ARGs (blaTEM, blaCTX-M, blaSHV, blaNDM and aadA) were quantified using quantitative PCR in the total DNA extracted from the sediments recovered from hospital outlet pipes (HOP) and the Cauvery River Basin (CRB), Tiruchirappalli, Tamil Nadu, India. The abundance of bacterial marker genes were 120, 104 and 89 fold higher for the E. coli, Enterococcus spp. and Pseudomonas spp., respectively at HOP when compared with CRB. The ARGs aadA and blaTEM were most frequently detected in higher concentration than other ARGs at all the sampling sites. The ARGs blaSHV and blaNDM were identified in CRB sediments contaminated by hospital and urban wastewaters. The ARGs abundance strongly correlated (r ≥ 0.36, p < 0.05, n = 45) with total bacterial load and E. coli in the sediments, indicating a common origin and extant source of contamination. Tropical aquatic ecosystems receiving wastewaters can act as reservoir of ARGs, which could potentially be transferred to susceptible bacterial pathogens at these sites.

Hospital and urban effluent waters as a source of accumulation of toxic metals in the sediment receiving system of the Cauvery River, Tiruchirappalli, Tamil Nadu, India

Hospital and urban effluents contain a variety of toxic and/or persistent substances in a wide range of concentrations, and most of these compounds belong to the group of emerging contaminants. The release of these substances into the aquatic ecosystem can lead to the pollution of water resources and may place aquatic organisms and human health at risk. Sediments receiving untreated and urban effluent waters from the city of Tiruchirappalli in the state of Tamil Nadu, India, are analyzed for potential environmental and human health risks. The sediment samples were collected from five hospital outlet pipes (HOP) and from the Cauvery River Basin (CRB) both of which receive untreated municipal effluent waters (Tiruchirappalli, Tamil Nadu, India). The samples were characterized for grain size, organic matter, toxic metals, and ecotoxicity. The results highlight the high concentration of toxic metals in HOP, reaching values (mg kg(-1)) of 1851 (Cr), 210 (Cu), 986 (Zn), 82 (Pb), and 17 (Hg). In contrast, the metal concentrations in sediments from CRB were lower than the values found in the HOP (except for Cu, Pb), with maximum values (mg kg(-1)) of 75 (Cr), 906 (Cu), 649 (Zn), 111 (Pb), and 0.99 (Hg). The metal concentrations in all sampling sites largely exceed the Sediment Quality Guidelines (SQGs) and the Probable Effect Concentration (PEC) for the Protection of Aquatic Life recommendation. The ecotoxicity test with ostracods exposed to the sediment samples presents a mortality rate ranging from 22 to 100 % (in sediments from HOP) and 18-87 % (in sediments from CRB). The results of this study show the variation of toxic metal levels as well as toxicity in sediment composition related to both the type of hospital and the sampling period. The method of elimination of hospital and urban effluents leads to the pollution of water resources and may place aquatic organisms and human health at risk.

Trace metal distributions in the sediments from river-reservoir systems: case of the Congo River and Lake Ma Vallée, Kinshasa (Democratic Republic of Congo)

The contamination of drinking water resources by toxic metals is a major problem in many parts of the world, particularly in dense populated areas of developing countries that lack wastewater treatment facilities. The present study characterizes the recent evolution with time of some contaminants deposited in the Congo River and Lake Ma Vallée, both located in the vicinity of the large city of Kinshasa, capital of Democratic Republic of Congo (DRC). Physicochemical parameters including grain size distribution, organic matter and trace element concentrations were measured in sediment cores sampled from Congo River (n = 3) and Lake Ma Vallée (n = 2). The maximum concentration of trace elements in sediment profiles was found in the samples from the sites of Pool Malebo, with the values of 107.2, 111.7, 88.6, 39.3, 15.4, 6.1 and 4.7 mg kg(-1) for Cr, Ni, Zn, Cu, Pb, As and Hg, respectively. This site, which is characterized by intense human activities, is especially well known for the construction of numerous boats that are used for regular navigation on Congo River. Concerning Lake Ma Vallée, the concentration of all metals are generally low, with maximum values of 26.3, 53.6, 16.1, 15.3, 6.5 and 1.8 mg kg(-1) for Cr, Ni, Zn, Cu, Pb and As, respectively. However, the comparison of the metal profiles retrieved from the different sampled cores also reveals specific variations. The results of this study point out the sediment pollution by toxic metals in the Congo River Basin. This research presents useful tools for the evaluation of sediment contamination of river-reservoir systems.

Trace metals and persistent organic pollutants in sediments from river-reservoir systems in Democratic Republic of Congo (DRC): Spatial distribution and potential ecotoxicological effects

This paper discusses the occurrence and spatial distribution of metals and persistent organic pollutants (POPs: including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), Polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in sediments from a river-reservoir system. Surface sediments were sampled from thirteen sites of the Congo River Basin and Lake Ma Vallée, both situated in the vicinity of the capital city Kinshasa (Congo Democratic Republic). Sediment qualities were evaluated using toxicity test based on exposing Ostracods to the sediment samples. The highest metal concentrations were observed in sediments subjected to anthropogenic influences, urban runoff and domestic and industrial wastewaters, discharge into the Congo River basin. Ostracods exposed to the sediments resulted in 100% mortality rates after 6d of incubation, indicating the ultimate toxicity of these sediments as well as potential environmental risks. The POPs and PAHs levels in all sediment samples were low, with maximum concentration found in the sediments (area of pool Malebo): OCP value ranged from 0.02 to 2.50 with ∑OCPs: 3.3μgkg(-1); PCB ranged from 0.07 to 0.99 with Total PCBs (∑7×4.3): 15.31μgkg(-1); PAH value ranged from 0.12 to 9.39 with ∑PAHs: 63.89μgkg(-1). Our results indicate that the deterioration of urban river-reservoir water quality result mainly from urban stormwater runoff, untreated industrial effluents which discharge into the river-reservoirs, human activities and uncontrolled urbanization. This study represents useful tools incorporated to evaluate sediment quality in river-reservoir systems which can be applied to similar aquatic environments.