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In recent years, land use related to anthropogenic activities has contributed to high surface water contamination. During the last decade, Lake Toho, in the Republic of Benin, has suffered anthropogenic pollution by the use of fertilizers from farmers around the lake. We assessed the mobility and bioavailability of phosphorus in cultivated soils around the lake to detect the extent of the contamination. The results showed that the cultivated soils around Lake Toho are weakly acidic or even basic with water pHs between 6.25 and 8.3. The humidity of cultivated soils varies from 1% to 38% on different horizons. The content of organic matter is ranged from 40.30% to 49.70%. The total phosphorus concentration ranged from 1049.74 μg.g-1 to 28436.52 μg.g-1 with a high rate of enrichment at the 30 cm horizon. The high contents of total phosphorus recorded at the superficial horizon were due to the use of fertilizers to amend the soil. All forms of phosphorus are represented (P-L, P-Fe, P-Ca, P-Al, and P-OM). The organic fraction predominates on the upper layer of the soil except for sites located outside crop fields. The strong correlation between the Total phosphorus (TP), the (Pr), mobile phosphorus (P-L), and the to organic matter-bound Phosphorus (P-OM) showed that the high phosphorus contents at the upper horizon of the soil were due not only to the anthropogenic contribution but also to the source rock. The remarkable presence of phosphorus in the P-L and P-MO fractions poses a risk of phosphorus transport to the lake. This can lead to eutrophication which can cause the death of fish and harmful toxins development.

Introduction: Because of the specificity of their care activities, hospital wastewater contains various contaminants such as germs, disinfectants, metals, pharmaceuticals and chemical reagents, potentially infectious or toxic, which can be harmful to living organisms, or create ecological damage. This study aimed to analyze the quality of wastewaters produced by university hospitals of Cotonou in Benin. Methods: We conduct an analytical cross-sectional study including 30 wastewater samples from selected hospitals. An analysis of variance was performed at the significance level of 0.05. Results: Microbiological analysis showed the presence of germs such as total coliform types, faecal coliforms, fecal streptococcus, staphylococcus, yeasts and Clostridium perfringens in hospital wastewater samples. There was a significant difference (p < 0.05) in the microbial loads of various germs, except staphylococcus, between hospitals. With regard to the physicochemical parameters, only the conductivity complied with the standards for the discharge of wastewater into the environment. A significant difference was noted between hospitals, for the electrical conductivity of wastewater (p < 0.05). The average levels of metals detected in the wastewaters were in line with Benin’s standards. There was no difference between the average concentrations of metals except for copper (p < 0.05). Conclusion: The wastewater produced by the university hospitals of Cotonou is of poor quality and therefore requires adequate prior treatment before discharge into the environment.

Les effluents générés par les activités hospitalières présentent un danger potentiel pour la santé et l’environnement. L’objectif de cette étude était d’étudier la qualité physico-chimique et toxicologique des effluents produits par les Centres Hospitaliers et Universitaires du département du Littoral. Il s’agissait d’une étude transversale descriptive et analytique sur 60 prélèvements d’effluents hospitaliers provenant des stations d’épuration et des fosses septiques. Les échantillons ont été prélevés dans des bouteilles en plastique de 1,5 litre. Les valeurs moyennes des paramètres avec leurs déviations standards ont été calculées. Une analyse en composante principale a été réalisée. Les paramètres physico-chimiques mesurés et comparés aux normes de rejets des polluants dans l’environnement montraient qu’en dehors du pH, de la température et de la conductivité qui étaient conformes aux normes, tous les autres paramètres présentaient des valeurs supérieures aux normes de rejet. Le potentiel hydrogène, la température et la conductivité mesurés sont respectivement en moyenne de 7,14 ; 24,52 °C et 1243,37 μS/Cm. Les teneurs moyennes en oxygène dissous, en ammonium et en phosphore sont respectivement de 1,29 mg/L, 47,21 mg/L et 33,18 mg/L. La demande biochimique en oxygène est de 86,33 mgO2/L et la demande chimique en oxygène de 164,54 mgO2/L. Les concentrations moyennes du plomb et du cadmium étaient respectivement de 0,53 mg/L et 0,08 mg/L. Ces effluents présentent donc des risques sanitaires et environnementaux. Il apparait alors plus que nécessaire de développer des méthodes de traitement de ces effluents avant leur rejet dans le milieu naturel.Mots clés : Effluents hospitaliers, qualité chimique, risques sanitaires et environnementaux, Bénin. English Title: Physicochemical and toxicological characterization of the effluents of the Hospital and University Centers of the Littoral Department of BeninEffluents generated by hospital activities present a potential danger to health and the environment. The objective was to study the physico-chemical and toxicological quality of the effluents produced by the Hospital and University Centers of the Littoral Department. It was a descriptive and analytical cross-sectional study of 60 samples of hospital effluents from sewage treatment plants and septic tanks. Samples were taken from 1.5 liter plastic bottles. The average values of the parameters with their standard deviations were calculated. A principal component analysis was performed. The physicochemical parameters measured and compared to environmental pollutant release standards showed that, except for the pH, temperature and conductivity that were in compliance with the standards, all other parameters had values that exceeded rejection. The hydrogen potential, the temperature and the conductivity measured are, on average, 7.14, 24.52 °C and 1243.37 μS/cm. The average dissolved oxygen, ammonium and phosphorus contents are respectively 1.29 mg/L, 47.21 mg/L and 33.18 mg/L. The biochemical oxygen demand is 86.33 mgO2/L and the chemical oxygen demand is 164.54 mgO2/L. Mean concentrations of lead and cadmium were 0.53 mg/L and 0.08 mg/L, respectively. These effluents therefore present health and environmental risks. It appears then more than necessary to develop methods of treating these effluents before their release into the natural environment.Keywords: Hospital effluents, chemical quality, health and environmental risks, Benin.

Introduction: The effluents generated by hospital activities pose a potential danger to health and the environment. This study aimed to study the microbiological quality of the effluents produced by the university and hospital centres of Littoral department. Methods: This was a descriptive cross-sectional study of 60 samples of hospital effluents from sewage treatment plants and septic tanks carried out during the period from April to June 2019. Samples at the station were made at the entrance and exit of the station. Samples for microbiological analysis were collected in pre-sterilized 500 mL glass bottles. Samples were kept between at 2°C - 8°C and in the dark to ensure satisfactory preservation. ANOVA one-way analysis of variance was performed for each microbiological parameter and principal component analysis (PCA) was also performed. Results: The bacteriological analyses carried out on the 60 samples taken showed a significant microbiological load. In fact, the bacteriological parameters measured and compared to the pollutant release standards in the environment show that the number of germs identified is above the recommended guideline values. The average values for total coliforms, faecal coliforms, faecal streptococci and staphylococci were: 3.91 × 105 UFC/100 mL, 0.52 × 105 UFC/100 mL, 3.92 × 105 UFC/100 mL and 1.36 × 105 UFC/100 mL, respectively. The most isolated bacteria were: Klebsiella pneumoniae, Klebsiella oxytoca, Escherichia coli, Enterococcus faecalis, Enterobacter cloacae, Pseudomonas horizyhabitans, Staphylococcus aureus and Staphylococcus saprophyticus. Most strains were resistant to at least 3 families of antibiotics (beta-lactams, aminoglycosides and fluoroquinolones). Conclusion: These effluents therefore present health and environmental risks. It is of utmost importance to develop methods for the treatment of these effluents before their release into the natural environment.

BackgroundLiquid 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.MethodsIt 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: ResultsIn 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.ConclusionThese 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.

Polybrominated diphenyl ethers (PBDEs) derived from e-waste dismantling, tend to easily bioaccumulate in vegetables. In this study, an optimized sample pretreatment method based on graphene oxide (GO) dispersed acid silica gel was used to determine PBDEs levels in vegetables. The recovery efficiency of the optimized method ranged between 90.3%–107.5% with the detection limit (LOD) being within 0.17–1.8 ng g−1. Vegetable samples were grown nearby an e-waste recycling plant in Nanjing, China, and analyzed using the optimized method. The concentrations of ΣPBDEs in the samples ranged from 12.1 to 20.1 ng g−1. This study developed an optimized sample pretreatment method to determine PBDEs in vegetables nearby e-waste contaminated sites and provides insights on the potential risks derived from e-waste dismantling to the surrounding environment.

Limited information about the sludge quality is a major constraint for its usage and proper disposal. This study investigated the occurrence of 49 elements in sludge from 11 wastewater treatment plants (WWTPs) in Chongqing and Xiamen cities of China. The concentration of 46-detected elements ranged from 16.2 μg kg−1 (Pt) to 55.0 g kg−1 (Al) on dry solid basis in the sludge. The enrichment factor of most of the elements was > 1.5, indicating their possible anthropogenic origin. The precious metals had considerably higher enrichment factor ranging from 56.3 to 200,000. Principal component analysis clustered the samples from Chongqing and Xiamen separately to suggest strong spatial variations. Contamination factor, pollution loading index, and integrated pollution degree were calculated to evaluate the elemental pollution risk. The pollution loading index indicated unpolluted to highly polluted levels of the elements in the sludge. In addition, results from the ecotoxicological risk index showed an individual low to very high ecotoxicological risk posed by eight metal(loid)s (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in the WWTPs.

The aim of this study was to quantify the removal of halogenated pollutants (using triclosan as a model pollutant) from aqueous solution by zero-valent iron coupled with a weak magnetic field. We determined the removal efficiency of triclosan from a sodium sulfate solution at different pH values under both aerobic and anaerobic conditions. The removal of triclosan followed pseudo-first-order kinetics in both the presence and absence of a weak magnetic field. The calculated rate constants indicated higher removal efficiencies of triclosan under the aerobic condition compared to the anaerobic condition. In addition, increase of triclosan removal from acidic solutions was achieved with the assistance of weak magnetic field. X-ray diffraction and X-ray photoelectron spectroscopy analysis indicated that FeO(OH) and Fe3O4 were the main aerobic transformation products, suggesting that the zero-valent iron surfaces were completely oxidized. The aerobic and anaerobic transformation products of triclosan were analyzed by liquid chromatography tandem mass spectrometry. The results indicated that the application of a weak magnetic field could be an efficient and cheap treatment process to improve the removal of halogenated pollutants by zero-valent iron, which may be developed for future use.

Sulfamethoxazole (SMX) is a common medicine prescribed to treat infections. Due to vast use, SMX has been detected in different parts of the world. Hence, it has become a high risk because of its long term persistence with high biological activity in the ecosystem. Therefore, it is necessary to understand the mechanism of SMX degradation in different genus of bacteria, which is presently unclear. In the present study, degradation of 5 mg L −1 SMX was studied in three isolated pure bacterial cultures, Ochrobactrum sp. SMX-PM1-SA1, Labrys sp. SMX-W1-SC11 and Gordonia sp. SMX-W2-SCD14 and results showed up to 45.2%, 62.2% and 51.4% degradation, respectively within 288 h. Additionally, strain SA1 and strain SCD14 showed up to 66.2% and 69.2% of 4-aminophenol degradation at an initial concentration of 5 mg L −1 within 216 h whereas Labrys sp. SMX-W1-SC11 completely degraded 4-aminophenol at the same concentration within 120 h. Moreover, all three pure bacteria also completely degraded 3-amino-5-methylisoxazole at initial concentration of 4 mg L −1 within 120 h. Furthermore, gas chromatography-mass spectrometry and quadrupole time-of-flight mass spectrometry analysis results revealed that 3-amino-5-methylisoxazole, 4-aminophenol and hydroquinone were the three main by-products of SMX catabolism. In addition, cell free extracts of both Labrys sp. SMX-W1-SC11 and Gordonia sp. SMX-W2-SCD14 showed hydroquinone dioxygenase activity. Besides, all three bacterial strains showed resistance to different heavy metals. Moreover, all three pure bacterial cultures also showed positive chemotactic response toward 3-amino-5-methylisoxazole and hydroquinone based on the drop plate assay. The results of this study recommend these microorganisms for bioremediation of SMX contaminated sites.

Remediation of organochlorine pesticides (OCPs)-contaminated soils is urgently required especially in China. Surfactants have emerged as reliable and efficient co-solvent for the treatment of hardly soluble organic pollutants in contaminated soil. Here, we report the use of TritonX-100 (TX-100) in advanced oxidation under electrokinetic technology (EK) for OCPs removal from a historically contaminated soil from a former pharmaceutical industrial wasteland. Result shows that TX-100 (10%) played a key role in soil remediation. In effect, after a treatment period of 15 days, pollutants washed ranged from 50.68% (4,4'-DDT) to 76.07% (HCB), when TX-100 was used as the electrolyte (EK-TX-100). A simple advanced oxidation of the soil using sodium persulfate (PS) under EK approach (EK-PS) was limited to achieve good removal efficiency of the pollutants; as the result of OCPs' hardly dissolvable nature. The achieved removal efficiency were comprised between 22.62% (2,4-DDT) and 55.78% (1,2,4,5-TCB). With the application of TX-100 as co-solvent (EK-TX-100/PS), the pollutants removal efficiency significantly improved (p 0.05). The treatment efficiency was shifted and up to 88.05% (1,2,4-TCB) was achieved, while the lowest removal efficiency was 56.36% (4,4'-DDE). We come to the conclusion that the use of TX-100-enhanced advanced oxidation (EK-TX-100/PS) as a reliable treatment for remediating organochlorine contaminated soil.

Nitrogen contamination remains a severe environmental problem and a major threat to sustainable development worldwide. A systematic analysis of the literature indicates that the partial nitritation-anammox (PN/AMX) process is still actively studied as a viable option for energy-efficient and feasible technology for the sustainable treatment of N- rich wastewaters, since its initial discovery in 1990. Notably, the mainstream PN/AMX process application remains the most challenging bottleneck in AMX technology and fascinates the world's attention in AMX studies. This paper discusses the recent trends and developments of PN/AMX research and analyzes the results of recent years of research on the PN/AMX from lab-to full-scale applications. The findings would deeply improve our understanding of the major challenges under mainstream conditions and next-stage research on the PN/AMX process. A great deal of efforts has been made in the process engineering, PN/AMX bacteria populations, predictive modeling, and the full-scale implementations during the past 22 years. A series of new and excellent experimental findings at lab, pilot and full-scale levels including good nitrogen removal performance even under low temperature (15-10 °C) around the world were achieved. To date, pilot- and full-scale PN/AMX have been successfully used to treat different types of industrial sewage, including black wastewater, sludge digester liquids, landfill leachate, monosodium glutamate wastewater, etc. Supplementing the qualitative analysis, this review also provides a quantitative bibliometrics study and evaluates global perspectives on PN/AMX research published during the past 22 years. Finally, general trends in the development of PN/AMX research are summarized with the aim of conveying potential future trajectories. The current review offers a valuable orientation and global overview for scientists, engineers, readers and decision makers presently focusing on PN/AMX processes.

In this study, the decolorization and degradation of methyl red (MR) by suspended and immobilized cells of Aeromonas jandaei strain SCS5 under anaerobic and aerobic conditions have been investigated. The complete decolorization of MR at a concentration of 100 mg L−1 by A. jandaei strain SCS5 was obtained within 6 h for both anaerobic and aerobic suspended cultures, where the decolorization rate was faster in acidic conditions than basic conditions. The decolorization efficiency under 6 h increased with increasing cell mass of inoculation and decreased with increasing initial dye concentrations. Immobilized cells of A. jandaei strain SCS5 could decolorize MR, and the decolorization rate was significantly enhanced by cells immobilized with mediators such as anthraquinone-2,6-disulphonate and magnetic Fe3O4 nanoparticles compared to immobilized cells only. Moreover, the immobilized bacterial beads with mediators retained high decolorization activity up to more than 10 repeating cycles. UV–visible spectra (200–800 nm) and gas chromatography-mass spectrometry analysis demonstrated that MR was degraded by A. jandaei strain SCS5 through reductive cleavage of azo bond. MR degradation products showed less phytotoxicity against Triticum aestivum and Phaseolus mungo compared to untreated MR. This study has demonstrated that A. jandaei strain SCS5 could be a promising microbiological agent for the removal of azo dyes from the environment.

Soil from a former chemical plant was found to be contaminated with organochlorine compounds (OCs) from aged pesticide residues and underwent surfactant-enhanced electrokinetic remediation (EKR). Tween 80 (TW80) and N,N-Dicarboxymethyl glutamic acid tetrasodium (GLDA) were used to increase the availability of OCs and to enhance oxidation efficiency in the soil under EKR. The results indicate that flushing soil with TW80 increased the removal of persistent OCs from the soil, with 40%–80% removal efficiency. Further, incorporating TW80 with sodium persulfate significantly advanced oxidation and removed 60%–82% of OCs (in both absence and presence of the nZVI reactive barrier) within 10 days. Compared to control treatment, the addition of TW80 improved EKR by 20%–30%. The improvement was attributed to the ability of TW80 to solubilize hardly-soluble compounds and to sustain the activation of persulfate ions (S2O82−) by dissolving metal ions in the soil that would stimulate the production of sulfate radicals (SO4•−) and thus the degradation of pollutants (in the absence of nZVI reactive barrier). Differing from TW80, GLDA’s capacity to solubilize and extract OCs from the soil was much lower and less reliable, averaging around 10% compared to 60% OC-removal for TW80. However, in the absence of oxidant activators from an external source, GLDA was important for sustaining the Fenton reaction. Its inclusion increased pollutant removal from an average of 50%–60%. The addition of the nZVI reactive barrier did not significantly improve remediation within 7 days. These findings suggest that TW80 combined with EKR and advanced oxidation in the presence of the nZVI reactive barrier is the best in situ approach to remediate soils contaminated with OCs from chemical waste of industrial processes.

Limited information about the sludge quality is a major constraint for its usage and proper disposal. This study investigated the occurrence of 49 elements in sludge from 11 wastewater treatment plants (WWTPs) in Chongqing and Xiamen cities of China. The concentration of 46-detected elements ranged from 16.2 μg kg

Biosolids are the treated organic residuals, also known as sewage sludge, which are generated from domestic wastewater treatment plants. It is an organic matter and nutrients [phosphorous (P) and nitrogen (N)]-rich material. Due to these properties, it is has been reported to be a suitable fertilizer or soil amendment which can valuably replace synthesized NPK. Unfortunately, this matter is heavily loaded with inorganic pollutants, namely heavy metals which limit its land application. Here, we evaluated the quality of treated sewage sludge from Wastewater Treatment Plants (WWTP) in the republic of Benin; and assessed the eco-toxicological risks of heavy metals contamination and spreading related to the use of sludge as fertilizer in agriculture. Results revealed a slightly alkaline (pH ≥6.5) and high electrical conductivity (EC >4 mS cm-1) of the sludge. Heavy metals including Cd, Co, Cu, Zn, Ni, Cr, Pb, Fe and Mn contents were at high level: 27.1, 18.6, 777.1, 1271.7, 165.5, 297.0, 131.2, 3184.0 and 394.2 mg kg-1 DM, respectively. Further fractionation of metals showed high mobility of metals classified as follow: Cu > Cd > Pb > Cr > Ni > Fe > Mn > Co > Zn. As a consequence, although the sludge is rich in organic matter and phosphorous, its high value of EC and heavy metals contents, with high mobility do not favor its used in agriculture soils. In addition, metals were enriched in the sludge; meaning that anthropogenic sources, human activities greatly contributed to the accumulation of metals in the sludge.

The disadvantaged areas of South Benin and the Agla district of Cotonou are faced with problems of cyclical floods. These areas of swamps and water reservoirs favor the proliferation of water-borne diseases (diarrhea, cholera, dysentery, typhoid fever, etc.), especially in small children because of the 82.5% population.The aim of our study is to assess the pollution status of these waters in order to draw the attention of the population in general and of the communal officials in particular to the need to promote simple methods of reducing domestic wastewater pollutants.In order to achieve this objective, we collected and analyzed the waste water (EV water, gray water EG) and compared these results with those of the wastewater collector water (ECE) which crosses the Agla district. The physico-chemical parameters of the wastewater were determined in accordance with French standards.The results show that all waters are slightly alkaline and have a high content of organic pollutants (COD and BOD5). The waters of the collector (ECE) and the gray water (EG) have a COD content equal to 1 395 and 1 457 mg/L respectively. Valve water has a higher COD (3 077 mg/L) than the latter. Gray water has high conductivities (2 458 μS/cm). Finally, the presence of fecal enterococci (EV, ECE) which show fecal pollution. On the basis of these results, it can be concluded that the wastewater of the Agla district is polluted and that the waste water and the collector (EV; ECE) are out of class (HC). Gray water varies between class C (Poor quality water) and HC. All of these waters require prior treatment before release into the immediate environment., Les zones déshéritées du Sud Bénin comme le quartier Agla de Cotonou sont confrontées aux problèmes d’inondations cycliques. Ces zones constituées de marécages et de retenues d’eaux favorisent la prolifération des maladies hydriques (diarrhée, choléra, dysenterie, fièvre typhoïde etc…) particulièrement chez les petits enfants à cause des eaux usées domestiques qui y sont déversées par 82,5 % de la population.Notre étude a pour but d’évaluer l’état de pollution de ces eaux afin d’attirer l’attention de la population en générale et des responsables communaux en particulier sur la nécessité de promouvoir des méthodes simples de réduction des polluants des eaux usées domestiques.En vue de l’atteinte de cet objectif, nous avons procédé au prélèvement et à l’analyse des eaux usées (l’eau vanne EV, l’eau grise EG) puis comparé ces résultats à ceux des eaux du collecteur d’eaux usées (ECE) qui traverse le quartier Agla. Les paramètres physico chimiques des eaux usées ont été déterminés conformément aux normes françaises.Les résultats montrent que toutes les eaux sont légèrement alcalines et ont une teneur élevée en polluants organiques (DCO et DBO5). Les eaux du collecteur d’eau (ECE) et les eaux grises (EG) ont respectivement une teneur en DCO égale à 1 395 et 1 457 mg/L. Les eaux vannes ont un taux en DCO (3 077 mg/L) supérieur à ces dernières. Les eaux grises ont des conductivités élevées (2 458 µS/cm). Enfin, on note la présence des Entérocoques fécaux (EV, ECE) qui montrent une pollution fécale. Sur la base de ces résultats, on peut conclure que les eaux usées du quartier Agla sont polluées et que les eaux vannes et du collecteur (EV ; ECE) sont hors classes (HC). Les eaux grises varient entre la classe C (Eau de mauvaise qualité) et HC. Toutes ces eaux nécessitent un traitement préalable avant rejet dans l’environnement immédiat.

Nowadays, sewage sludge and water bodies are subjected to heavy pollution due to rapid population growth and urbanization. Heavy metal pollution represents one of the main challenges threatening our environment and the ecosystem. The present work aims to evaluate the contamination state of the sewage sludge and lake sediments in the Republic of Benin. Twenty metallic elements including 15 rare earth elements (Eu, Sb, Cs, Nd, Pr, Gd, La, Ce, Tb, Sm, Dy, Ho, Eu, Yb, and Lu) and five precious elements (Ag, Au, Pd, Pt, and Ru) were investigated using inductive plasma-mass spectrometry. Results showed broad range concentrations of the elements. Ce, La, and Nd were present in both sediments and sewage sludge at concentrations ranging 5.80–41.30 mg/kg dry matter (DM), 3.23–15.60 mg/kg DM, and 2.74–19.26 mg/kg DM, respectively. Pr, Sm, Gd, Tb, Dy, Eu, Er, Yb, Cs, Ho, and Tm concentrations were lower (0.02–5.94 mg/kg DM). Among precious elements, Ag was detected at the highest concentration in all sites (0.43–4.72 mg/kg DM), followed by Pd (0.20–0.57 mg/kg DM) and Au (0.01–0.57 mg/kg DM). Ru and Pt concentrations were

Industrialization and accelerated population growth have created a huge amount of sewage sludge. Many studies have reported the sewage sludge as a sink of major and trace elements, but less is known about their geochemical fractionations. In order to assess the mobility, the distribution, bioavailability, and toxicity of those elements in sludge, we collected the sewage sludge samples from all the seven wastewater treatment plants in Xiamen City, China. Results revealed a strong spatial variation and the occurrence of 48 elements with concentrations ranging from 1.00×10-2 mg kg-1 (Re) to 9.03×101 g kg-1 (Fe) on the basis of dry sludge weight. Sequential extraction procedure showed that residual and oxidizable fractions were the main geochemical fractions of most studied elements. However, Ca, Mn, Sr, and Ni were mainly bound to acid-exchangeable fractions, while Fe, Zn, Cd, Cr, Co, and V were mainly distributed in the reducible fractions. The contamination factor and risk assessment code indicated that Ni, Cu, Zn, Cd, Cr, Co, Sr, Ca, Mn, Mo, Re, and W were highly mobile with less retention time and exerted high environmental risks through sludge land application. The sludge disposal strategy should consider not only the total concentrations of a broad range of elements but also their bioavailability.

Iron and Manganese contents and parameters including pH, conductivity, and organic matter contents were determined in the sediments of the Okpara dam in Northern Benin. Fifteen samples were collected during a one-month period and analysed in laboratory using the method of sequential extraction of Tessier. The analyses indicated that sediments contained high concentrations in reducible fraction of Iron and relatively high contents of exchangeable fraction, acidhydrolysable fraction and residual fraction of Manganese. The findings of this study confirmed the hypotheses that the meal contents of the sediments were relatively high and varied according to the geochemical phases.

We evaluate the long-term performance of a vegetated drainage ditch (VDD) treating domestic sewage with respect to heavy metal/metalloid (HM/M) accumulation in sediments, plants and water. VDD sediment contained significantly higher macro and trace elements compared to an agricultural ditch (AD) sediment. However, concentrations of HM/Ms in VDD sediment were below the ranges considered toxic to plants. Most HM/Ms were efficiently removed in the VDD, whereby removal efficiencies varied between 11% for Al and 89% for K. Accumulation of HM/Ms varied among species and plant parts, although sequestration by plants represents only a small proportion (1%) of the inflow load. Accumulation of Al, As, Cd, Pb, Cr, Fe and Ni in VDD plants were mostly distributed in the roots, indicating an exclusive strategy for metal tolerance. The opposite was found for Zn, Cu, K, Ca, P, K, Na, N and Mg, which were accumulated either in the stems or leaves. Overall, concentrations of metals in sediment showed significant positive correlations with those in ditch plants. None of the studied species were identified as metal hyper-accumulators (i.e.10,000mgkg

Lab scale and single stage high solid anaerobic digestion of sewage sludge spiked with freshly synthesized nanoscale zero valent iron (nZVI) and commercial iron powder (IP) under mesophilic condition (37±1°C) was performed. The effects of both additives on methane yield, and pharmaceutical and personal care product (PPCP) removal were investigated. Results showed that methane yield was increased by 25.2% and 40.8% in the presence of nZVI (0.1%) and IP (1.6%), respectively. Removal efficiencies of chemical oxygen demand were 54.4% and 66.2% in the presence of nZVI and IP, respectively, which were higher compared to the control group (44.6%). In addition, most PPCPs could be partly or completely removed during the anaerobic digestion process. The application of nZVI and IP showed positive impact on the removal of chlorinated PPCPs (p0.05), but did not show significant impact on other PPCPs (p0.05). Our finding suggests that the application of nZVI and IP in anaerobic digestion could be a promising way to enhance methane yield but had less improvement on PPCP degradation.

In Benin fermented fish (lanhouin) are often considered as food reserved for poor people, so these are commodities considered as by-products of fishing. To get the population to consider fermented fish as first choice food products, we decided to determine the fatty acid and amino acid composition of fermented Scomberomorus tritor. For this, after fermentation and drying of Scomberomorus tritor, gas chromatography coupled with mass spectrometry (GC / MS) and high performance liquid chromatography (HPLC) were used as methods of analysis. The results of these analyzes revealed thirty-five (35) fatty acids, including fifteen (15) saturated fatty acids (SFA), nine (09) monounsaturated fatty acids (MUFA) and eleven (11) polyunsaturated fatty acids (PUFA), and seventeen (17)) amino acids including nine (09) non-essential amino acids and eight (08) essential amino acids counted in fermented Scomberomorus tritor. Therefore, these results show a very large richness in nutrients (fatty acids and amino acids) of the fermented Scomberomorus tritor.

Anaerobic digestion (AD) is one of the most widely used processes to stabilize waste sewage sludge and produce biogas renewable energy. In this study, two different iron nanoparticles [nanoscale zero-valent iron (nZVI) and magnetite (Fe 3 O 4 )] were used in the mesophilic AD processes (37 ± 1 °C) to improve biogas production. In addition, changes of heavy metal (Cd, Co, Cu, Zn, Ni and Cr) speciation during AD of sludge with and without iron nanoparticles have been investigated. Concentrations of metals in the initial sludge were as follows: 63.1, 73.4, 1102.2, 2060.3, 483.9 and 604.1 mg kg −1 (dry sludge basis) for Cd, Co, Cu, Zn, Ni and Cr, respectively. Sequential fractionation showed that metals were predominantly bonded to organic matter and carbonates in the initial sludge. Compared with AD without iron nanoparticles, the application of iron nanoparticles (at dose of 0.5% in this study) showed positive impact not only on biogas production, but also on improvement of metals stabilization in the digestate. Metals were found concentrated in Fe–Mn bound and residual fractions and little was accumulated in the liquid digestate and most mobile fractions of solid digestate (water soluble, exchangeable and carbonates bound). Therefore, iron nanoparticles when properly used, could improve not only biogas yield, but also regulate and control the mobilization of metals during AD process. However, our study also observed that iron nanoparticles could promote the immobilization of phosphorus within the sludge during AD, and more research is needed to fully address the mechanism behind this phenomenon and the impact on future phosphorus reuse.

The treatment of wastewater and removal of pollutants before discharge into natural water reserves, remain a major concern of the 21th century. Many of treatment techniques based on phytoremediation present limits regarding the treatment efficiency. In order to improve the efficiency of nutrients abatement in gray water, the synergy between Thalia geniculata and Crassipes Eichhornia (water hyacinth) was studied. Three treatments: Thalia geniculata (TG), water hyacinth (JE) and the combination of the two [Thalia geniculata and water hyacinth, (TJ)] in three different basins have been setup for the treatment of domestic wastewater. The water physicochemical parameters and nutrients concentrations were determined during the treatment process. After twelve days of treatment, results revealed a remarkable reduction of pollutants (NO3-, NTK and PO43-) in the basins TG and JE, with removal efficiencies of (68.62%, 55.71%, 23.55%) and (53.98%; 39.52%; 89.27%), respectively. As for the treatment combining the two species (TJ), the yield of pollutants abatement was 97.75% for NO3-, 82.83% for NTK and 24.84% for PO43-. An excellent treatment performance of the basin TJ was noticed regarding nitrogen removal against phosphate (PO43-) which was poorly removed. Accordingly, the results indicated an interesting synergistic effect between TG and JE; with the dominance of the TG tendency to remove nutrient (NO3-) from wastewater. The observed synergistic effect of Thalia geniculata and water hyacinth could be effective and promising for the sequestration of nitrogen in domestic wastewater within a couple of days. However, further studies are still needed to better understand the mechanism governing the removal of nitrogen to the detriment of phosphate when combining the two species.

Anaerobic digestion is often used to stabilized and convert organic wastes into methane and biological fertilizer. However, when applied to fecal sludge, it doesn’t yield good methane due to its high content of nitrogen. Here we have conducted anaerobic digestion of fecal sludge in the presence of iron powder (Fe) as electron donor. Results showed that 4822.7 mL CH4 kg-1 was successfully recovered from fecal sludge in the control. The use of Fe in the anaerobic bio-digester remarkably improved methane yield. Indeed, up to 9933.3 mL CH4 kg-1 wet sludge was recovered when Fe is properly used (1 g Fe for 400 g wet weight), compared to 4822.7 mL kg-1 in the control. The concentration of methane in the produced biogas increased from 58.0% in the control to 72.5% and 77.6% in the presence of iron powder, respectively at the dose rate of 0.5 g Fe and 1 g Fe per 400 g wet sludge. COD removal efficiency was also greatly improved. 65.5% of COD was removed when excreta was properly spiked with Fe (1g Fe) against 42.2% in the control. This corresponds to an increasing rate of 23%. Furthermore, the presence of Fe in the digesters considerably reduced the odor by trapping produced sulphur ion and prevent the formation of H2S responsible for the sickening odor.

The treatment of domestic wastewater and the improvement of our living environment is a matter of concern. Less costly methods are to be promoted because of the low financial power of the developing countries. In order to satisfy this requirement, here we have proposed an autonomous system for gray water treatment (SAUTEG) using the macrophytes Thalia geniculata plants. This system is composed of 75 plants/m² and purifying capacity EH equal to 8.7 x10-3 equivalent-inhabitant. Using this system, gray water (catch water: EGo and collectors of wastewater: ECo) were collected and processed (EGT and ECT) and physicochemical parameters of the gray water were determined according to the French standard. There was a significant reduction in organic pollution at the level of EGT and ECT respectively (BOD5: 93.49% - 99.04%, COD: 94.40% - 98.25%, MES: 99.99% - 99,98%), organoleptic parameters (color: 86.50% - 84.63%, Turb: 94.13% - 88.61%), trace metallic elements (Pb: 24.52% - 87.02%, Cd: 11.84% - 21.42%). There was also nutrients removal (NO3-: 96.49% -19.04%, NTK: 94.94% - 100% and PO43-: 14.69% - 55.02%). The treated water was less turbid and lighter. There was a good performance of the system regarding biological parameters (E. coli: 100%; Enterococci: 100% and thermo-tolerant Coli: 99.99%). The values were close to those reported in the literature and some meet the standards of domestic wastewater treatment. Comparative study of the results revealed that the SAUTEG purified the waters from the collector better than the gray water. Thalia geniculata plants, in the system played an important role in the reduction of nitrates and lead in domestic wastewater. This system would therefore contribute to the improvement of the environment. We are looking forward to extending this study to other pollutants and to evaluating the saturation time of the system.