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Dans la perspective d’ameliorer l’acces aux services de base en eau potable, hygiene et assainissement (EHA), le Mali a fait de ce secteur une priorite depuis 2006. Cette etude avait pour objectif de mener une analyse critique du diagnostic de l’acces aux services de base EHA et l’impact des deplaces internes de la crise politique et securitaire de 2012 sur ces services dans la commune de Zan Coulibaly afin de proposer des strategies locales perennes. Les donnees ont ete collectees a travers une fiche de questionnaire semi-structuree, des observations directes sur le terrain et la consultation des documents administratifs. L’enquete a revele que les forages (40%) et les puits traditionnels (28%) etaient les principales sources d’approvisionnement en eau. La collecte de l’eau est une activite exclusivement feminine. Pour traiter l’eau de boisson a domicile, la filtration sur linge etait la technique la plus utilisee (71%). Malgre un contexte pandemique a COVID-19, seulement 24 % des personnes interrogees lavaient les mains au sortir des toilettes et 22% avant de manger. Aussi, 16% des enquetes pratiquaient toujours la defecation a l’air libre. De 2016 a 2020, on note une persistance des maladies diarrheiques et une reapparition des maladies dues aux vers intestinaux. Par ailleurs une eradication du trachome et du cholera a ete observee. Neanmoins, les resultats relatifs au site des deplaces internes de la crise, sont alarmantes. Ces donnees constitueraient une base pour mieux orienter les politiques et les actions futures relatives aux services EHA dans la commune de Zan Coulibaly. To improve the access to the basic water, sanitation and hygiene (WASH) services, Mali has made this sector a priority since 2006. This study aimed to conduct a critical analysis of the diagnosis of access to WASH basic services and the impact of internally displaced people from the political and security crisis of 2012 on these services in the rural commune of Zan Coulibaly in order to propose sustainable local strategies. The data were collected throughout a semi-structured questionnaire form, direct observations on the sites in the nine villages, and the consultation of executive documents. The survey revealed that the drilling (40%) and the traditional wells (28%) were the main sources of water supply. The water collection is an exclusively female activity. To treat drinking water at home, the filtration was the most commonly used technique (71%). Despite a pandemic context of COVID-19, only 24% of respondents washed their hands after leaving the toilet and 22% before eating. Also, 16% of respondents have always defecated in the free air. From 2016 to 2020, we note the persistence of diarrheal diseases and the reappearance of intestinal worm diseases. Otherwise, the trachoma and the cholera were eradicated. Nevertheless, the results relating to the internally displaced people from the crisis are alarming. These data could provide a basis for better guiding the future policies and actions in the provision of WASH services in the rural commune of Zan Coulibaly.

The study aims to investigate the removal of nutrients, organic pollutants and fecal bacteria from greywater while evaluating the growth and yields of lettuce using hydroponic system. Lettuces grow in hydroponic systems irrigated with untreated greywater, and fresh well water, separately. Nutrients, organic pollutants, and fecal bacteria of dishwashing greywater were monitored. Agronomical and microbiological parameters of lettuce were investigated. The results showed that removal efficiencies forammonia (NH4+), nitrate (NO3-), and total phosphorus (TP) were 78 %, 87 % and 56 %, respectively. The organic pollutants removal efficiencies were higher than 50% for Total Suspended Solids (TSS), 5-days Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD). The removal efficiencies are 88.68 % and 81.94 % for E. coli, and fecal coliforms, respectively. The fecal bacteria were not observed in the lettuce leaves. Besides, the lettuces irrigated with greywater produced higher biomass than the ones irrigated with fresh well water. The hydroponic system could be an alternative for greywater treatment and ensuring food security.

It has been reported that persistent cyanide pollution occurs in artisanal small-scale gold mining (ASGM) catchment areas in Burkina Faso. In the present study, logistic regression (LR) and Regress...

The COVID-19 pandemic, which outbroke in Wuhan (China) in December 2019, severely hit almost all sectors of activity in the world as a consequence of the restrictive measures imposed. Two years later, Africa still emerges as the least affected continent by the pandemic. This study analyzed COVID-19 prevalence across African countries through country-level variables prior to clustering. Using Spearman-rank correlation, multicollinearity analysis and univariate filtering, 9 country-level variables were identified from an initial set of 34 variables. These variables relate to socioeconomic status, population structure, healthcare system and environment and the climatic setting. A clustering of the 54 African countries is further carried out through the use of agglomerative hierarchical clustering (AHC) method, which generated 3 distinctive clusters. Cluster 1 (11 countries) is the most affected by COVID-19 (median of 63,508.6 confirmed cases and 946.5 deaths per million) and is composed of countries with the highest socioeconomic status. Cluster 2 (27 countries) is the least affected (median of 4473.7 confirmed cases and 81.2 deaths per million), and mainly features countries with the least socioeconomic features and international exposure. Cluster 3 (16 countries) is intermediate in terms of COVID-19 prevalence (median of 2569.3 confirmed cases and 35.7 deaths per million) and features countries the least urbanized and geographically close to the equator, with intermediate international exposure and socioeconomic features. These findings shed light on the main features of COVID-19 prevalence in Africa and might help refine effectively coping management strategies of the ongoing pandemic.The online version contains supplementary material available at 10.1007/s10668-022-02646-3.

The fate of filter materials and microbial communities during the vermifiltration process were studied for 5 months while treating the concentrated greywater. Four filters were filled with 10 cm gravel of which a layer of medium size gravel (5 cm thickness, aggregate size 20–40 mm) at the bottom and a layer of coarse gravel (5 cm thickness, aggregate size 10–20 mm) at the top, then filled with 20 cm sand (d60 = 0.2 mm, d10 = 0.118 mm). Finally, Vermifilter 1 (VF1), control unit and Vermifilter 2 (VF2), were filled with 40 cm fine sawdust (0.05–5 mm) but Vermifilter 3 (VF3), was filled with 40 cm cow dung (0.05–5 mm). Three filters were inoculated with 200 individuals of Eudrilus eugeniae except for the control unit which was filled with sawdust. Five sampling ports were installed on the wall of the filters at 10 cm intervals with reference to the surface of the top layer. Three of the filters were supplied with concentrated greywater and VF1 was supplied with drinking water at the hydraulic loading rate of 16 L m−2.d−1 on batch basis, i.e., four times a day at 8:00 a.m., 11:00 a.m., 2:00 p.m. and 5:00 p.m. Weekly, samples from influent and effluent, and monthly, samples of filter materials collected via sampling ports, were collected and analyzed.The removal efficiencies of biological oxygen demand (BOD5), total chemical oxygen demand (tCOD), and dissolved chemical oxygen demand (dCOD) of VF2 and VF3 were 5–7% higher than the control unit, but little differences were observed in terms of total suspended solids (TSS). However, the removal efficiencies of nutrients for the control unit was slightly better than VF2 and VF3. The pH and Moisture content (MC) of filter materials increased along the depth, but percentage of volatile solids to total solids (VS/TS) decreased through time due to the high number of microbial communities and earthworms dominating the top layer compared to the bottom. The performance of VF2-sawdust was slightly better than VF3-cow dung to treat concentrated greywater., Highlights • Fate of filter materials and microbial communities during vermifiltration process were studied. • Ratio of volatile solids to total solids decreased during vermifiltration process in filter materials. • The bacteria, actinomycetes and fungi intensified where earthworms dominated. • VF2-Sawdust performed slightly better than the VF3-Cow dung.

Vermifiltration technology using Eudrilus Eugeniae could be an alternative low-cost option for the treatment of urban greywater, which is highly polluted with high concentrations of surfactants, so...

It has been reported that persistent cyanide pollution occurs in artisanal small-scale gold mining (ASGM)-affected catchment areas in Burkina Faso. In the present study, the logistic regression method was employed to identify the factors that influence the spatial distribution of cyanide pollution as well as to predict the cyanide pollution map risk at catchment level. Soil samples were collected from two ASGM sites in the northern Zougnazagmiline (“North”) site and southern Galgouli (“South”) site parts of Burkina Faso, covering areas of 22 km2 and 20 km2, respectively. Free cyanide concentration in each sample was measured. It was shown that the spatial distribution of cyanide was solely controlled by the soil type in Zougnazagmiline and both the soil type and electric conductivity in Galgouli. On the other hand, the cyanidation zones within the two catchments were the places where the highest risk of cyanide pollution occurs, with probabilities of 0.8 and 1 in Zougnazagmiline and Galgouli, respectively. > 20% of the settled area in the Zougnazagmiline and 5% of that in Galgouli were exposed to cyanide pollution. Logistic regression was able to reliably predict cyanide contamination in areas affected by ASGM. The model could be useful for decision-makers to plan ASGM-site decontamination.

International audience

Soil and water samples were collected from a watershed in Burkina Faso where illegal artisanal gold extraction using cyanidation occurs. The samples were used to evaluate cyanide contamination and the presence of cyanide degrading bacteria (CDB). Free cyanide (F-CN) was detected in all samples, with concentrations varying from 0.023 to 0.9 mg kg(-1), and 0.7-23 μg L(-1) in the soil and water samples, respectively. Potential CDB also were present in the samples. To test the effective F-CN degradation capacity of the isolated CDB species, the species were cultivated in growth media containing 40, 60 or 80 mg F-CN L(-1), with or without nutrients, at pH 9.5 and at room temperature. More than 95% of F-CN was degraded within 25 h, and F-CN degradation was associated with bacterial growth and ammonium production. However, initial concentrations of F-CN higher than 100 mg L(-1) inhibited bacterial growth and cyanide degradation. Abiotic tests showed that less than 3% of F-CN was removed by volatilization. Thus, the degradation of F-CN occurred predominately by biological mechanisms, and such mechanisms are recommended for remediation of contaminated soil and water. The bacteria consortium used in the experiment described above exist in a Sahelian climate, which is characterized by a long hot and dry season. Because the bacteria are already adapted to the local climate conditions and show the potential for cyanide biodegradation, further applicability to other contaminated areas in West Africa, where illegal gold cyanidation is widespread, should be explored.

Since 2007, the primary collection of domestic wastes from households to the transfer stations was removed from the waste management system in Abidjan, capital city of Cote d'Ivoire. The situation has led to the emergence of “private” waste pre-collectors (WPC) to compensate the gap and to respond to urban population needs in terms of public health. The objective of the study was to understand the motivation, role and importance of these WPC in the management of the municipal wastes. Through a survey of 400 households, 37 WPC and staff of institutions involved in the municipal wastes management, it was shown that there is no legal framework governing the activity and that the large majority of the WPC are informal workers using only very basic equipment such as wheelbarrows and carts. Most of them are between 20 and 39 years old and have joined the sector because of unemployment. They have mean monthly revenue of about 70,000 FCFA (115 USD), which is slightly higher than the minimum salary of 60,000 FCFA. Besides, 78% of the population using the service are highly satisfied. Moreover, people in charge of sanitation and hygiene in the different municipalities of Abidjan have confirmed the benefits from the WPC works. They have not only contributed to the extension of the areas covered by the overall waste management system but also greatly contributed to the improvement of Abidjan's population living environment by minimizing the environmental risks associated with the accumulation of wastes on streets. It was accepted by the stakeholders that the WPC should continue managing the pre-collection line. However, for the sustainability of the service, it was strongly advised that the WPC move into formal structures with the support from the government and non-governmental organizations.

This study aimed to investigate and understand the zero-level detection of Escherichia coli (E. coli) at the outlet of an improved waste stabilization pond. Wastewaters were collected from the International Institute for Water and Environmental Engineering (2iE) campus and were subjected to biological treatment. The system included two-stage Anaerobic Reactors followed by a Baffled Pond (AR-BP) with recycled plastic media as a medium for attached growth and a control pond (CP). Three vertical baffles were installed, giving four compartments in the baffled pond (BP). The research was conducted on the pilot scale from March to July 2014, by monitoring E. coli, pH, temperature, dissolved oxygen (DO) and chlorophyll-a in each compartment and at different depths. The results show that E. coli concentrations were lower in top layers of all compartments with an undetectable level in the last compartment up to 0.60 m deep. E. coli mean removal efficiencies and decay rates were achieved by significant difference in BP (4.5 log-units, 9.1 day(-1)) and CP (1.1 log-units, 1.1 day(-1)). Higher values of pH (≥9), temperature (≥32°C), DO (≥ 8 mg/L) and chlorophyll-a (≥ 1000 µg/L) were observed at the surface of BP, whereas lower values were shown at the bottom. Sedimentation combined with the synergetic effects of the physicochemical parameters and environmental factors would be responsible for the inactivation of E. coli in BP. It was concluded that the AR-BP could be applied as an alternative low-cost wastewater treatment technology for developing countries and recommended for reuse of their effluent for restricted peri-urban irrigation.

The social status improvement and the degree of integration of the informal recycling sector, by using InteRa, made by the AKAMASOA association interventions at the Andralanitra dumpsite (Antananarivo, Madagascar) was assessed. 20% of the workers from the three activities at the site were interviewed: 325 scavengers, 12 compost producers and three soap manufacturers. It was found that the incomes of Andralanitra workers are relatively low compared to that of people working in the same field in other countries (30–60 USD/month). However, with the social support from AKAMASOA, their living conditions were greatly improved, allowing them to own their house, have access to water and sanitation facilities and send their children to school or subscribe to health insurance and bank savings. Though they do not experience the common socio-economic issues faced by informal workers at dumpsites and their works are highly appreciated by the solid waste management (SWM) stakeholders, there is no official planned intervention to formalise their situation. Thus, InteRa has shown low scores in SWM and organisational interfaces and high scores in materials/value chain and social interfaces. AKAMASOA actions are good examples of successful NGO interventions to improve the dumpsites’ informal recycling social status. The findings suggest that full integration into the SWM system should be supported by municipalities through the setting of policy and regulations on the access to dumpsites and the exploitation of the wastes.

The treatment of greywater collected from an urban slum area of Ouagadougou, Burkina Faso, by vermifiltration (VF) was investigated using locally available sawdust as bedding material and Eudrilus eugeniae earthworm. The filtration system was made up of layers of sand, and fine and coarse gravel from the top to the bottom, which was spread inside a cylindrical DN200-PVC pipe. The fine sawdust and density of 6370 worms/m2 were added while the same filtration system without earthworms was used as an experimental control. Batch experiments were conducted at ambient temperature, with hydraulic loading rate of 64 and 191 L m−2 d−1. The raw greywater was highly concentrated with biochemical oxygen demand (BOD5) varying from 690 to 2200 mg/L and pH varying from 4.37 to 7.32. The results showed that Eudrilus eugeniae were able to tolerate temperatures above 40 °C and avoided odour and clogging problems inside the filter. The removal efficiencies of BOD5, chemical oxygen demand, total suspended solid, E. coli and thermotolerant coliforms were better in the vermifilter than in the control system. Moreover, the pH at the exit of the system was close to neutral. Therefore, VF could be applied as an alternative low-cost technology to treat greywater for the urban poor in hot climate areas.

A comparative investigation was conducted for 10 months with sand and fine sawdust vermifilters and a control unit to treat concentrated grey water generated from a poor urban household in Ouagadougou, Burkina Faso. Each of the filters was made up of cylindrical DN200-PVC pipes and filled with 10 cm of gravel at the bottom. On top of the gravel layer, filter 1 (fully sand, F1) was completed with 40 cm of sand and 10 cm of fine sawdust, filter 2 (partially sand, F2) with 20 cm of sand and 30 cm of fine sawdust, respectively, and filter 3 (fully sawdust, F3) and 4 (control, F4) with 50 cm of fine sawdust only. Two hundred Eudrilus eugeniae earthworms were inoculated in each of the vermifilters. The vermifiltration system was supplied with grey water four times per day at a hydraulic loading rate of 64 L/m(2)/day on a batch basis. The removal efficiencies of biological oxygen demand, total chemical oxygen demand, and dissolved chemical oxygen demand (dCOD) by the vermifilters were 25-30% higher than the control, but little differences were observed in terms of total suspended solids and coliform removal efficiencies. Though there was no significant difference in the performance of the three vermifilters (p 0.05), except for dCOD removal efficiency, the lifespan of F2 and F3 was longer than that of F1. Therefore, fine sawdust can substitute sand as a filter medium in vermifilters.

The behaviour of As(III), As(V), MMAv and DMAv in batch activated sludge process were investigated. Experiments were carried out by using aerobic and anoxic reactors with an initial As concentration of 100 μg l−1. Under aerobic condition, As(III) was oxidized to As(V) within 9 hours, some part of MMAv was methylated to DMAv and some other part was demethylated to As(III), which in turn was immediately oxidized to As(V). Under anoxic condition, As(V) was reduced to As(III) within the same time-course. No significant transformation occurred during experiments conducted with DMAv. It was found that all reactions were biologically mediated. The overall As removal was low (