Assessment of the Potential for Greenhouse Gas Emission Mitigation by the Methanization of Slaughterhouse Waste in the District of Abidjan (Côte d'Ivoire)

Abattoirs are source of huge amounts of waste that contribute to global greenhouse gas (GHG) emissions and thus, to the global warming and climate change. Treating these was with biodigester technology could be a suitable alternative to GHG emission mitigation. The objective of this study is to evaluate the potential for GHG emission mitigation by a biodigester to be installed at the abattoir of Port-Bouët in the District of Abidjan as a pilot project. More specifically, it aims to: (i) estimate the daily biogas production from 2013 to 2018 according to the mathematical methods of Hashimoto, Gwogon, and Amahrouch, and an empirical method, (ii) evaluate the environmental benefits of the biodigester by estimating the avoided GHG emissions according to the methods mentioned above.The mathematical methods used are those of Hashimoto, Gwogon and Amahrouch. In addition, the empirical method was also used. The results showed that regardless of the method, the amount of biogas increased from 2013 to 2017 and decreased in 2018. The highest daily biogas productions are obtained in 2017 for all methods. Thus, the biogas volumes are 564.50 m3 in a biodigester of 2792.64 m3 according to the Hashimoto method, 724.15 m3 for the biodigester of 2228.14 m3 with the Gwogon method and 557.03 m3 for digesters of volumes 2785.17 m3 calculated with the Amahrouch method. According to the empirical method, the maximum volume of biogas is 631.31 m3. Regarding the amount of CO2 avoided per kilogram of dung, the values ranged from 41579.88 to 71561.17 kg CO2e for the Gwogon method, 41643.46 to 71670.58 kg CO2e for the empirical method, 41689.19 to 71749.30 kg CO2e for the Hashimoto method, and 41694.30 to 71758.10 kg CO2e for the Amahrouch method. These results show a great environmental and economic potential of the installation of a biodigester for the treatment of the waste of the slaughterhouse of Port-Bouët. The choice of the anaerobic digestion process was a continuous mixed biodigester where the substrate is introduced daily with liquid

Assessment of the Potential for Greenhouse Gas Emission Mitigation by the Methanization of Slaughterhouse Waste in the District of Abidjan (Côte d'Ivoire)

Abattoirs are a source of huge waste that contributes to global greenhouse gas (GHG) emissions and, thus, to global warming and climate change. This study aimed to evaluate the GHG emission mitigation potential of a biodigester to be installed at the abattoir of Port-Bouët in the District of Abidjan. Mathematical methods developed by Hashimoto, Gwogon, and Amahrouch and an empirical method were used to assess this mitigation potential. The results showed that regardless of the methods, biogas volumes increased from 2013 to 2017 and decreased in 2018. The highest daily biogas production was obtained in 2017 for all the methods. According to Hashimoto's method, the biogas volume was 564.50 m3 in a biodigester of 2792.64 m3. Gwogon's method led to a biogas volume of 724.15 m3 for a 2228.14 m3 biodigester. The calculated volume of biogas with the Amahrouch method was 557.03 m3 for a 2785.17 m3 biodigester. The empirical method showed a maximum biogas volume of 631.31 m3. The amount of CO2 avoided per kilogram of dung ranged from 41579.88 to 71561.17 kg CO2e, 41643.46 to 71670.58 kg CO2e, 41689.19 to 71749.30 kg CO2e for Gwogon, empirical and Hashimoto methods, respectively. The values ranged from 41694.30 to 71758.10 kg CO2e for the Amahrouch method. These results show a biodigester's tremendous environmental and economic potential for treating the waste of the slaughterhouse of Port-Bouët

Valorisation Energetique des Dechets Agricoles : cas de la Pomme de Cajou dans le Departement de Tanda (Côte d’Ivoire)

Cette étude s’est proposée de valoriser la pomme de cajou e combustible. Le matériel est constitué de pommes de cajou séchée non carbonisée (PCSNC), pommes de cajou fermentées séchées carbonisées (PCFSC),, pommes de cajou séchées et carbonisées (PCSC), briquettes comportant 100% de pommes carbonisées et 0% de sciure de bois carbonisée (BPC100), briquettes comportant 80% de pommes carbonisées et 20% de sciure de bois carbonisée (BPC80), briquettes comportant 70% de pommes carbonisées et 30% de sciure de bois carbonisée (BPC70), briquettes comportant 60% de pommes carbonisées et 40% de sciure de bois carbonisée (BPC60). Ces combustibles ont été caractérisés en déterminant la quantité de chaleur dégagée, la durée de combustion, le temps d’ébullition, le niveau de dégagement de fumée, la masse de suie après combustion et le taux de cendres. Les valeurs obtenues pour ces paramètres ont été comparées à celles du charbon de bois. Il ressort que les quantités de chaleur dégagées par PCFNC (963 KJ) et PCSNC (943 kJ) sont relativement proches de celle (1122 kJ) du charbon de bois. Pour la durée de combustion, ce sont les briquettes et le charbon de bois témoin qui mettent plus de temps à se consumer (60 minutes, environ). Le temps le plus court d’ébullition de l’eau est obtenu avec BPC100 (10,98 minutes contre 15,45 minutes pour le charbon de bois). Les combustibles à base de pommes de cajou ont tous dégagé de la fumée et ont favorisé un dépôt de suie après la combustion contrairement au charbon de bois. Au niveau de la cendre, BPC60 et BPC70 ont produit moins de cendre (10g) que le charbon de bois (12,5g). Au vu de ces résultats, si certaines caractéristiques de la pomme de cajou sont améliorées, sa valorisation énergétique est possible. This study intended to valorize the cashew apple or cashew nut into fuel. The material consists of cashew apples and sawdust, which allowed us to obtain 8 types of fuel. This includes dried cashew apples without carbonization (PCSNC), dried fermented cashew apples with carbonization (PCFSC), dried cashew apples with carbonization (PCSC), and briquettes with 100% carbonized apples and 0% sawdust with carbonization (BPC100), briquettes with 80% carbonized apples and 20% carbonized sawdust (BPC80), briquettes with 70% carbonized apples and 30% carbonized sawdust (BPC70), briquettes with 60% carbonized apples and 40% carbonized sawdust (BPC60). These fuels were characterized by determining the amount of released heat, combustion time, boiling time, level of smoke release, soot mass after combustion, and ash content. The values obtained for these parameters were compared with those of charcoal. The heat release of PCFNC (963 kJ) and PCSNC (943 kJ) is relatively close to that of charcoal (1122 kJ). The briquettes and the control charcoal take longer to burn (about 60 minutes, in terms of burning time. The shortest water boiling time was obtained with BPC100 (10.98 minutes versus 15.45 minutes for charcoal). Cashew apple fuels all gave off smoke and promoted soot deposition after combustion. This was not the same as charcoal’s case. Regarding ash generation, BPC60 and BPC70 produced less ash (10g) than charcoal (12.5g). Considering these results, if some characteristics of the cashew apple are improved, its energy valorization is possible

Fenton-like oxidation and mineralization of phenol using synthetic Fe(II)-Fe(III) green rusts

International audienceBackground, aim, and scope In literature, the environmental applications of green rust (GR) have mainly been pointed out through the reduction of inorganic contaminants and the reductive dechlorination of chlorinated organics. However, reactions involving GR for the oxidation and mineralization of organic pollutants remain very scantly described. In this study, the ability of three synthetic Fe(II)-Fe(III) green rusts, GR(CO 3 2− ), GR(SO 4 2− ), and GR(Cl−), to promote Fenton-like reaction was examined by employing phenol as a model pollutant. Unlike the traditional Fenton's reagent (dissolved Fe(II) + H2O2), where the pH values have to be lowered to less than 4, the proposed reaction can effectively oxidize the organic molecules at neutral pH and could avoid the initial acidification which may be costly and destructive for the in situ remediation of contaminated groundwater and soils. The green rust reactivity towards the oxidative transformation of phenol was thoroughly evaluated by performing a large kinetic study, chemical analyses, and spectroscopic investigations. Materials and methods The kinetics of phenol removal was studied at three initial phenol concentrations for three green rusts under similar conditions (pH = 7.1; 1 g L−1 of GR; 30 mM H2O2) and reaction rates were calculated based on mass and surface area. The oxidation rate constants are compared with that of magnetite, a well-known mixed iron (II, III) oxide. The mineralization of phenol was investigated at various H2O2 doses and GR concentrations. In order to describe the phenol transformation in GR/H2O2 system, several investigations were performed including HPLC and ion exclusion chromatography analysis, TOC, dissolved iron, and H2O2 concentration measurements. Finally, X-ray powder diffraction and Raman spectroscopy were used to identify the oxidation products of GRs. Results and discussion In GR/H2O2 system, the kinetics of phenol removal at neutral pH was very fast and independent of the initial phenol concentration. No aromatic intermediates were detected and final by-products are mainly of short chain organic acids (oxalic acid and formic acid). Green rusts exhibit different reactivity toward Fenton-like oxidation of phenol. Both on mass and surface area basis, the reactivity of Fe(II)-Fe(III) species toward the oxidation of phenol was highest for GR(Cl−), little less for GR(SO 4 2− ) or GR(CO 3 2− ), and even less for magnetite (Fe3O4). Phenol degradation pseudo-first order rate constants (k surf) values were found to be: 13 × 10−4, 3.3 × 10−4, 3.5 × 10−4, and 0.4 × 10−4 L m−2 s−1 for GR(Cl−), GR(SO 4 2− ), GR(CO 3 2− ), and Fe3O4, respectively. The mineralization yield of phenol as well as the decomposition rate of H2O2 was higher for GR(Cl−) than for GR(SO 4 2− ) or GR(CO 3 2− ), mainly due to the higher Fe(II) content of GR(Cl−). Both X-ray diffraction analysis and Raman spectroscopy showed that the oxidation of GR with H2O2 may lead to feroxyhyte (δ-FeOOH), with possible formation of poorly crystallized goethite (α-FeOOH), depending on GR type. Conclusions This original work shows that the heterogeneous Fenton-like reaction using GR/H2O2 is very effective toward degradation and mineralization of pollutants. In summary, this study has demonstrated that the green rust-promoted oxidation reaction could contribute to the transformation of water contaminants in the presence of H2O2. Recommendations and perspectives These results could serve as the basis for the understanding of the transformation of organic pollutants in iron-rich soils in the presence of chemical oxidant (H2O2) or for the development of wastewater treatment process. However, some experimental parameters should be optimized for a high-scale application. Further work needs to be done for the reactive transport and transformation of organic compounds in a green rust-packed column. The reusability of GR in mineral-catalyzed reaction should be also investigated

Étude expérimentale du couplage entre croissance bactérienne et transport d'un polluant organique en milieu poreux

Un dispositif expérimental a été développé pour l'étude du couplage de la croissance d'un biofilm de Shewanella oneidensis MR-1 et du transport conservatif de l'Erioglaucine. La croissance du biofilm a été suivie par mesure de conductivité hydraulique et par acquisition d'images à l'aide d'une caméra digitale. La fraction volumique du biofilm a été caractérisée par des essais d'élution d'une macromolécule (i.e. : le Bleu Dextran) par analogie avec les méthodes de chromatographie d'exclusion ou de filtration sur gel. Ainsi au bout de 29 jours, un biofilm quasi-homogène sur l'ensemble de la cellule d'écoulement (0,1.0,1.0,05m3) et équivalent à 50% du volume poral a été formé. L'influence de la croissance du biofilm sur les propriétés de transport du milieu a été évaluée. Les essais de transport conservatif de l'Erioglaucine effectués pour deux vitesses d'injection et à deux stades de croissance du biofilm (17 et 29 jours) ont montré l'influence d'hétérogénéités locales sur les paramètres de transport (i.e. : la porosité, la perméabilité et la dispersion hydrodynamique). Ainsi après 17 jours de culture quand le biofilm occupe partiellement le milieu poreux (moitié inférieure) un modèle à deux équations ou double milieu permet de caractériser le transport conservatif. A contrario après 29 jours de culture où le biofilm occupe tout le milieu poreux, un comportement fickien classique caractérise le transport. Les valeurs théoriques du coefficient de dispersion longitudinale prédites par la méthode de prise de moyenne volumique ont permis de reproduire de manière satisfaisante le comportement observé expérimentalementAn experimental device was performed for the study of coupling the growth of a Shewanella oneidensis MR-1 bacterial biofilm and the non reactive transport of Brilliant Blue FCF. The biofilm growth was monitored by hydraulic conductivity measurements and by image acquisition with a digital camera. The biofilm volume fraction was estimated through tracer experiments with a macromolecular tracer (i.e., Dextran Blue) as in size-exclusion chromatography or gel filtration chromatography. Then after 29 days of bacterial culture a quasi-homogenous biofilm was grown in the whole flow cell (0,1.0,1.0,05m3) occupying about 50% of void space volume. The influence of biofilm growth on porous media transport properties was evaluated. Conservative tracer experiments with Brilliant Blue FCF run at two hydrodynamic conditions and at two growth steps of biofilm (17 and 29 days) showed the influence of local heterogeneities on transport parameters (i.e., porosity, permeability and hydrodynamic dispersion). Then at 17 days of growth when the biofilm partially covers the porous medium (bottom half of the flow cell) a two-equation model or double-layer model was suitable to characterize the conservative transport. A contrario after 29 days of growth, when the biofilm covers the whole porous medium, a classical fickian model was convenient. Numerical values of longitudinal dispersion coefficient from volume averaging well fitted experimental resultsMETZ-SCD (574632105) / SudocNANCY1-Bib. numérique (543959902) / SudocNANCY2-Bibliotheque electronique (543959901) / SudocNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Assessment of the Potential for Greenhouse Gas Emission Mitigation by the Methanization of Slaughterhouse Waste in the District of Abidjan (Côte d'Ivoire)

Abattoirs are source of huge amounts of waste that contribute to global greenhouse gas (GHG) emissions and thus, to the global warming and climate change. Treating these was with biodigester technology could be a suitable alternative to GHG emission mitigation. The objective of this study is to evaluate the potential for GHG emission mitigation by a biodigester to be installed at the abattoir of Port-Bouët in the District of Abidjan as a pilot project. More specifically, it aims to: (i) estimate the daily biogas production from 2013 to 2018 according to the mathematical methods of Hashimoto, Gwogon, and Amahrouch, and an empirical method, (ii) evaluate the environmental benefits of the biodigester by estimating the avoided GHG emissions according to the methods mentioned above.The mathematical methods used are those of Hashimoto, Gwogon and Amahrouch. In addition, the empirical method was also used. The results showed that regardless of the method, the amount of biogas increased from 2013 to 2017 and decreased in 2018. The highest daily biogas productions are obtained in 2017 for all methods. Thus, the biogas volumes are 564.50 m3 in a biodigester of 2792.64 m3 according to the Hashimoto method, 724.15 m3 for the biodigester of 2228.14 m3 with the Gwogon method and 557.03 m3 for digesters of volumes 2785.17 m3 calculated with the Amahrouch method. According to the empirical method, the maximum volume of biogas is 631.31 m3. Regarding the amount of CO2 avoided per kilogram of dung, the values ranged from 41579.88 to 71561.17 kg CO2e for the Gwogon method, 41643.46 to 71670.58 kg CO2e for the empirical method, 41689.19 to 71749.30 kg CO2e for the Hashimoto method, and 41694.30 to 71758.10 kg CO2e for the Amahrouch method. These results show a great environmental and economic potential of the installation of a biodigester for the treatment of the waste of the slaughterhouse of Port-Bouët. The choice of the anaerobic digestion process was a continuous mixed biodigester where the substrate is introduced daily with liquid

Spatial modeling of nitrate transfer in an agricultural watershed: The Ono watershed case (Côte d’Ivoire)

Le Bassin Versant de Ono (BVO), dans la région du Sud Comoé, est dominé par les cultures agro-industrielles utilisant des fertilisants chimiques. Cela constitue une source importante de pollution, particulièrement aux nitrates. Cette étude visait à modéliser le transfert des nitrates vers les eaux de surface du BVO en deux étapes: (i) modéliser l’érosion hydrique de la zone et (ii) estimer la quantité d’azote dans le BVO. La combinaison de ces paramètres de vulnérabilité, précédée d’une analyse multicritère, a permis d’obtenir une carte des risques de transfert des nitrates vers les eaux de surfaces. Cette cartographie révèle que les classes de Risques Faible et Très Faible représentent 65,5% du BVO. Les classes de Risque Elevé représentent 25,2% de la superficie du BVO et concernent la zone de production d’ananas de Ono-Salci près de la lagune Ono. Les classes de Risque Moyen occupent 9,29% du bassin et concernent les zones de production d’hévéa et de palmier à huile de Bongo. Ainsi, cette analyse multicritère spatiale simple a permis de simuler les risques de transfert des nitrates vers les eaux de surface du BVO. Cette étude être pourrait approfondie en analysant les nitrates dans des échantillons d’eau de surface du BVO. Mots clés: Nitrates, Pollution diffuse, Vulnérabilité, Eaux de surface, Agriculture, Culture d’ananas, Bassin versant agricoleThe Ono Watershed (OWB), in the South Comoé region, is dominated by agro-industrial crops using chemical fertilizers. This constitutes a major source of nitrate pollution. This study aimed to model the transfer of nitrates to the surface waters of the BVO in two steps: (i) modeling the water erosion of the area and (ii) estimating the amount of nitrogen in the BVO. The combination of these vulnerability parameters, preceded by a multi-criteria analysis, resulted in a map of the risk of nitrate transfer to surface waters. This map reveals that the Low and Very Low-Risk classes represent 65.5% of the BVO. The High-Risk classes represent 25.2% of the BVO and concern the pineapple production area of Ono-Salci near the Ono Lagoon. The Medium Risk classes occupy 9.29% of the basin and concern Bongo's rubber and oil palm production areas. Thus, this simple spatial multi-criteria analysis allowed for the simulation of the risk of nitrate transfer to surface waters in the BVO. This study could be extended by analyzing nitrates in surface water samples from the BVO. Key words: Nitrates, Diffuse pollution, Vulnerability, Surface water, Agriculture, Pineapple crop, Agricultural watershe

Optimal mode for delivery of seasonal malaria chemoprevention in Ouelessebougou, Mali: A cluster randomized trial

International audienceBACKGROUND:Seasonal malaria chemoprevention (SMC), the administration of complete therapeutic courses of antimalarials to children aged 3-59 months during the malaria transmission season, is a new strategy recommended by the World Health Organization (WHO) for malaria control in Sahelian countries such as Mali with seasonal transmission. The strategy is a highly cost-effective approach to reduce malaria burden in these areas. Despite the substantial benefits of SMC on malaria infection and disease, the optimal approach to deliver SMC remains to be determined. While fixed-point delivery (FPD) and non-directly observed treatment (NDOT) by community health workers are logistically attractive, these need to be evaluated and compared to other modes of delivery for maximal coverage.METHODS:To determine the optimal mode fixed-point (FPD) vs door-to-door delivery (DDD); directly observed treatment (DOT) vs. non- directly observed treatment (NDOT)), 31 villages in four health sub-districts were randomized to receive three rounds of SMC with Sulfadoxine-pyrimethamine plus Amodiaquine (SP+AQ) at monthly intervals using one of the following methods: FPD+DOT; FPD+NDOT; DDD+DOT; DDD+NDOT. The primary endpoint was SMC coverage assessed by cross-sectional survey of 2,035 children at the end of intervention period.RESULTS:Coverage defined as the proportion of children who received all three days of SMC treatment during the three monthly rounds based information collected by interview (primary endpoint) was significantly higher in children who received SMC using DDD 74% (95% CI 69% - 80%) compared to FPD 60% (95% CI 50% - 70%); p = 0.009. It was similar in children who received SMC using DOT or NDOT 65%, (95% CI 55% - 76%) versus 68% (95% CI 57% - 79%); p = 0.72.CONCLUSIONS:In summary, door-to-door delivery of SMC provides better coverage than FPD. Directly observed therapy, which requires more time and resources, did not improve coverage with SMC

Measuring the impact of seasonal malaria chemoprevention as part of routine malaria control in Kita, Mali

Abstract Background Seasonal malaria chemoprevention (SMC) is a new strategy recommended by WHO in areas of highly seasonal transmission in March 2012. Although randomized controlled trials (RCTs) have shown SMC to be highly effective, evidence and experience from routine implementation of SMC are limited. Methods A non-randomized pragmatic trial with pre-post design was used, with one intervention district (Kita), where four rounds of SMC with sulfadoxine + amodiaquine (SP + AQ) took place in August–November 2014, and one comparison district (Bafoulabe). The primary aims were to evaluate SMC coverage and reductions in prevalence of malaria and anaemia when SMC is delivered through routine programmes using existing community health workers. Children aged 3–59 months from 15 selected localities per district, sampled with probability proportional to size, were surveyed and blood samples collected for malaria blood smears, haemoglobin (Hb) measurement, and molecular markers of drug resistance in two cross-sectional surveys, one before SMC (July 2014) and one after SMC (December 2014). Difference-in-differences regression models were used to assess and compare changes in malaria and anaemia in the intervention and comparison districts. Adherence and tolerability of SMC were assessed by cross-sectional surveys 4–7 days after each SMC round. Coverage of SMC was assessed in the post-SMC survey. Results During round 1, 84% of targeted children received at least the first SMC dose, but coverage declined to 67% by round 4. Across the four treatment rounds, 54% of children received four complete SMC courses. Prevalence of parasitaemia was similar in intervention and comparison districts prior to SMC (23.4 vs 29.5%, p = 0.34) as was the prevalence of malaria illness (2.4 vs 1.9%, p = 0.75). After SMC, parasitaemia prevalence fell to 18% in the intervention district and increased to 46% in the comparison district [difference-in-differences (DD) OR = 0.35; 95% CI 0.20–0.60]. Prevalence of malaria illness fell to a greater degree in the intervention district versus the comparison district (DD OR = 0.20; 95% CI 0.04–0.94) and the same for moderate anaemia (Hb < 8 g/dL) (DD OR = 0.26, 95% CI 0.11–0.65). The frequency of the quintuple mutation (dhfr N51I, C59R and S108N + dhps A437G and K540E) remained low (5%) before and after intervention in both districts. Conclusions Routine implementation of SMC in Mali substantially reduced malaria and anaemia, with reductions of similar magnitude to those seen in previous RCTs. Improving coverage could further strengthen SMC impact. Trial registration clinical trial registration number NCT0289429

Flow diagram.

<p>Flow diagram.</p