Study of anaerobic biodegradation of Mangifera indica (mango) and Manihot utilissima (cassava) leaves

The population growth of these last two decades leaded to an increase of waste in the City Province of Kinshasa (VPK), capital of the Democratic Republic of Congo. Deprived by an effective management system, the VPK produces essentially vegetal wastes that are constituted for the greater part of dead leaves. These wastes bother and pollute the environment. On another point of view, the Kinshasa households meet enormous difficulties for soil fertilization and to collect wood for energy. Its overexploitation of the wood entails the deterioration of the ecosystems and the public health. Therefore in order to contribute to the reduction of all these difficulties simultaneously, the aim of this thesis was to investigate the methanization of these wastes since this technique is relatively simple, fast and non expensive. So, the methanation was performed at 30°C on the leaves of Mangifera indica (MU, mango) and of Manihot utilissima (MI, cassava) that are the most accessible of the VPK. The biochemical methane potentials of the MU and MI leaves demonstrated that the MU leaves were favorable to the methanation due to their low content in bioactive substance (secondary metabolites) and their low C/N ratio. In addition, their digestates would be an effective fertilizing. By contrast, the MI leaves were unfavorable to the methanation since the methanogenesis was inhibited, probably because of their composition rich in carbon and secondary metabolites (lignine, polyphenols, saponines and anthraquinones). However, these metabolites would be beneficial for the methanation in lower contents than 0.3 g/l in the culture medium. The anaerobic co-digestion improved the daily methane yields of these two leaves. The biogas produced with this process would represent about 28 % of the wooden annual domestic consumption and its digestate would cover annually the all agricultural and forest degraded areas. So, the domestic methanation or on site or near the site of waste generation would be favored to avoid the cost of their transport and their industrial treatment. A promising pilot essay has been achieved

Optimization of the methane production from Mangifera Indica (mango) and Manihot Utilissima (cassava) leaves in co-digestion

Leaves of Mangifera indica (MI, mango leaves) and Manihot utilissima (MU, cassava leaves) are available in tropical regions and are the most accessible vegetable waste of Kinshasa Province, capital of the Democratic Republic of Congo. The main objective of this study was to investigate the optimization of methane production from MI and MU leaves in co-digestion by BMP tests at 30°C. The yields for 100 days achieved from the anaerobic digestion of up to 61.3 g raw matters in 1 l medium were 0.001 l/g and 0.100 l CH4/g volatile solids of MI and MU leaves respectively. By comparison to MI, MU leaves are generally characterized by a higher in mineral content. The TOC and TKN related to MU were slightly lower and 6-fold higher respectively than the corresponding levels in MI. Therefore, the carbon to nitrogen ratio C/N, i.e. about 7, was significantly different regarding the range from 20 to 30 commonly recommended for optimal anaerobic digestion. The reason why, MU and MI leaves were mixed for correcting their C/N ratios. Therefore, leaves yields of methane production in relation to volatile solids were improved. The MU and MI yields in the mixture of MU (75%) and MI (25%) have increased; they were 0.121 l/g and 0.114 l CH4/g volatile solids respectively or nearly 1-fold higher and nearly 100-fold higher respectively than the corresponding leaves in the isolated digestion

Impact of different plant secondary metabolites addition: saponin, tannic acid, salicin and aloin on glucose anaerobic co-digestion

peer reviewedVegetal waste and some wastewater of agro-food industries contain plant secondary metabolites (PSMs). It was showed in nutritional researches that these substances such as saponins and tannins reduced the methane production in the rumen. To our knowledge no study was done in the waste treatment domain to evaluate the inhibitory effect of the principal glycosidic metabolites from the wastewater or vegetal waste on their own methane-producing anaerobic digestion. Therefore in this paper BMP tests were carried out at 30°C with four commercial PSMs (CPSMs) in mixture with glucose monohydrate (Gl) used as control sample. These CPSMs were saponin from Quilaja Saponaria Molina Pract (Sap), tannic acid (Tan), salicin (Sal) and aloin from Curacao Aloe (Alo) representing respectively saponins, tannins, alcoholic glycosides and anthraquinones sources. Acidogenesis and acetogenesis were recorded for all the mixtures of Gl and CPSMs; however their conversion rates decreased with the increase of the concentrations of CPSMs. By contrast, the methanogenesis was inhibited at concentrations of CPSMs above 0.3 g/l. The inhibition degree for aromatic compounds on the anaerobic biodegradation of Gl seemed directly to depend on the numbers of benzene rings in the medium and the synergism. Thus, the highest inhibition of the biogas production from Gl was recorded for Alo, followed by Sap, Tan and Sal. However, the highest inhibition of the methane production from Gl was recorded with Sap, Alo, Tan and Sal. It was supposed that the toxicity potentials of these PSMs on the own biomethanization would be in following decreasing order: Sap or Alo, Tan and Sal. Therefore, the concentration of PSMs alone or in mixture in a digester should be bellow 0.3 g/l. for a better methanization .Thèse : Etude de la biodégradation anaérobie des feuilles de Mangifera Indica (manguier) et Manihot Utilissima (manioc

Potential disposal of green waste (Mangifera indica and Manihot utilissima leaves) by anaerobic digestion in Kinshasa (DRC)

info:eu-repo/semantics/publishe

Potentiel d’élimination des déchets végétaux (feuilles de Mangifera Indica et de Manihot Utilissima) par méthanisation à Kinshasa (République Démocratique du Congo)

La République Démocratique du Congo produit annuellement environ 2,2 millions de tonnes de déchets dans sa capitale, Kinshasa. Ces déchets sont constitués de 66 % de matières organiques dans lesquelles 94 % sont des déchets végétaux et la majorité des feuilles mortes. Parmi ces feuilles, celles de Mangifera Indica et Manihot Utilissima sont les plus accessibles. Elles sont générées via les ménages et les marchés, mais ne sont pas recyclées convenablement. Certains maraîchers les utilisent irrationnellement comme engrais et n’obtiennent pas les résultats attendus. À cet effet, ces déchets gênent et polluent l’environnement. D’autre part, les ménages kinois éprouvent d’énormes difficultés pour s’approvisionner en énergie. La surexploitation du bois énergie entraîne la détérioration des écosystèmes et de la santé publique. Ces méfaits seraient réduits simultanément et durablement par l’exploitation rationnelle de la bioénergie et des biofertilisants résultant de la digestion anaérobie ou biométhanisation des déchets végétaux. En supposant que cette biomasse végétale est constituée uniquement des feuilles de Mangifera Indica et de Manihot Utilissima, le pouvoir énergétique du biogaz émanant de leur biométhanisation réduirait respectivement la consommation en bois énergie de 39 % et 134 %. Par ailleurs, la quantité de digestats produits couvrirait par épandage une superficie proche de celle de la déforestation. Ces estimations montrent un potentiel de valorisation de ces déchets végétaux intéressant pour l’assainissement, les besoins énergétiques, l’afforestation et l’agriculture. De ce fait, ils seraient gérés directement dans leurs lieux de génération pour minimiser les coûts de transport et de traitement industriel.In Democratic Republic of Congo, the capital, the city province of Kinshasa produces annually about 2.2 million tons of wastes mainly constituted (66 %) of organic matters containing 94 % are vegetable wastes. Mangifera Indica and Manihot Utilissima leaves are the main components of these wastes. They are generated via the households and the markets but they are not suitably valorized. Some farmers use them like green fertilizer but they do not achieve the expected results. By this fact, these wastes embarrass and pollute the environment with negative consequences on public health. On another point of view, the Kinshasa households meet enormous difficulties to collect enough wood for their energy needs. As a consequence, the anarchical exploitation of wood entails the deterioration of the ecosystems and the public health. These negative impacts on the environment could be reduced sustainably and simultaneously by rational exploitation of bio-energy and bio-fertilizers resulting from the anaerobic digestion or methanization of this vegetable biomass. This energetic potential from methanization of Mangifera Indica and Manihot Utilissima leaves could reduce by 39 % and 134 % the wood consumption in the households respectively. Moreover by land spreading the digestates produced would cover the deforested surface related to the yearly consumption of wood coal. These evaluations show an interesting potential of the vegetable wastes for a cleaner environment, green energy production, reforestation and agriculture. Therefore, these wastes should be sorted out and processed directly in their generation places in order to minimize the costs for transportation and industrial treatment

Potentiel d’élimination des déchets végétaux (feuilles de Mangifera Indica et de Manihot Utilissima) par méthanisation à Kinshasa (République Démocratique du Congo)

La République Démocratique du Congo produit annuellement environ 2,2 millions de tonnes de déchets dans sa capitale, Kinshasa. Ces déchets sont constitués de 66 % de matières organiques dans lesquelles 94 % sont des déchets végétaux et la majorité des feuilles mortes. Parmi ces feuilles, celles de Mangifera Indica et Manihot Utilissima sont les plus accessibles. Elles sont générées via les ménages et les marchés, mais ne sont pas recyclées convenablement. Certains maraîchers les utilisent irrationnellement comme engrais et n’obtiennent pas les résultats attendus. À cet effet, ces déchets gênent et polluent l’environnement. D’autre part, les ménages kinois éprouvent d’énormes difficultés pour s’approvisionner en énergie. La surexploitation du bois énergie entraîne la détérioration des écosystèmes et de la santé publique. Ces méfaits seraient réduits simultanément et durablement par l’exploitation rationnelle de la bioénergie et des biofertilisants résultant de la digestion anaérobie ou biométhanisation des déchets végétaux. En supposant que cette biomasse végétale est constituée uniquement des feuilles de Mangifera Indica et de Manihot Utilissima, le pouvoir énergétique du biogaz émanant de leur biométhanisation réduirait respectivement la consommation en bois énergie de 39 % et 134 %. Par ailleurs, la quantité de digestats produits couvrirait par épandage une superficie proche de celle de la déforestation. Ces estimations montrent un potentiel de valorisation de ces déchets végétaux intéressant pour l’assainissement, les besoins énergétiques, l’afforestation et l’agriculture. De ce fait, ils seraient gérés directement dans leurs lieux de génération pour minimiser les coûts de transport et de traitement industriel.In Democratic Republic of Congo, the capital, the city province of Kinshasa produces annually about 2.2 million tons of wastes mainly constituted (66 %) of organic matters containing 94 % are vegetable wastes. Mangifera Indica and Manihot Utilissima leaves are the main components of these wastes. They are generated via the households and the markets but they are not suitably valorized. Some farmers use them like green fertilizer but they do not achieve the expected results. By this fact, these wastes embarrass and pollute the environment with negative consequences on public health. On another point of view, the Kinshasa households meet enormous difficulties to collect enough wood for their energy needs. As a consequence, the anarchical exploitation of wood entails the deterioration of the ecosystems and the public health. These negative impacts on the environment could be reduced sustainably and simultaneously by rational exploitation of bio-energy and bio-fertilizers resulting from the anaerobic digestion or methanization of this vegetable biomass. This energetic potential from methanization of Mangifera Indica and Manihot Utilissima leaves could reduce by 39 % and 134 % the wood consumption in the households respectively. Moreover by land spreading the digestates produced would cover the deforested surface related to the yearly consumption of wood coal. These evaluations show an interesting potential of the vegetable wastes for a cleaner environment, green energy production, reforestation and agriculture. Therefore, these wastes should be sorted out and processed directly in their generation places in order to minimize the costs for transportation and industrial treatment

Potentiel d’élimination des déchets végétaux (feuilles de Mangifera Indica et de Manihot Utilissima) par méthanisation à Kinshasa (République Démocratique du Congo)

La République Démocratique du Congo produit annuellement environ 2,2 millions de tonnes de déchets dans sa capitale, Kinshasa. Ces déchets sont constitués de 66 % de matières organiques dans lesquelles 94 % sont des déchets végétaux et la majorité des feuilles mortes. Parmi ces feuilles, celles de Mangifera Indica et Manihot Utilissima sont les plus accessibles. Elles sont générées via les ménages et les marchés, mais ne sont pas recyclées convenablement. Certains maraîchers les utilisent irrationnellement comme engrais et n’obtiennent pas les résultats attendus. À cet effet, ces déchets gênent et polluent l’environnement. D’autre part, les ménages kinois éprouvent d’énormes difficultés pour s’approvisionner en énergie. La surexploitation du bois énergie entraîne la détérioration des écosystèmes et de la santé publique. Ces méfaits seraient réduits simultanément et durablement par l’exploitation rationnelle de la bioénergie et des biofertilisants résultant de la digestion anaérobie ou biométhanisation des déchets végétaux. En supposant que cette biomasse végétale est constituée uniquement des feuilles de Mangifera Indica et de Manihot Utilissima, le pouvoir énergétique du biogaz émanant de leur biométhanisation réduirait respectivement la consommation en bois énergie de 39 % et 134 %. Par ailleurs, la quantité de digestats produits couvrirait par épandage une superficie proche de celle de la déforestation. Ces estimations montrent un potentiel de valorisation de ces déchets végétaux intéressant pour l’assainissement, les besoins énergétiques, l’afforestation et l’agriculture. De ce fait, ils seraient gérés directement dans leurs lieux de génération pour minimiser les coûts de transport et de traitement industriel.In Democratic Republic of Congo, the capital, the city province of Kinshasa produces annually about 2.2 million tons of wastes mainly constituted (66 %) of organic matters containing 94 % are vegetable wastes. Mangifera Indica and Manihot Utilissima leaves are the main components of these wastes. They are generated via the households and the markets but they are not suitably valorized. Some farmers use them like green fertilizer but they do not achieve the expected results. By this fact, these wastes embarrass and pollute the environment with negative consequences on public health. On another point of view, the Kinshasa households meet enormous difficulties to collect enough wood for their energy needs. As a consequence, the anarchical exploitation of wood entails the deterioration of the ecosystems and the public health. These negative impacts on the environment could be reduced sustainably and simultaneously by rational exploitation of bio-energy and bio-fertilizers resulting from the anaerobic digestion or methanization of this vegetable biomass. This energetic potential from methanization of Mangifera Indica and Manihot Utilissima leaves could reduce by 39 % and 134 % the wood consumption in the households respectively. Moreover by land spreading the digestates produced would cover the deforested surface related to the yearly consumption of wood coal. These evaluations show an interesting potential of the vegetable wastes for a cleaner environment, green energy production, reforestation and agriculture. Therefore, these wastes should be sorted out and processed directly in their generation places in order to minimize the costs for transportation and industrial treatment

Methane production from the most accessible vegetal wastes of Kinshasa City: mango and cassava leaves

Leaves of Mangifera Indica (MI, mango leaves) and Manihot Utilissima (MU, cassava leaves) are available in tropical regions and are the most accessible vegetal wastes of Kinshasa, capital of Democratic Republic of Congo. These wastes are not suitably managed and are not rationally valorized. They are abandoned in full air, on the soil and in the rivers. They thus pollute environment. By contrast, they can be recuperated and treated in order to produce methane (energy source), organic fertilizer and clean up the environment simultaneously. The main objective of this study was to investigate methane production from MI and MU leaves by BMP tests at 30 °C. The yields achieved from the anaerobic digestion of up to 61.3 g raw matter in 1 l medium were 0.001 l/g and 0.100 l CH4/g volatile solids of MI and MU leaves respectively. The yield of MU leaves was in the range mentioned in the literature for other leaves because of a poor presence of bioactive substrates, and low C/N ratio. By contrast, the methane yield from MI leaves was almost nil suggesting some metabolism inhibition because of their rich composition in carbon and bioactive substrates. Whereas classical acidogenesis and acetogenesis were recorded