Suchergebnisse

[Abstract] The treatment of the industrials off-gas strongly evolves with change of the environmental legislation on a worldwide scale. Biotechnics existing for their treatment sometimes present limits for some volatile organic compounds (VOC) such as BTEX because of their poor water solubility. The use of two phase-partitioning bioreactors (TPPB) is an interesting alternative in this case. In this work, a laboratory scale TPPB (water / silicone oil) was monitored at high level of Isopropropylbenzene (IPB) air pollution (7g/Nm3) and a flow of 1 VVM. We focused ourselves on the inoculation with the strain Rhodococcus erythropolis T 902.1. We showed that the increase of the inoculums size to 5 g DM/l. induces a better initial abatement of the pollutant, however performances of the TPPB decrease quickly because of cellular mortality. The use of a smaller inoculum (0,2g DM /l) seems to be a good compromise to observe progressive improvement of the IPB abatement with adaptation of biomass. The TPPB was followed during 38 days in order to confirm its potentialities and characterise its evolution. We showed that the performances of the TPPB are maintained with an elimination rate near to 63 % for IPB polluted air (7 g/Nm3) and punctually reach 92 %. The biomass grows gradually and stabilizes itself around 10 g/l. With fluorescent double stain Rhodamine/ propidium iode, we also shown that cellular viability strongly evolve: cellular viability was low (30 %) in the first operating hours but is quickly increased after adaptation to IPB (80%); we also suggested an endorespiration phenomenon in the bioreactor. In this work, we could confirm the previously estimated elimination performances of the two- phase partitioning bioreactor with silicone-oil as second phase. Elimination rate of a monoaromatic compound at high concentration (7 g / Nm3) can be maintained between 240 g /m3.h and 360 g /m3.h. in the TPPB.

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. ; Peer reviewed

Phytosanitary crop protection products have shown their impact on the environment. They may not be very selective and their excessive use in agriculture causes pollution of soil and groundwater, destruction of many beneficial insects and the emergence of resistant pests. Hence there is strong public and political pressure driven by consumers to implement phytosanitary alternatives that are less aggressive to the environment, such of biopesticides. Biopesticides and, in particular, mycopesticides are frequently used as an environmentally friendly tools to reduce plant diseases by inhibiting the growth of pathogens and inducing resistance in plants. In this review, we will first analyze the current evolution of the global market of biopesticides. Boosted by different political initiatives all over the world, this market has increased 6-fold between 2005 and 2016. In 2016, it represented 6% of the global pesticide market with a compound annual growth rate (CGAR) of 14.1%. The mycopesticides accounted for only 10% of the global biopesticide market of 2016. We then focused on two main factors which should contribute to the future development of mycopesticides: the large panel of their modes of action and the physiological state of the active product. Indeed, several modes of action could, in some instances, increase the efficacy of a biopesticide and postpone the emergence of resistance mechanism. The broad set of mechanisms use by Trichoderma harzianum and T. atroviride to reduce plant diseases: nutrient competition, direct antagonism, mycoparasitism and induction of resistance mechanism in plants were developed as an example. Stability of the active substance is another essential factor for creating competitive mycopesticides. For this, the choice of propagule types could be a major factor in enhancing their stability. This choice was discussed highlighting the advantages of conidia or sporidia from solid-state fermentation. To end with, the registration process in European Union was described revealing another limiting factor that delays the development of mycopesticides in this zone. ; Peer reviewed

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. This methane yield corresponded to 7% of calorific power of wood. 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. Therefore, methane production from the sole MI leaves seems unfavorable by comparison to MU leaves at the ambient temperature in tropical regions. Their solid and liquid residues obtained after anaerobic digestion would be efficient fertilizers. However, the methane productivity of both leaves could be improved by anaerobic co-digestion. ; Peer reviewed