Caractérisation des paramètres physico-chimiques et microbiologiques au cours d’un cycle de compostage d’ordures ménagères

Composting is a self-heating, aerobic, biodegradative process of organic waste materials. The present study investigates the prevailing of both physico-chemical conditions such as temperature, total organic matter, moisture, C/N ratio, pH and microbial parameters such as faecal indicator bacteria, Pseudomonas as pathogenic bacteria, mesophilic and thermophilic bacteria, microbial biomass present in a compost of municipal solid waste. So, our results showed the effect of temperature on microbial diversity. In fact, when higher temperature are reached, there is a decrease of faecal coliforms, E.coli, and these results dropped respectively from 370 to 40, from 340 to 25 bacteria/g de MS. The mesophilic microorganisms are very active throughout the process until the end where their number decreased. We also remarked the myriad of microoganisms in the compost showed by the evaluation of the total microbial biomass. Microbial biomass C (BC) ranged from 4,86 to 1 g/kg of dry compost from day 5 to day 62, and decreased and reaches 0,44 g/kg in mature compost.BN showed the same trend as BC ranging from 1,472 to 0,443 g/kg of dry compost from day 5 to day 62. This behaviour is probably related with the decreasing availability of readily decomposable substrates with the ongoing of the process. BC and BN showed a strong correlation (r=0,78). Dynamics of BC/BN ratio, index of the chemical composition of the whole microbial population, suggested a shift in the composition of microbial populations during the process from prevailing bacteria and actinomycetes to prevailing fungi. The hygienization of the final product allow its utilization on agriculture as a fertilizer. So, the aim of this work was to follow the different physic-chemical and microbiological parameters dynamics during the composting process of urban solid waste.Le compostage est un procédé aérobie de transformation biologique de matériaux biodégradables pour former, après maturation, un compost stable et riche en humus. La présente étude a permis de montrer les effets des paramètres physicochimiques et microbiologiques sur le déroulement du processus de compostage. L’effet notable des hautes valeurs de la température sur l’élimination des coliformes fécaux, E.coli notamment, permet une hygiénisation du compost avec une diminution respectivement de 370 à 40, de 340 à 25 bactéries/g de MS. On a aussi remarqué que le compost abrite une large diversité microbienne responsable de la biodégradation. La caractérisation microbienne du compostage est importante dans le suivi du processus et dans la détermination de la qualité du produit fini. La biomasse C (BC) varie entre 4,86 et 1 g/kg de compost sec du 5e jour jusqu’au 62e jour, et diminue pour atteindre 0,44 g/kg dans le compost mature. La biomasse N (BN) montre la même évolution que celle de BC et varie de 1,472 à 0,443 g/kg de compost sec du 5e au 62e jour. Cette évolution est vraisemblablement due à une diminution de la biodisponibilité des substrats facilement décomposables. Avec la progression du processus, BC et BN montrent une importante corrélation (r=0,78). L’évolution du rapport BC/BN donne une idée sur la composition chimique de toute la communauté microbienne et suggère une modification dans sa composition au cours du processus allant des bactéries et actinomycètes jusqu’aux champignons. Le produit fini obtenu en fin de cycle de compostage peut être utilisable à des fins agricoles

Biochemical, physiological, and yield responses of lady’s finger (Abelmoschus esculentus L.) grown on varying ratios of municipal solid waste vermicompost

Abstract Purpose In the present study, effect of earthworm-processed MSW was seen on biochemical, physiological, and yield responses of Abelmoschus esculentus L. Methods Plants were grown on different amendment ratios of municipal solid waste vermicompost (MSWVC). Pot experiments were conducted by mixing MSWVC at 0, 20, 40, 60, 80, and 100% ratios to the agricultural soil. Results An increase in photosynthetic rate and stomatal conductance of plants grown at 20 and 40% MSWVC amendment ratios was observed. Total chlorophyll, carotenoid, and protein contents also increased significantly in 20, 40, and 60% amendment ratios at 65 days after germination (DAG). Likewise, proline, peroxidase, and lipid peroxidation increased with increasing levels of MSWVC at both 45 and 65 DAG. Conclusion The study suggests that MSWVC could be used as organic amendment in soil depicted by good yield and antioxidative response of lady’s finger (A. esculentus) at different amendments of MSWVC (up to 60% w/w ratios). Furthermore, agricultural utilization of MSWVC will help in managing dreadful effects of the burgeoning amount of organic solid waste