The influence of iron concentration on biohydrogen production from organic waste via anaerobic fermentation

Modeling the Methane Production Kinetics of Anaerobic Co-Digestion of Agricultural Wastes Using Sigmoidal Functions

The modified sigmoidal bacteria growth functions (the modified Gompertz, logistic, and Richards) were used to evaluate the methane production process kinetics of agricultural wastes. The mesophilic anaerobic co-digestion experiments were conducted with various agricultural wastes as feedstocks, including cow manure, corn straw, grape leaves, vines, wine residue, strawberry leaves, and tomato leaves. The results showed that anaerobic co-digestion of cow manure and other agricultural wastes increased the methane yields while it prolonged the lag phase time. Compared with the modified Gompertz and logistic models, the modified Richards model obtained higher correlation coefficients and was able to fit experimental data better. The results of this study were expected to determine a suitable model to simulate and study the kinetic process of anaerobic co-digestion with mixed agricultural wastes as feedstocks.

Hydrogen production by dark fermentation from pre-fermented depackaging food wastes

In this study, a specific fraction of food waste, i.e. depackaging waste, was studied as substrate for hydrogen production by dark fermentation. During storage and transport of this liquid mixture, inhibitory compounds like acids or alcohol might be produced by endogenous flora. A factorial fractional design based on the composition of the substrate was used to determine the best condition to convert this substrate into hydrogen. First results indicated that the consortium used might convert high quantity of lactate into hydrogen. A batch culture confirmed that lactate was used as the main carbon source and a global yield of 0.4mol_H2·mol_lactate^-1 was obtained. This study demonstrated the ability of the consortium tested to convert different carbon sources (carbohydrates or lactate) with good efficiency. These data represented an important parameter in the prospect of using an industrial substrate whose composition is liable to vary according to the conditions of storage and transport.

Biodrying for municipal solid waste: volume and weight reduction

Biodrying is a variation of aerobic decomposition used for the mechanical-biological treatment organic substances to dry and partially stabilize residual municipal waste. This study focuses on the volume and weight reduction biodegradation of the biodrying process using municipal solid waste and the appearance of a stable, final product. The materials were placed in a reactor with invariant airflow rates of 50 L/h and initial moisture contents of 48.49-50.00%. The laboratory-scale experiments were implemented using a 36-L biodrying reactor equipped with an air supply system, a biomass temperature sensor and air sensors. To determine the effect of temperature on biodrying, the process was repeated at various temperatures between 30 °C and 50 °C. The results obtained indicated that after 13 days, biodrying reduced the volume content of waste by 32% and the final product had a high calorific value (4680 kcal/kg).