The objective of this laboratory-scale experimental work is to investigate the biogas production potential of two different substrates, namely poultry manure and a chosen agricultural residue (sun flower hulls), via mesophilic anaerobic co-digestion process, using batch-scale systems. This paper summarizes the preliminary results from the ongoing experiments.

Agrifood industry plays a relevant role in the economic development of the Autonomous Community of Extremadura (Spain), and generates vast volumes of wastes featured by both high polluting potential and moisture content. The present work reports on a detailed analysis of biogas generation (as well as of the relative methane and carbon dioxide production per ton waste) from the anaerobic digestion of industrial tomato residues and slaughterhouse wastes. For such purpose, the annual waste generation rates in Extremadura were taken as input data; the methane and carbon dioxide volumes per ton waste were assumed as those of the hypothetical case of wastes being naturally decomposed; and the obtained biogas was regarded to serve as fuel for useful energy production (heat and/or electricity). Under these assumptions, the environmental benefit of the anaerobic digestion of the wastes was quantified and compared with the greenhouse emissions that might be observed if such wastes were directly dumped to the environment.

This paper describes anaerobic conversion of Jatropha curcas seed cake at 30˚C in a five - liter working volume reactor. The aim of this work was to investigate the effectiveness of employing a batch process to produce biogas and evaluate the performance of the process in terms of methane yield and extent of degradation. Initially fresh cow dung slurry culture was inoculated in five reactors for culture development. The seed cake was prepared as a slurry at ratios of 1:20, 1:10, 1:6.67, 1:5 and 1:4 by weight with tap water. Over a 60-day operating period, a slurry of seed cake in water at a ratio of 1:20 showed the highest methane yield of 296 liter methane at STP/kg COD degraded (or 156 liter at STP/kg of Jatropha curcas seed cake added) and was achieved with 52% COD removal efficiency. The results revealed that Jatropha curcas seed cake treated anaerobically can be a good source of methane production. At the tested concentration, the appropriate seed cake-to-water ratio for methane production should be in the range of 1:20 to 1:10.