IMPROVEMENT OF THE METHANE YIELD FROM THE SLUDGE BY CO-DIGESTION WITH DROMEDARY DUNG IN THE CITY OF ADRAR IN ALGERIA

The sludge in Adrar, a city located in southwestern Algeria, was co-digested with dromedary dung from the same region. For this, five batch-type digesters with a reaction volume of 1 L and different proportions of substrate were used. The proportions of sludge to dromedary manure substrates were: 0/100, 25/75, 50/50, 75/25 and 100/0. The substrate concentration in the digesters was fixed at 16 g / L of organic matter, with an inoculum to substrate ratio equal to 2/1. Digestion has gone through the mesophilic phase (37 +/- 2 degrees C), with a unified hydraulic retention time of 30 days for all digesters. The volumes of biogas and methane were measured every day during the total period of the experiments, using the biochemical methane potential (BMP) test, pH, and volatile fatty acids (VFA) assay. In addition, the full alkalimetric titer (FAT) was recorded every week, and the organic matter content and the chemical oxygen demand (COD) were registered before and after each experiment. The results obtained showed that for the proportions of 25% of dromedary manure and 75% of sludge allowed having a good anaerobic digestion, which explains the good chemical oxygen demand obtained (32000 - 11666 mg / l). This resulted in the production of large amounts of biogas (1439 ml) and methane (909 ml), with a significant consumption of substrate (45.93%) in comparison with the other proportions used.