Start-up test of an underground digester treating organic waste

In this paper we studied the start-up of an underground digester with a useful volume of 4 m³ in Saharan medium. 320 kg of waste taken from Adrar city slaughterhouses were treated during 60 days. During this study, we followed several parameters evolution such as: pH, volatile fatty acid (VFA), the temperature inside the digester, chemical oxygen demand (COD), pressure and the volume of biogas produced. The results obtained showed in the beginning of anaerobic digestion a fast drop in the pH. The VFA variation was inversely proportional to the pH variation. We noted a temperature decrease inside the digester during hydrolysis phase. Biogas inflammability was obtained since the 25^th day of digestion. The results showed also an organic mater reduction in order of 49%.