Anaerobic digestion of olive mill wastewaters in fully mixed reactors and in fixed film reactors

Abstract

Calcium hydroxide precipitates phenolic compounds and long chain fatty acids toxic to methanogenic bacteria, and improves the total alkalinity; it is therfore better for the adjustment of the pH of olive mill wastewaters (OMW) than sodium hydroxide. The fully mixed reactors are adequate for volatile fatty acid production from OMW, although an anaerobic filter is advisable for methanogenesis. The anaerobic filter filled with a clay media matrix which is less porous and has a larger specific area than PVC, gives a quick start-up and a satisfactory performance.