PRODUCTION OF POLY-HYDROXYALKANOATES (PHAs) FROM THREE PHASE OLIVE OIL MILL WASTEWATER AT A TWO SCAGE SEMI-PILOT SCALE SYSTEM

摘要

The aim of the present study was to investigate the operational efficiency of a semi-pilot scale PHAs producing system from acidified olive oil mill wastewater (OOMW). An anaerobic acidogenic culture was initially used for the acidification of the wastewater, in a continuous reactor. Subsequently, the effluent was fed to an aerobic reactor operated in sequential batch mode under nutrient limitation. In the second reactor volatile fatty acids were used selectively as carbon source for an enriched culture of Pseudomonas sp., resulting thus to intracellular poly-hydroxyalkanoates (PHAs) formation. The PHAs accumulating system was operated with two types of acidified OOMW as feed, i.e with OOMW after sedimentation of solids and with OOMW after precipitation of the solids by means of aluminium sulphate. It was shown that the obtained % of PHAs in the final biomass was quite higher in the second case, reaching ～ 15.5 % (g PHAs/100 g of VSS). However the characteristics of the PHAs were the same in both cases. The polymer was 3-hydroxybutyrate copolymerized with 3-hydroxyvalerate units, and had an average molecular weight (Mw) of around 490 KDa.