Olive mill wastewaters anaerobic bioreactor effluents: a source of valuable biomolecules and enzymes

An anaerobic hybrid digester was applied to treat and valorize energetically the raw olive mill wastewater (OMW), avoiding any previous action of the effluent preparation, through biogas production. The stream obtained from the anaerobic process was investigated in order to assess the potential content of valuable biomolecules in the residual fraction. The study was carried out by evaluating some enzymes normally present in the OMW: lipases, glucosidases, laccases, cellulases and xylanases. Our data showed that by increasing the OMW amount in influent a decrease on lipase concentration was observed; on the contrary, the enzyme concentration in the hybrid digester output was implemented. Increases from about 20 % to 37 % were registered indicating that lipase enzyme was formed inside of the unit. The production of enzymes involved in the hydrolysis of complex carbohydrates (cellulase and xylanase) seems to be higher when the feed mixture contains a greater OMW volume (83 % v/v). These enzymes are still present at 100 % (v/v OMW) even though to a lesser extent as they occurred in traces. It was demonstrated by applying an adequate technological management that it is possible to obtain the OMW bioremediation and a simultaneous production of energy and valuable biomolecules.