Treatment of olive oil processing wastewater by ultrafiltration, nanofiltration, reverse osmosis and biofiltration

This paper deals with the possibility to purify olive mill wastewater streams from olive mills by means of coagulation, membrane technology and bio filtration. In the last decade, membrane processes have gained a main role to seek for a viable process to treat olive mill wastewater streams due to their capability to eliminate almost all of the pollutants in the water. One main drawback to this approach is the severe membrane fouling issues, that reduces sensibly these capabilities within a short period of time. In order to inhibit the fouling formation, in this work the boundary flux approach was used, that is the determination of proper operating conditions that do not promote fouling formation by specific measurements and modelling. Nevertheless, membranes may not be sufficient to reach the desired purification grade of the wastewater stream for a harmless disposal in the environment. Novelty of this work is the last process step, that is bio filtration and was accomplished by means of a biofilter. This step is necessary in order to guarantee the achievement of a treated water to a quality grade compatible to the discharge in superficial aquifers. The adopted system is compact, have small residence times and is capable to treat the RO permeate to the target values. The experimental work will be discussed and reported in this paper.