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Identifier 000456736
Title Βιοαποικοδόμηση ολικού φαινολικού φορτίου υγρών αποβλήτων ελαιοτριβείων (κατσίγαρος) και παραγωγή ενέργειας από αυτά με τη μορφή αέριου υδρογόνου (Η2)
Author Παππάς, Ιωάννης Ν.
Thesis advisor Κοτζαμπάσης, Κυριάκος
Reviewer Βόντας, Ιωάννης
Πυρίντσος, Στέργιος
Abstract Wastewater from olive oil mills has significant polluting properties, especially due to the high concentration of aromatic compounds (mainly phenolics). The current project aims to study the biodegradation of the total phenolic compounds in olive mills wastewater (OMW) by algae, taking into account their bioenergetic strategy to biodegradate phenols (Papazi and Kotzabasis,2007, 2008). In the meanwhile we tried to test the possibility to use the biodegradation of the total phenolic compounds in OMW by algae as electrons source for transferring electrons through the photosynthetic electron flow to hydrogenase yielding large amounts of H2 according to the mechanism recently has been described by Papazi et al. (2012). To exclude the randomness of the results, we used individual samples of OMW from 14 different mills around Greece. The results have shown that the pH adjustment is the key not only for the biodegradation of the total phenolic compounds but also for the production of molecular hydrogen. When the acidic pH (pH 4-5) was configured at pH> 6,5, significant levels of molecular hydrogen production and high biodegradation of total phenolic compounds in OMW (in closed systems), were observed. This study has clearly demonstrated that the two processes (production of H2 and biodegradation of toxic phenolic compounds) are competitive, since the biodegradation of the total phenolic compound requires the presence of oxygen [because of the essential need of (mono) oxygenases in the biochemical pathways which are involved in the biodegradation of phenols], and the production of molecular hydrogen needs anoxic conditions to start. Samples of OMW (mixture of the 14 mills around Greece), which were incubated in closed and open systems, have clearly shown that the biodegradation of the total phenolic compounds in open systems is complete (100% degradation of the total phenolic compound), in a period of 7 days of incubation, with and without additional algae (Scenedesmus obliquus). The fact, there was 100% biodegradation in algae free treatments, revealed the existence of specific micro flora (algae, cyanobacteria, bacteria, ...) in the OMW which remains inactive, mainly due to the acidic pH of OMW. The pH adjustment of OMW to pH: 6,5 or higher, activates the metabolism of these organisms, inducing the biodegradation of toxic phenolic compounds. In closed systems the activation of metabolism leads to the establishment of anoxic conditions and induces H2 production. Although the addition of algae contributes to this process, it seems it is not necessary! It seems that the micro flora in OMW is able under certain conditions to produce molecular hydrogen and detoxificate the total of the phenolic compounds in OMW. All we have to do is create the proper conditions (pH regulation, closed or open system, etc.), and the OMW’s micro flora itself can fully biodegrade the total of the phenolic compounds in OMW and at the same time can produce high amounts of H2. The results of the present study give for first time the possibility to use a complete detoxification method of OMW at the place of olive oil production (in each mill), with simultaneous production of high amount of hydrogen which could used as an energy source. In addition to the environmental compatibility and the sustainability of the process, the cost / benefit ratio appears to be very appealing and ensures a wide use in the Mediterranean region and especially here in Crete in the near future.
Language Greek
Issue date 2016-11-18
Collection   School/Department--School of Sciences and Engineering--Department of Biology--Post-graduate theses
  Type of Work--Post-graduate theses
Permanent Link https://elocus.lib.uoc.gr//dlib/f/e/e/metadata-dlib-1687945761-411798-30961.tkl Bookmark and Share
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