**3. Conclusions**

The use of yeasts for the bioremediation of OMW is a promising and open way; the starting question of this paper was: why yeasts?

We can try to point out some-key elements/benefit for the use of yeasts in OMW:

**1.** yeasts represent the dominant microflora of OMW and many strains are well adapted and able to grow in this stressful environment;

**2.** yeasts can be used for the aerobic and anaerobic treatment of wastes;

studied for different parameters) is quite difficult and complex. A possible solution could be the use of multivariate statistical approaches, like the Principal Component Analysis, Cluster

The main result of the multivariate approach is the choice of the best strains (3-10) for an *in vivo* validation; however, yeasts require a preliminary optimization and/or validation in small

**1. Use of coadjutants**. It has been reported that yeast metabolism could be enhanced by the addition of some ingredients; for example, Sinigaglia et al. [55] proposed the use of (NH4)2SO4 (1.5-6.0 g/L), while authors of the reference [46] used hexadecane and yeast

**2. Temperature and shaking**. Some authors [46, 58] proposed a bioremediation with agitation (100-150 rpm) and at relatively high temperatures to increase the yield of the

**3. State of cells (free or immobilized in a bioreactor)**. OMW can be detoxified by free cells, as proposed by many authors or using the novel method proposed in the reference [46], who loaded a strain of *Geotrichum candidum* in Na-alginate beads and increased by 2-2.2

**4. Use of a single strain or a multiple strain starter**. The use of a multiple strain starter could be a promising way to enhance the yield and avoid a stop in the detoxification; thus, validation should focus on the composition of the starter (amounts of the different strains)

**5. OMW dilution**. It was proposed a 10-fold dilution to increase fungal bioremediation by *Aspergillus wentii*, *A niger* and *Pleurotus ostreatus* [67] and these data were confirmed by a preliminary investigation performed on yeasts on our laboratory with a 3-fold dilution.

**6. Kind of process (aerobic or anaerobic)**.The use of an aerobic step could increase the yield [68]. The authors of the reference a preliminary and aerobic step with *G. candidum* to reduce COD and phenolic and fatty acid contents and increase substrate up-taking during

The use of yeasts for the bioremediation of OMW is a promising and open way; the starting

**1.** yeasts represent the dominant microflora of OMW and many strains are well adapted and

We can try to point out some-key elements/benefit for the use of yeasts in OMW:

and the way of inoculation (single inoculum or step-by-step inoculum).

Analysis or Multiple Correspondence Analysis or all of them in a sequence.

volumes and under controlled conditions.

58 Applied Bioremediation - Active and Passive Approaches

Some variables that should be assessed are:

extract.

process.

fold the yield of removal.

the anaerobic treatment.

question of this paper was: why yeasts?

able to grow in this stressful environment;

**3. Conclusions**


10

**Figure 1.** Selection of yeasts for phenol removal in OMW


[2] Migliorini P. Development of Organic Olive Cultivation and its Importance for the Sustainability in the Mediterranean. In: Migliorini P., Minotou C., Lusic D., Hashem Y., Martinis A. (eds.) Book of Abstract. International Conference on ORGANIC AG‐ RICULTURE and AGRO-ECO TOURSIM in the Mediterranean, International Confer‐

Bioremediation of Olive Mill Wastewater by Yeasts – A Review of the Criteria for the Selection of Promising Strains

http://dx.doi.org/10.5772/56916

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**Table 2.** Technological and taxonomic characterization

#### **Acknowledgements**

This research was supported by project ECO\_P4 PON02\_00186\_2866121 (Promotion of ECOfriendly processes for the enhancement of quality of Apulian food productions), granted by the Italian Ministry of Education, University and Research.

### **Author details**

Antonio Bevilacqua\* , Leonardo Petruzzi, Maria Rosaria Corbo and Milena Sinigaglia

\*Address all correspondence to: antonio.bevilacqua@unifg.it

Department of the Science of Agriculture, Food and Environment, University of Foggia, Foggia, Italy

#### **References**

[1] Tsagaraki E, Harris N, Lazarides, and Konstantinos B. Petrotos. Olive Mill Wastewa‐ ter Treatment. In: Oreopoulou V., Russ W. (eds.) Utilization of By-Products and Treatment of Waste in the Food Industry. New York: Springer; 2007. p. 133-158.

[2] Migliorini P. Development of Organic Olive Cultivation and its Importance for the Sustainability in the Mediterranean. In: Migliorini P., Minotou C., Lusic D., Hashem Y., Martinis A. (eds.) Book of Abstract. International Conference on ORGANIC AG‐ RICULTURE and AGRO-ECO TOURSIM in the Mediterranean, International Confer‐ ence AgriBioMediterraneo, 16-18 September 2011, Zakynthos, Greece.

**Taxonomy** Spore production **Growth requirements** Nitrogen assimilation Phenol assimilation Growth in OMW

Effect of temperature and pH

Hydrolysis of pectins and xylans

Polyphenoloxydase activity Peroxidase activity

**Acknowledgements**

**Author details**

Antonio Bevilacqua\*

Foggia, Italy

**References**

**Table 2.** Technological and taxonomic characterization

60 Applied Bioremediation - Active and Passive Approaches

the Italian Ministry of Education, University and Research.

\*Address all correspondence to: antonio.bevilacqua@unifg.it

This research was supported by project ECO\_P4 PON02\_00186\_2866121 (Promotion of ECOfriendly processes for the enhancement of quality of Apulian food productions), granted by

Department of the Science of Agriculture, Food and Environment, University of Foggia,

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, Leonardo Petruzzi, Maria Rosaria Corbo and Milena Sinigaglia

**Enzymatic traits** Catalase activity

Cellulolytic activity Lipolytic activity Protease activity


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**Chapter 4**

**Nutrients and Organic Matter Removal in**

Constructed wetlands are promising engineering technique that reproduce the conditions of the natural wetlands [1]. They have high water treatment capacity because of the intensive "work" of the plants and the microorganisms. Depending on the conditions various types of plants are growing: common reed (*Phragmites australis*), rush (*Typha latifolia*), iris, etc. (Fig. 1). These plants are stable toward the climatic changes and the quality parameters of the medium in which they are growing. The metabolism of the microorganisms plays an important role in the pollutants removal from wastewaters. The main chemical and physical processes are sedimentation, sorption, chemical oxidation, photo degradation, evaporation [2] as well as biotic processes such as aerobic/anaerobic degradation, plants accumulation, phytodegradation, phytoevaporation. Many publica‐ tions demonstrate the removal of suspended solids, organic matter, nutrients and bacte‐ ria from wastewater in constructed wetlands. There are two types of constructed wetlands: *surface flow wetlands systems* and *subsurface flow wetland systems*. The latter are subsurface horizontal flow wetlands systems (Fig. 2) and subsurface vertical flow wetland systems (Fig. 3), [3-6]. They are characterized with the different extent of nutrients removal [7-10].

In the subsurface vertical-flow constructed wetlands (SSVFCW) the wastewater enters through the surface and flows in vertical direction slowly through the supporting material and the plant roots until reaching the bottom outlet zone. These systems are built with porous materials such as sand and gravel, that restrict the clogging. The package clogging was observed at high organic load of the system [11]. The recirculation of the wastewater is helpful to overcome this

> © 2013 Lavrova and Koumanova; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**a Vertical-Flow Constructed Wetland**

Silviya Lavrova and Bogdana Koumanova

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/56245

**1. Introduction**

limitation.

