**Author details**

*Humic Substances*

**6. Conclusion**

elements such as Zn, Cu, Ca and Cr, etc. The only exception is observed in case of the WWTPs sludge (A10, A11, and A12) with very high values of these last elements

For the co-composting procedure treated with olive mill wastewater, we necessity assumes the improvement of the potassium and calcium contents of the finished product by assuming the great richness of the olive mill wastewater in these elements. A contrary result could be made and suggested that these nutrients have leaching with the rain in the case of processes conducted without shelter or during watering, especially in the case of potassium, which is the most soluble and

In the same manner, it is advisable to use straws (windrows: A16, A15 and A14) for composting on condition that more water or olive mill wastewater is used for watering and for avoiding low-slung water content at the start of the process that

Finally, industrial technology systems could therefore exploit the olive mill wastewater, which is considered as a precious raw material, very rich in organic matter and nutrients, in order to use them instead of water for watering the wind-

Thus, the problem of the valorisation of the various organic residues, principally of the municipal wastes and olive mill wastewater, is currently worldwide worrying, and it is specially posed in terms of environmental preservation. The choice of the treatment technique must not be only from the point of view of monetary profitability, but above all must consider the efficiency of the treatment process. It is not possible to develop all the techniques currently being tested. Composting appeared as the main pathways for remediating this high and gigantic tonnage of wastes daily generated by modern societies. The processes of composting described above appeared very simple to be implemented, not expensive, and especially gave a finished product of good quality on average, but very consuming in space and in time. At last, I could clearly see that this kind of process might go well with an implantation especially in developing countries with a sunny and warm climate. The amendment of agricultural soil with organic matter is made very urgent by the flagrant lack of its substances on the market and the same demand for fertilisers from the increasingly demanding crops. Soil and the various bio-physico-chemical and especially biological processes of degradation and humification prevailing in the soil contribute intensively and could help in the solution of this thorny problem

that are often proven conform to the common standards in vigor.

therefore the most altered by leaching.

rows during overall composting process.

slows down the general process of composting.

of accumulation of all organic residues in modern societies.

**60**

Wafa Hassen1 \*, Bilel Hassen2 , Rim Werhani3 , Yassine Hidri4 and Abdennaceur Hassen3

1 Research Unit of Analysis and Process Applied to the Environmental (APAE), Higher Institute of Applied Sciences and Technology Mahdia, University of Monastir, Tunisia

2 University of Tunis El Manar, Institute for Veterinary Research of Tunisia, Tunis, Tunisia

3 Water Research and Technology Center (C.E.R.T. E), Borj-Cédria Technology Park, Soliman, Tunisia

4 Laboratory of Integrated Olive Production (LR16IO3), Sousse, Tunisia

\*Address all correspondence to: hassen.wafa@gmail.com

© 2021 The Author(s). Licensee IntechOpen. This chapter is 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.
