**4. Composting**

The composting is a controlled process, based on the control of the natural bioxidative process on organic substances (Figure 1) transformed by aerobes microorganisms naturally present in the environment and in the matrixes, in a stabilized and sanitized organic substance, defined compost (Casacchia et al., 2011; Insam & De Bertoldi, 2007).

The composting is classified by the law (Legislative Decree 22/97) as a recovery operation of byproducts, among the actions of "The recycle and/or retrieve of the organic substances not used as solvents"; being an interesting alternative in recycling large amounts of a wide range of the residues produced in Mediterranean areas, resulting in an organic fertilizer suitable to agricultural purposes, in improvement of o. m. content of soils, and reduction of fertilization costs.

The composting process is usually divided in two phases: Active Composting Time (ACT), and Curing.

During the ACT, there is an intense develop of degradative processes on to more easily fermentescible organic components. In this thermophylic phase the biomass reaches temperatures up to 65 °C, that also allow its hygienization. The ACT can develop, according to the characteristics of the matrix, in piles, with or without overturn and with or without forced airing, or in more complex systems (bioreactors), and varying from 21-28 days in the first case or 14-16 days in the second one.

During the curing phase, the degradative phenomena will be completed, and the synthesis of the humic-like substances occurred. This process, which has a duration of more than 45 days, need a smaller oxygen and drain of heat.

The main parameters of the composting process, that ensure an optimal development of microorganism able to transform the organic matrices, are synthetically reported in Table 4.


**Table 4.** Controllable composting parameters.

182 Olive Germplasm – The Olive Cultivation, Table Olive and Olive Oil Industry in Italy

With this definition, are indicated the processes and the activities on organic materials that, degraded and transformed by various decomposers microorganisms, allow its stabilization in terms of mineralization of the mostly degradable components, and the hygienization of

The biological treatment of byproducts can be realized with different technologies and



The composting is a controlled process, based on the control of the natural bioxidative process on organic substances (Figure 1) transformed by aerobes microorganisms naturally present in the environment and in the matrixes, in a stabilized and sanitized organic

The composting is classified by the law (Legislative Decree 22/97) as a recovery operation of byproducts, among the actions of "The recycle and/or retrieve of the organic substances not used as solvents"; being an interesting alternative in recycling large amounts of a wide range of the residues produced in Mediterranean areas, resulting in an organic fertilizer suitable to agricultural purposes, in improvement of o. m. content of soils, and reduction of

The composting process is usually divided in two phases: Active Composting Time (ACT),

During the ACT, there is an intense develop of degradative processes on to more easily fermentescible organic components. In this thermophylic phase the biomass reaches temperatures up to 65 °C, that also allow its hygienization. The ACT can develop, according to the characteristics of the matrix, in piles, with or without overturn and with or without forced airing, or in more complex systems (bioreactors), and varying from 21-28 days in the

During the curing phase, the degradative phenomena will be completed, and the synthesis of the humic-like substances occurred. This process, which has a duration of more than 45

substance, defined compost (Casacchia et al., 2011; Insam & De Bertoldi, 2007).

**3. Biological treatments** 

the biomass by pasteurization.

sludge usage in agriculture.

first case or 14-16 days in the second one.

days, need a smaller oxygen and drain of heat.

fertilizers;

**4. Composting** 

fertilization costs.

and Curing.

processes, referable to three following typologies:

During the composting, the organic substance evolves both quantitatively, reducing weight and volume, and qualitatively, with deep modifications of its chemical and structural characteristics. The parameters that defines the composted materials are:


In order to the duration of the fermentative process, two typologies of compost can be obtained, based on their degree of maturation:


Olive Mill By-Products Management 185

fraction (bulking); while greater intervals (up to 10-15 days) can be applied on more porous

The composting practices contemplate several operative options, in relationship to the different typologies of biomasses to be treated, and to the different managerial and environmental situations: from the simplest systems of aerobic stabilization on natural conditions, up to the industrial plants with the complete control of the process conditions (Alfano et al., 2008; Amirante & Montel, 1999; Baeta-Hall et al., 2005; Calvet et al., 1985; De Bertoldi et al., 1983; Diaz et al., 2007; Madejon et al., 1998; Montemurro et al., 2009; Tomati et

Although the OP is characterized from inadequate physical characteristics, in particular the OP2, that makes difficult the aerobic degradation, this by-product can be easily composted by using complementary residues such as pruning residues or cereal straw as bulking agents; also mixed with other agricultural wastes as animal manures or horticultural residues. During the process, the potentially dangerous organic substances in the olive wastes are degraded, allowing the safe and useful use of the obtained compost in

The composting sector is disciplined by the two following normatives: the wastes normative, that defines the conditions of production of the compost from wastes or selected fractions, and the fertilizers one that establish the marketing conditions of the compost.


The Legislative Decree 22/97, which follows the CEE/91/156 wastes directive, classifies the composting among the recovery operations of wastes (Annex "C", R3: Recycle/recovery of the organic substances not used as solvents, included the composting operations and other

With the Technical Normative, the D. M. 05.02.1998, have been defined the technical aspects tied up to the compost production, even if limited to the activities of recovery in simplified regime, with a reference to the Law 748/84 "Norms for the fertilizers discipline", that in the enclosure 1C, as modified by the D.M. 27.03.1998, defines the marketing characteristics for


procedures to the senses of the artts. 31 and 33 of the Legislative Decree 22/97. - Fertilizers Normative: Law 748/84 (Annex 1C) and modifications and integrations.

or coarse matrixes, and in the curing phase of compost.

agricultural fields; and valorizing these byproducts as a resource.

the compost, indicating the following four types of final products:

al., 1996; Veronesi & Zampighi, 1997).

**4.1. Composting normative** 

biological transformations).

material for composts);

**Figure 1.** Composting process flow.

The composting of the agro industrial by-products and agricultural residual biomasses can be carried out according to two typologies:


The on-farm composting does not require particular technologies, while the necessary machineries (carver, shovel loader, wagon mixer) are often already present in farm.

The biomasses to be composted, mixed with opportune percentages of appropriate structural and absorbent fractions (lignocelluloses bulking), are typically placed in pile on paved stage, preferably covered, and periodically overturned up to stabilization.

The shape and the dimensions of the pile will depend from the quantity and the quality of the material to be treated. The forms are of triangular, parabolic or trapezoidal section, of 1.5 - 1.8 m height, while width and length depending from the quantity of material or from the available space, and also in base to the machinery used for the overturns (hauled or self moving over-turner, shovel loader).

During the composting, must be constantly monitored temperature and moisture of the pile, taking care of maintain the porosity, to allow the aeration and thermic dispersion of biomass.

According to the moisture and granulometry of biomass, the overturns will have to take place to intervals of 2-3 days, in case of high moisture or low percentage of structural fraction (bulking); while greater intervals (up to 10-15 days) can be applied on more porous or coarse matrixes, and in the curing phase of compost.

The composting practices contemplate several operative options, in relationship to the different typologies of biomasses to be treated, and to the different managerial and environmental situations: from the simplest systems of aerobic stabilization on natural conditions, up to the industrial plants with the complete control of the process conditions (Alfano et al., 2008; Amirante & Montel, 1999; Baeta-Hall et al., 2005; Calvet et al., 1985; De Bertoldi et al., 1983; Diaz et al., 2007; Madejon et al., 1998; Montemurro et al., 2009; Tomati et al., 1996; Veronesi & Zampighi, 1997).

Although the OP is characterized from inadequate physical characteristics, in particular the OP2, that makes difficult the aerobic degradation, this by-product can be easily composted by using complementary residues such as pruning residues or cereal straw as bulking agents; also mixed with other agricultural wastes as animal manures or horticultural residues. During the process, the potentially dangerous organic substances in the olive wastes are degraded, allowing the safe and useful use of the obtained compost in agricultural fields; and valorizing these byproducts as a resource.
