**3. Biological treatments**

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 biomass by pasteurization.

Olive Mill By-Products Management 183

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.

pH Should be between 5.5 - 8, to assure the activity of useful microbes. Humidity % Range variable from 50-60% in the first weeks (ACT); to go down to

Temperature Range to develop microorganism: 40-45 °C (3 days over 55 °C for the

C/N ratio Nutrient balance: between 25 and 35 to avoid nitrogen losses for

O2 concentration Assured by forced airing and/or overturns. Optimal range for

During the composting, the organic substance evolves both quantitatively, reducing weight and volume, and qualitatively, with deep modifications of its chemical and structural




In order to the duration of the fermentative process, two typologies of compost can be



maturity is detected by the phytotoxicity, verifiable with the homonym test.

and the processing typology.

Italian legislation, to kill pathogens)

Porosity To ensure aerobic process; depending on particle size. The better air-filled pore space: 25-50%

degradative process: 15-20%

characteristics. The parameters that defines the composted materials are:

activity (low static and/or dynamic respiration index).

1988; Franz et al., 2005; IPLA, 1992; Zucconi et al., 1981).

obtained, based on their degree of maturation:

and before the transplantation;

nursery.

Particle size Surface air for microbial growth

**Table 4.** Controllable composting parameters.

30-35% to the end of process, depending on the biomass characteristics

volatilization (< 25) or decrease speed of metabolic reactions (> 35)

The biological treatment of byproducts can be realized with different technologies and processes, referable to three following typologies:

