**4.3. Technological systems: classification and description**

The bioxidative processes are carried out in different operative systems, classified as (Amirante & Montel, 1999; Clodoveo et al., 2000; Goldstein, 1980; Willson et al., 1980):


The intensive systems are destined to high fermentability biomasses. They are generally closed, dynamic and aired, and works through a first active phase (ACT), with control of process parameters, and a second phase (curing) with lower-level of technological complexity, similar to the extensive systems. The processing times vary between 25-30 and 120 days (in average 90 days). The energetic needs are around 40-60 kwh ton-1 for the machinery power (overturners, ventilation systems, grinders, sieves). The need areas are around 0.7-1.5 m2 ton-1 of annual biomass to process.

The extensive systems are dedicate to biomasses of low fermentability and are open, or also confined, static and not aired (aired for diffusion and natural convection), and do not differentiate the operative phases, but they adopt an only lower technological step. Typically they consist in macropiles open air, without or very time deferred overturns. The process times varying around 6 months up to over 1 year. The energetic needs are low (10-20 kwh ton-1), for the grinding, the optional overturn with generic machines (mechanical shovels) and the sifting. They need surfaces around 1.5 - 2 m2 ton-1 of annual biomass to process.

#### *4.3.1. Systems "closed" or "open"*

In the closed systems the process is carried out in confined spaces (bioreactors) or in covered areas (sheds), for biomasses that require greater control of the fermentative parameters (high moisture, stinking as well as selected for high quality compost). Conversely, the open systems are destined to biomasses of low fermentability, high percentage (i.e. 70%) of lignocelluloses bulking, or for curing phases of biomasses already submitted to ACT.

#### *4.3.2. Systems "static" and "dynamic"*

These systems differ for the periodic or continuous biomass moving (dynamic) or for immobility (static). The base idea of the static systems is not to disturb the growth and the action of the fungi and of the microbial population, maintaining a microecological environment. This situation is important to create in the biomass good growth conditions with the purpose to facilitate the stabilization processes. This systems can work with matrixes well structured and homogeneous, with at least 40 - 50% in weight of lignocelluloses bulking, to avoid the compaction of the mass, and moisture less than 65%.

In the dynamic systems can be processed very moisture matrixes (> 65%) and with less than 30% in weight of lignocelluloses bulking.

### *4.3.3. Systems "aired" and "not aired"*

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

**4.3. Technological systems: classification and description** 

around 0.7-1.5 m2 ton-1 of annual biomass to process.


sifting. They need surfaces around 1.5 - 2 m2 ton-1 of annual biomass to process.

mixers).

energetic needs;

*4.3.1. Systems "closed" or "open"* 

*4.3.2. Systems "static" and "dynamic"* 

The composting process can also carried out with low-tech approaches and extreme operational simplification, excluding the forced airing and effecting the biomass overturns using machineries already in endowment to the farm (choppers, shovel loader, wagon

The bioxidative processes are carried out in different operative systems, classified as (Amirante & Montel, 1999; Clodoveo et al., 2000; Goldstein, 1980; Willson et al., 1980):


The intensive systems are destined to high fermentability biomasses. They are generally closed, dynamic and aired, and works through a first active phase (ACT), with control of process parameters, and a second phase (curing) with lower-level of technological complexity, similar to the extensive systems. The processing times vary between 25-30 and 120 days (in average 90 days). The energetic needs are around 40-60 kwh ton-1 for the machinery power (overturners, ventilation systems, grinders, sieves). The need areas are

The extensive systems are dedicate to biomasses of low fermentability and are open, or also confined, static and not aired (aired for diffusion and natural convection), and do not differentiate the operative phases, but they adopt an only lower technological step. Typically they consist in macropiles open air, without or very time deferred overturns. The process times varying around 6 months up to over 1 year. The energetic needs are low (10-20 kwh ton-1), for the grinding, the optional overturn with generic machines (mechanical shovels) and the

In the closed systems the process is carried out in confined spaces (bioreactors) or in covered areas (sheds), for biomasses that require greater control of the fermentative parameters (high moisture, stinking as well as selected for high quality compost). Conversely, the open systems are destined to biomasses of low fermentability, high percentage (i.e. 70%) of

These systems differ for the periodic or continuous biomass moving (dynamic) or for immobility (static). The base idea of the static systems is not to disturb the growth and the action of the fungi and of the microbial population, maintaining a microecological environment. This situation is important to create in the biomass good growth conditions with the purpose to facilitate the stabilization processes. This systems can work with

lignocelluloses bulking, or for curing phases of biomasses already submitted to ACT.

The forced airing of the biomass is an important factor of optimization of the process particularly for the treatment of low consistence and higher fermentability biomasses. For the optimization of the forced airing it is necessary to calculate and monitoring:


The different processing systems, classified according to the installations or the operational methodology, can be associate to one or more of following categories. Typically, among the open systems are included: Aired static pile; Overturned pile; Short pile. While, among the closed systems they are: Biocontainer; Dynamic trenches; Dynamic basins; Silos.

#### *4.3.4. Aired static pile*

The aired static pile constitute a system of relative technological simplicity. It was developed in America as "Beltsville system ", with the purpose to have a simple system of the wastes biomasses bioconversion to the farmers for agronomic reuse. In his different variations, it shapes as an open, static and aired system (Willson et al., 1980). Typically it foresees the disposition of the biomass in pile, with forced airing in aspiration below the pile and dispatch of the exhausted air to a compost-made biofilter. On the pile surface a layer of mature compost is placed, with not permeable and filtering actions. As static system, it requires of a high percentage of structural lignocelluloses bulking, and of a relatively low moisture of the starting matrix. It also requires a appropriate homogenization pre-

treatments of biomass. In some different systems the forced airing works by inflation, while for the pile coverage are adopted cloths or semi-permeable membranes, to limit the losses of moisture.

Olive Mill By-Products Management 191

the active phase of higher fermentability biomasses or also for whole process (ACT and Curing, without discontinuity). This system result to be economically competitive for

The silos are vertical reactors, to one or multi step, closed and airing, with continuous or discontinuous loading and unloading of the biomass. The system can be static (for batch processes) or semi-dynamic (top loading of composting matrix and bottom unloading of

Several experimental trials were carried out using different olive mill typology wastes (two phase mill fluid pomace; three phase mill pomace and waste water), mixed with others agricultural or agroindustrial byproducts, with the aim to evaluate both the composting process efficiency, and the amendment and nutritional efficiency of obtained composts on: i) maintain or improving soil properties and soil fertility; ii) growth and yield performance of herbaceous crops; iii) growth and yield performance of olive orchards (Albuquerque et al., 2007; Alfano et al, 2008; Baeta-Hall et al., 2005; Boulter et al., 2000; Calvet et al., 1985; Casacchia et al., 2012; Diacono & Montemurro, 2010; Hoitink et al., 1997; Montemurro et al.,

In some experimental trials, the assessment of the composting process in natural conditions was studied on two different typology of matrices, respectively composed by olive mill wastes and other crop by-products as structural biomass: i) wet pomace by two phases mill with olive leaves and cereals straw; ii) pomace and waste water by three phases mill with carved pruning residuals. All materials were placed on a beaten-soil platform, and remixed to homogenize the matrices. The evolution of bioxidation was monitored controlling the temperature and humidity of matrices, and assuring oxygenation and thermal drain by weekly blending with mechanical shovel on tractor front loader. At the end of the fermentation period, both biomass microbial pools and chemical parameters were analyzed to evaluate the characteristics of obtained composts. Results of composting parameters trend and microbiological analysis, indicate a correct way of aerobic process; and the compost analyses confirmed that a "mixed composted amendments" was obtained (Law 748/1984).

To evaluate amendment and nutritional efficiency, the composts were spread at doses of approx. 150 kg tree-1 (60 tons ha-1) on 6 x 4 scaled olive orchard, and buried with a light disk arrow tillage. At the following year's harvesting time, was compared the differences between treated and untreated soil characteristics, and yield responses of 15 treated vs. 15 untreated olive trees of a 15 years old "Nocellara messinese" cultivar for OP2 compost, and

2004, 2006, 2010, 2011*b*; Tejada et al., 2006, 2009; Toscano et al., 2009 *b*).

processing over 100 tons day-1 of biomasses.

**5. Composting experiences and results** 

**5.1. Results on olive orchards** 

20 years old "Leccino" cultivar for OP3 compost.

*4.3.10. Silos* 

stabilized biomass).

#### *4.3.5. Overturned piles*

In this system the biomass are disposed in piles of great dimensions (3-4 m of height; width up to over 20 m). The piles are typically open, not aired and overturned with ample intervals (weeks or months), with mechanical shovels or specific overturning machines in the case of continuous systems. This system is adopted for matrixes to tall prevalence of lignocelluloses material (green residues) or in the curing of biomasses after the ACT. The piles can be managed in batch, or in continuous, with progressive translation of the biomass during the overturns, toward the unloading section. This second solution eliminates the unused spaces between piles, while is forcing to adopt a fixed overturns periodicity, that would not correspond to the real needs of process.

#### *4.3.6. Short pile*

The short pile differ from the piles for their smaller dimensions (max 2.5 m height) and can be or not endowed with the forced airing. The overturn is generally frequent (from few days up to daily intervals) and are made with specific overturners. The short piles are planned as "closed system" for the active phase of high fermentable matrixes; or as "open" where the stinking impacts do not constitute trouble, or for low fermentable material, or for the curing of end-fermented biomasses.

#### *4.3.7. Biocontainer and biocell*

Biocontainer and biocell are horizontal closed reactors, typically static and airing. The biomass is placed in beds of the maximum height of around 3 meters. The biocontainer are made with metallic or concrete, insulate, and have unitary volumes of the order of many about ten cubic meters. These systems generally adopt the recycle of the air, and survey systems to manage the parameters of process (moisture, oxygen percentage in the inside atmosphere, temperature) and feed-back regulation of the air flows and the percentages of air recycle.

#### *4.3.8. Dynamic trenches*

Conversely to the biocontainer, in this system the reactor is divided in trenches served by one or more lines of forced airing, with modulation of the air flows in the different sections correspondents to the different times of process. The trenches race binary for the translation of self-moving overturners that also effect the progressive transfer of biomass (continuous system). The trenches are typically used for the management of the active phases of biomasses to elevated fermentability, in closed environments. As dynamic system, can effectively process also biomasses with high moisture content.

#### *4.3.9. Dynamic basins*

In this installation typology, typically closed, aired and dynamic, the composting biomass is placed in basins, and moved with special self-moving overturners. It is generally used for the active phase of higher fermentability biomasses or also for whole process (ACT and Curing, without discontinuity). This system result to be economically competitive for processing over 100 tons day-1 of biomasses.

*4.3.10. Silos* 

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

would not correspond to the real needs of process.

moisture.

*4.3.5. Overturned piles* 

*4.3.6. Short pile* 

air recycle.

*4.3.8. Dynamic trenches* 

*4.3.9. Dynamic basins* 

of end-fermented biomasses. *4.3.7. Biocontainer and biocell* 

treatments of biomass. In some different systems the forced airing works by inflation, while for the pile coverage are adopted cloths or semi-permeable membranes, to limit the losses of

In this system the biomass are disposed in piles of great dimensions (3-4 m of height; width up to over 20 m). The piles are typically open, not aired and overturned with ample intervals (weeks or months), with mechanical shovels or specific overturning machines in the case of continuous systems. This system is adopted for matrixes to tall prevalence of lignocelluloses material (green residues) or in the curing of biomasses after the ACT. The piles can be managed in batch, or in continuous, with progressive translation of the biomass during the overturns, toward the unloading section. This second solution eliminates the unused spaces between piles, while is forcing to adopt a fixed overturns periodicity, that

The short pile differ from the piles for their smaller dimensions (max 2.5 m height) and can be or not endowed with the forced airing. The overturn is generally frequent (from few days up to daily intervals) and are made with specific overturners. The short piles are planned as "closed system" for the active phase of high fermentable matrixes; or as "open" where the stinking impacts do not constitute trouble, or for low fermentable material, or for the curing

Biocontainer and biocell are horizontal closed reactors, typically static and airing. The biomass is placed in beds of the maximum height of around 3 meters. The biocontainer are made with metallic or concrete, insulate, and have unitary volumes of the order of many about ten cubic meters. These systems generally adopt the recycle of the air, and survey systems to manage the parameters of process (moisture, oxygen percentage in the inside atmosphere, temperature) and feed-back regulation of the air flows and the percentages of

Conversely to the biocontainer, in this system the reactor is divided in trenches served by one or more lines of forced airing, with modulation of the air flows in the different sections correspondents to the different times of process. The trenches race binary for the translation of self-moving overturners that also effect the progressive transfer of biomass (continuous system). The trenches are typically used for the management of the active phases of biomasses to elevated fermentability, in closed environments. As dynamic system, can

In this installation typology, typically closed, aired and dynamic, the composting biomass is placed in basins, and moved with special self-moving overturners. It is generally used for

effectively process also biomasses with high moisture content.

The silos are vertical reactors, to one or multi step, closed and airing, with continuous or discontinuous loading and unloading of the biomass. The system can be static (for batch processes) or semi-dynamic (top loading of composting matrix and bottom unloading of stabilized biomass).
