**2. Experimental**

In a first stage, the products under investigation were characterized as derived from the industrial process. The results of the characterization were utilized to set up preliminary tests on waste processing, in particular the comminution operations were evaluated. Finally, an experimental plan was carried out to assess the feasibility of waste recycling.

#### **2.1 Methods for characterization**

The following methods were adopted in the experimental set-up for the characterization of products under investigation:


#### **2.1.1 Image analysis**

The images for characterization were acquired by the stereoscopic microscopy Leica Wild M8 and a by a digital camera Olympus C-5060 Wide Zoom. The image analysis was carried out by the software SigmaScan Pro© Version 5.0.0 (Systat Software Inc., 2007), which provides a complete set of tools to analyse structure and dimension of an object's image.

Firstly, calibration allowed to convert image unit from pixel to millimetre (Figure 1). After calibration, the image quality for data elaboration has been enhanced, increasing the

The use of environmental-friendly packaging (i.e. recyclable or degradable packaging) has to be considered. Valuable packaging materials, such as aluminium paper, glass and plastic materials, can been extensively recycled if they have not been in contact with toxic or

This chapter is focused on a feasibility study for the management of packaging waste from a

• bottles in high density polyethylene (HDPE), for suspension to be reconstituted;

• flexible multi-layered (plastic and aluminium) sachets containing granular medicine.

In a first stage, the products under investigation were characterized as derived from the industrial process. The results of the characterization were utilized to set up preliminary tests on waste processing, in particular the comminution operations were evaluated. Finally,

The following methods were adopted in the experimental set-up for the characterization of

• image analysis, to measure geometric and morphologic characteristics; the results were

• laser granulometry, to classify size distribution of particles in the interval between 0.1 e

• infrared spectroscopy, to recognize chemical composition of polymeric materials under

The images for characterization were acquired by the stereoscopic microscopy Leica Wild M8 and a by a digital camera Olympus C-5060 Wide Zoom. The image analysis was carried out by the software SigmaScan Pro© Version 5.0.0 (Systat Software Inc., 2007), which provides a complete set of tools to analyse structure and dimension of an object's image.

Firstly, calibration allowed to convert image unit from pixel to millimetre (Figure 1). After calibration, the image quality for data elaboration has been enhanced, increasing the

an experimental plan was carried out to assess the feasibility of waste recycling.

• dry sieve analysis, to classify the size distribution of particles;

Experimental tests have been executed on several typologies of packing, as listed:

• bottles in poly(ethylene terephthalate) (PET), for syrup; • plastic bags and films of varying composition and thickness;

dangerous substances (Bauer, E.J. , 2009).

• waste materials characterization; • preliminary tests on waste processing;

• primary packaging:

• pharmaceutical waste:

**2.1 Methods for characterization** 

evaluated by statistical methods;

products under investigation:

**2. Experimental** 

1,000 μm;

investigation.

**2.1.1 Image analysis** 

pharmaceutical plant, considering the following phases:

• set up of size reduction (comminution) operations.

distinction between particles and background, by varying contrast, brightness and colour of the image (Figure 2). In the measurement process, the software automatically recognizes objects on the image (Figure 3) and computes geometric and morphologic parameters, accordingly to operator's choice.


Fig. 1. Calibration process to convert image unit from pixel to millimetre.

Fig. 2. Variation of contrast, brightness and colour of an image.

Fig. 3. Automatic recognition of objects on the image.

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 241

*Standard deviation*: shows how much variation or dispersion there is from the mean in the data set and it is measured in the same unit of the data. The standard deviation σ is directly derived from the variance (σ2, which unit is the square unit of the considered data), as its

<sup>i</sup> i=1 <sup>x</sup>

*Standard error*: returns an estimation of the standard deviation σx of the estimator, giving a valuation of its imprecision. If the estimator is the arithmetic mean of N independent measurements with the same statistical distribution, the standard error is given via the

<sup>σ</sup><sup>x</sup> se =

*Confidence interval*: refers to the range of values preceding or following a mean value where it is expected an unknown population parameter (e.g. the true mean) is located. The width of the confidence interval gives an indication about uncertainty of the unknown parameter. If independent samples are taken repeatedly from the same population, and a confidence interval calculated for each sample, then a certain percentage (confidence level) of the intervals will include the unknown parameter. The confidence level is the probability value (1 – α) associated with a confidence interval. For example, say α = 0.05, then the confidence

Let's be the true mean the considered unknown parameter; the confidence level is given

<sup>x</sup> conf <sup>σ</sup> x±A

where Aconf is area under the normal distribution curve that is equal to the chosen confidence level. In the case under investigation confidence levels of 95% and 99% have

The dry sieve analysis is a mechanical method to assess the particle size distribution. A set of sieves with wire mesh cloth is stacked in column, so that each lower sieve has smaller openings than the one above; at the base of the column there is a round pan. A representative weighed sample is poured into the top sieve. The column is typically placed in a mechanical shaker, that shakes the column for a fixed amount of time. After the shaking is complete the material on each sieve is weighed and divided by the total weight to gain the percentage retained on each sieve. In this study, certified high-precision sieves Giuliani in

N

<sup>σ</sup> <sup>=</sup> <sup>N</sup>

( ) <sup>N</sup>

x -x

(4)

<sup>N</sup> . (5)

(6)

square root:

equation:

by:

considered.

**2.1.2 Dry sieve analysis** 

stainless steel (ASTM series) were utilized.

where x is the arithmetic mean.

level is equal to 0.95, i.e. a 95% confidence level.

The following geometric and morphologic measurements were considered.

*Area*: reports the area in mm2 for the selected object.

*Compactness*: reports a numeric non-dimensional measurement of the shape of an object. It is defined as the perimeter squared, divided by the area:

$$\text{Compactness} = \frac{\text{perimeter}^2}{\text{area}} \tag{1}$$

The minimum Compactness of a perfectly measured and digitized circle is 4π (about 12.57). As an object tends toward the shape of a line, the Compactness tends towards infinity.

*Major Axis Length*: calculates major axis of the object (defined by the two most distant points on the object) and reports the length in mm of the axis.

*Minor Axis Length*: calculates minor axis of the object (defined by the two most distant points on the object that creates a line perpendicular to the major axis) and reports the length in mm of the axis.

*Perimeter*: returns the perimeter in mm of an object.

*Shape Factor*: measures the shape (circularity) of a measured object. This non-dimensional measure is defined as 4π times the object's area divided by the perimeter squared:

$$\text{Slope\\_factor} = \frac{4\pi \cdot area}{perimeter^2} \tag{2}$$

A perfect circle will have a Shape Factor of 1. A line's Shape Factor will approach zero.

*Feret Diameter*: describes the shape of an object. It gives the diameter of the equivalent circular object that has the same area as the current object. For each object, it calculates the theoretical diameter of the object if it were circular in shape. This measure is often compared with an object's major and minor axes lengths to create new shape parameters.

The results obtained from image analysis were evaluated by considering statistical parameters, as described in the following.

*Number of objects*: counts the numeric values in the considered set.

*Mean*: returns, as central tendency, the order of magnitude of the value for each considered measurement. The arithmetic mean *x* is calculated as the sum of all measurements divided by the number of observations in the data set:

$$\overline{\mathbf{x}} = \frac{1}{\mathbf{N}} \sum\_{i=1}^{N} \mathbf{x}\_i \tag{3}$$

where i x is the single measurement and N is the total number of measurements.

*Minimum*: returns the least value of the considered data set.

*Maximum*: returns the greatest value of the considered data set.

*Standard deviation*: shows how much variation or dispersion there is from the mean in the data set and it is measured in the same unit of the data. The standard deviation σ is directly derived from the variance (σ2, which unit is the square unit of the considered data), as its square root:

$$\sigma\_{\mathbf{x}} = \sqrt{\frac{\sum\_{i=1}^{N} (\mathbf{x}\_i \cdot \overline{\mathbf{x}})}{N}} \tag{4}$$

where x is the arithmetic mean.

240 Material Recycling – Trends and Perspectives

*Compactness*: reports a numeric non-dimensional measurement of the shape of an object. It is

<sup>2</sup> perimeter Compactness =

The minimum Compactness of a perfectly measured and digitized circle is 4π (about 12.57). As an object tends toward the shape of a line, the Compactness tends towards infinity.

*Major Axis Length*: calculates major axis of the object (defined by the two most distant points

*Minor Axis Length*: calculates minor axis of the object (defined by the two most distant points on the object that creates a line perpendicular to the major axis) and reports the length in

*Shape Factor*: measures the shape (circularity) of a measured object. This non-dimensional

<sup>4</sup> *area Shape factor*

*Feret Diameter*: describes the shape of an object. It gives the diameter of the equivalent circular object that has the same area as the current object. For each object, it calculates the theoretical diameter of the object if it were circular in shape. This measure is often compared

The results obtained from image analysis were evaluated by considering statistical

*Mean*: returns, as central tendency, the order of magnitude of the value for each considered measurement. The arithmetic mean *x* is calculated as the sum of all measurements divided

> N i i=1

1 x= x

where i x is the single measurement and N is the total number of measurements.

A perfect circle will have a Shape Factor of 1. A line's Shape Factor will approach zero.

with an object's major and minor axes lengths to create new shape parameters.

*Number of objects*: counts the numeric values in the considered set.

*Minimum*: returns the least value of the considered data set.

*Maximum*: returns the greatest value of the considered data set.

measure is defined as 4π times the object's area divided by the perimeter squared:

area

2

<sup>⋅</sup> <sup>=</sup> (2)

<sup>N</sup> (3)

*perimeter* π

(1)

The following geometric and morphologic measurements were considered.

*Area*: reports the area in mm2 for the selected object.

defined as the perimeter squared, divided by the area:

on the object) and reports the length in mm of the axis.

*Perimeter*: returns the perimeter in mm of an object.

parameters, as described in the following.

by the number of observations in the data set:

mm of the axis.

*Standard error*: returns an estimation of the standard deviation σx of the estimator, giving a valuation of its imprecision. If the estimator is the arithmetic mean of N independent measurements with the same statistical distribution, the standard error is given via the equation:

$$\text{base} = \frac{\sigma\_{\chi}}{\text{N}}.\tag{5}$$

*Confidence interval*: refers to the range of values preceding or following a mean value where it is expected an unknown population parameter (e.g. the true mean) is located. The width of the confidence interval gives an indication about uncertainty of the unknown parameter. If independent samples are taken repeatedly from the same population, and a confidence interval calculated for each sample, then a certain percentage (confidence level) of the intervals will include the unknown parameter. The confidence level is the probability value (1 – α) associated with a confidence interval. For example, say α = 0.05, then the confidence level is equal to 0.95, i.e. a 95% confidence level.

Let's be the true mean the considered unknown parameter; the confidence level is given by:

$$\overline{\mathbf{x}} \pm \mathbf{A}\_{\text{conf}} \left( \frac{\mathbf{o}\_{\mathbf{x}}}{\sqrt{\mathbf{N}}} \right) \tag{6}$$

where Aconf is area under the normal distribution curve that is equal to the chosen confidence level. In the case under investigation confidence levels of 95% and 99% have considered.

#### **2.1.2 Dry sieve analysis**

The dry sieve analysis is a mechanical method to assess the particle size distribution. A set of sieves with wire mesh cloth is stacked in column, so that each lower sieve has smaller openings than the one above; at the base of the column there is a round pan. A representative weighed sample is poured into the top sieve. The column is typically placed in a mechanical shaker, that shakes the column for a fixed amount of time. After the shaking is complete the material on each sieve is weighed and divided by the total weight to gain the percentage retained on each sieve. In this study, certified high-precision sieves Giuliani in stainless steel (ASTM series) were utilized.

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 243

Material HDPE Longitudinal dimension (cm) 11.0 Transversal dimension (cm) 5.5 average weight (g) 17.4 average powder content (mg) 40.0 average powder content (%) 0.05

The bottles in PET are utilized for syrup packaging. The analyzed samples are composed by waste bottles, collected at the end of the production line and manually emptied. The bottles may have labels and aluminium caps and may contain varying amount of residual syrup. A

> Material PET Longitudinal dimension (cm) 14.2 Transversal dimension (cm) 5.2 average weight (g) 23.2 average syrup content (mg) 19.0 average syrup content (%) 8.99

Plastic bags and films derive from the packaging of raw materials utilized in production processes. The analyzed samples are of varying composition and thickness, and contain residual powders, whose composition is in relation to the production cycle. Four different

The samples were analysed by FTIR spectrometry to identify the polymeric composition

As resulting from the comparison of acquired spectra with the reference one, all 4 types of materials are polyethylene (PE), in particular the recognized polymeric structure is low-

The residual powders were analysed by dry sieve analysis to identify size distribution, characterized by a mode of the distribution equal to 112 μm, while the top-size is lower than

The flexible multi-layered (plastic and aluminium) sachets containing granular medicine are wasted at the end of the production line because of incorrect filling. In this case, the sachets are collected and sent to disposal. The number of wasted sachet is 4·106 per year on average.

Table 1. Synthesis of the characteristics of HDPE bottles.

synthesis of PET bottles characteristics is reported in Table 2.

Table 2. Synthesis of the characteristics of PET bottles.

typologies of plastic bags and films were identified:

Table 3 reports a synthesis of the sachets characteristics.

• white and red bags, containing bicarbonate;

• bags, with printed character "A" in black; • bags, with printed character "A" in blue.

• thin-film;

(Figure 4).

1,000 µm.

density polyethylene (LDPE).

#### **2.1.3 Laser granulometry**

The laser granulometry analyses of the effect of diffracted light produced by a laser beam passing through a dispersion of particles. The angle of diffraction increases as particle size decreases. After mixing in distilled water (or alcohol), the representative sample is introduced in the measuring cell. The laser beam (wavelength = 632.8 nm; power = 5 mW) passes through the suspension and is deviated by particles accordingly to their particle size. The deviation is then analyzed by detectors. This method can measure particle sizes between 0.1 and 1,000 μm.

The laser granulometer utilized in this investigation was SYMPATEC HELOS/KA.

#### **2.1.4 FTIR spectroscopy**

The Fourier transform infrared (FTIR) spectroscopy utilizes the infrared region of the electromagnetic spectrum (between 0.8 and 1,000 μm wavelength) to recognize chemical composition of materials. In the case of plastic materials it allows to identify the structural polymer. The infrared spectrum (by transmittance or absorbance) of a sample is recorded by passing a beam of infrared light through the sample. A data-processing technique called Fourier transform converts raw data into the sample's spectrum. Then the sample's spectrum is compared to reference spectra. The samples were cleaned with water and mild detergent, rinsed with deionized water and then dried in oven with air convection at 450 °C for 24 hours.

The characteristics of the instrument utilized in this study for FTIR spectroscopy are:


### **2.2 Methods for waste processing**

Waste processing was carried out at laboratory scale to assess the feasibility of recycling. In particular, for the treatment of the different typologies of investigated pharmaceutical waste, comminution operations were evaluated. According to the composition of products (polymeric materials) cutting mills were employed, which apply shearing to reduce particle size. In this study a cutting mill Retsch – SM 2000 equipped with interchangeable sieves to control particle size in output product was utilized to carry out comminution tests.

#### **2.3 Materials**

The bottles in HDPE are utilized for suspension to be reconstituted. The analyzed samples are composed by waste bottles, collected at the end of the production line and manually emptied. The bottles are without labels and caps and may contain residual powder. A synthesis of HDPE bottles characteristics is reported in Table 1.


Table 1. Synthesis of the characteristics of HDPE bottles.

The bottles in PET are utilized for syrup packaging. The analyzed samples are composed by waste bottles, collected at the end of the production line and manually emptied. The bottles may have labels and aluminium caps and may contain varying amount of residual syrup. A synthesis of PET bottles characteristics is reported in Table 2.


Table 2. Synthesis of the characteristics of PET bottles.

Plastic bags and films derive from the packaging of raw materials utilized in production processes. The analyzed samples are of varying composition and thickness, and contain residual powders, whose composition is in relation to the production cycle. Four different typologies of plastic bags and films were identified:


242 Material Recycling – Trends and Perspectives

The laser granulometry analyses of the effect of diffracted light produced by a laser beam passing through a dispersion of particles. The angle of diffraction increases as particle size decreases. After mixing in distilled water (or alcohol), the representative sample is introduced in the measuring cell. The laser beam (wavelength = 632.8 nm; power = 5 mW) passes through the suspension and is deviated by particles accordingly to their particle size. The deviation is then analyzed by detectors. This method can measure particle sizes

The Fourier transform infrared (FTIR) spectroscopy utilizes the infrared region of the electromagnetic spectrum (between 0.8 and 1,000 μm wavelength) to recognize chemical composition of materials. In the case of plastic materials it allows to identify the structural polymer. The infrared spectrum (by transmittance or absorbance) of a sample is recorded by passing a beam of infrared light through the sample. A data-processing technique called Fourier transform converts raw data into the sample's spectrum. Then the sample's spectrum is compared to reference spectra. The samples were cleaned with water and mild detergent, rinsed with deionized water and then dried in oven with air convection at 450 °C

The laser granulometer utilized in this investigation was SYMPATEC HELOS/KA.

The characteristics of the instrument utilized in this study for FTIR spectroscopy are:

Waste processing was carried out at laboratory scale to assess the feasibility of recycling. In particular, for the treatment of the different typologies of investigated pharmaceutical waste, comminution operations were evaluated. According to the composition of products (polymeric materials) cutting mills were employed, which apply shearing to reduce particle size. In this study a cutting mill Retsch – SM 2000 equipped with interchangeable sieves to control particle size in output product was utilized to carry out comminution

The bottles in HDPE are utilized for suspension to be reconstituted. The analyzed samples are composed by waste bottles, collected at the end of the production line and manually emptied. The bottles are without labels and caps and may contain residual powder. A

**2.1.3 Laser granulometry** 

between 0.1 and 1,000 μm.

**2.1.4 FTIR spectroscopy** 

• FTIR Perkin-Elmer SpectrumOne;

• wavenumber range: 4000-630 cm-1;

**2.2 Methods for waste processing** 

• equipped with HATR, crystal ZnSe, 45°, (pressure 90) ;

synthesis of HDPE bottles characteristics is reported in Table 1.

for 24 hours.

tests.

**2.3 Materials** 

• resolution: 4 cm-1; • number of scanning: 4.


The samples were analysed by FTIR spectrometry to identify the polymeric composition (Figure 4).

As resulting from the comparison of acquired spectra with the reference one, all 4 types of materials are polyethylene (PE), in particular the recognized polymeric structure is lowdensity polyethylene (LDPE).

The residual powders were analysed by dry sieve analysis to identify size distribution, characterized by a mode of the distribution equal to 112 μm, while the top-size is lower than 1,000 µm.

The flexible multi-layered (plastic and aluminium) sachets containing granular medicine are wasted at the end of the production line because of incorrect filling. In this case, the sachets are collected and sent to disposal. The number of wasted sachet is 4·106 per year on average. Table 3 reports a synthesis of the sachets characteristics.

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 245



Fig. 5. Size distribution of granular medicine contained in sachets by laser granulometry.

The technical details of the industrial shredder are shown in the Table 4.

Model F615 Engine power 11 kW n. shafts 2

n. blades of 30 mm 19

different operational configurations:

• with a 20 mm mesh grid.

Producer Satrind S.p.A.

Speed shafts 19/10-15/8 rpm

comminuted products. The comminution chamber of the mill is shown in Figure 6.

• without the grids for the control of the size of the comminuted products;

Table 4. Technical characteristics of industrial shredder installed in the investigated plant.

On the two shafts of the shredder 19 blades are fixed that, thanks mainly to the application of cut stresses, are able to break the waste materials (Figure 6). Some of the material is broken by tear action due to the rotation of the blades. In the preliminary lab tests, the application of cut stresses have been obtained by mean of a blade mill RETSCH - SM 2000, that can be equipped or not with different grids that allow to control the size of the

The preliminary laboratory tests have been conducted in dry conditions adopting two


• primary packaging:

• pharmaceutical waste:

Fig. 4. FTIR spectra of plastic bags and films (y-axis: transmission %; x-axis: wavenumber cm-1) : white and red bags, containing bicarbonate (above left), thin-film (above right), bags, with printed character "A" in black (below left), bags, with printed character "A" in blue (below right).


Table 3. Synthesis of the characteristics of flexible multi-layered (plastic and aluminium) sachets.

The granular medicine contained in sachets was analysed by dry sieve analysis and by laser granulometer to identify size distribution. Size distribution was analyzed by dry sieve analysis and laser granulometry (Figure 5), showing different mode and top-size. In particular, laser granulometry shows lower value of both (mode: 40 μm, top size: 100 μm) than dry sieve analysis (mode: 280 μm, top size: 1000 μm). This is probably due to the breakup of aggregated granules during mixing in water.

#### **2.4 Preliminary tests**

For the recovery of the waste materials, in order to evaluate the possibility of adopting an industrial shredder installed in the production plant under investigation, preliminary comminution tests have been carried out on the following waste typologies:

• primary packaging:

244 Material Recycling – Trends and Perspectives

729,32

729,39

Fig. 4. FTIR spectra of plastic bags and films (y-axis: transmission %; x-axis: wavenumber cm-1) : white and red bags, containing bicarbonate (above left), thin-film (above right), bags, with printed character "A" in black (below left), bags, with printed character "A" in blue

Material plastic and aluminium

Table 3. Synthesis of the characteristics of flexible multi-layered (plastic and aluminium)

The granular medicine contained in sachets was analysed by dry sieve analysis and by laser granulometer to identify size distribution. Size distribution was analyzed by dry sieve analysis and laser granulometry (Figure 5), showing different mode and top-size. In particular, laser granulometry shows lower value of both (mode: 40 μm, top size: 100 μm) than dry sieve analysis (mode: 280 μm, top size: 1000 μm). This is probably due to the break-

For the recovery of the waste materials, in order to evaluate the possibility of adopting an industrial shredder installed in the production plant under investigation, preliminary

comminution tests have been carried out on the following waste typologies:

Longitudinal dimension (cm) 11.8 Transversal dimension (cm) 2.2 average weight of sachet(g) 7.4 average powder content (mg) 3.2 average powder content (%) 0.46

%T

%T

2914,40 2846,03

2914,72 2846,79

4000, <sup>300</sup> <sup>200</sup> <sup>150</sup> <sup>100</sup> 630, 85,

cm-

4000,0 3000 2000 1500 1000 630,0

cm-1

1461,99

1462,49

1367,73

729,06

729,21

4000,0 3000 2000 1500 1000 630,0

1462,25

1462,15

cm-1

4000,0 3000 2000 1500 1000 630,0

cm-1

up of aggregated granules during mixing in water.

(below right).

sachets.

**2.4 Preliminary tests** 

%T

%T 2914,46

2846,31

2914,44 2846,22

	- flexible multi-layered (plastic and aluminium) sachets containing granular medicine.

Fig. 5. Size distribution of granular medicine contained in sachets by laser granulometry.


The technical details of the industrial shredder are shown in the Table 4.

Table 4. Technical characteristics of industrial shredder installed in the investigated plant.

On the two shafts of the shredder 19 blades are fixed that, thanks mainly to the application of cut stresses, are able to break the waste materials (Figure 6). Some of the material is broken by tear action due to the rotation of the blades. In the preliminary lab tests, the application of cut stresses have been obtained by mean of a blade mill RETSCH - SM 2000, that can be equipped or not with different grids that allow to control the size of the comminuted products. The comminution chamber of the mill is shown in Figure 6.

The preliminary laboratory tests have been conducted in dry conditions adopting two different operational configurations:


Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 247

Fig. 7. Comminuted bottles in HDPE (left) and PET (right) obtained in the preliminary tests

The preliminary comminuted tests have been carried out on samples of plastic bags containing bicarbonate and on samples of films. Both sample typologies are made of LDPE. The plastic bags and films have been cut in samples of 50×50 mm and 100×100 mm in order to reach dimensions suitable for the laboratory blade mill. The tests carried out without the adoption of the control grids did not produce useful results, as no breakage were observed in the samples of 50×50 mm, and clogging and consequent stoppage of the mill for the samples 100×100 mm took place. On the contrary, in the tests carried out with the adoption of a 20 mm mesh control grid it was possible to break the plastic bags and films, both the 50×50 mm and 100×100 mm samples. The comminuted products of 100×100 mm samples of bags and films are shown in Figure 8. When submitted to sieving classification, the comminuted products presented average size generally above 1.0 mm and, therefore, higher than the higher average size of the powder medicine contained in

Fig. 8. Comminuted 100×100 mm samples of bags (left) and films (right) obtained in the

preliminary tests with the adoption of a 20 mm mesh control grid.

with the adoption of a 20 mm mesh control grid.

the bags and films.

• *Plastic bags and films of varying composition and thickness* 

Fig. 6. Industrial shredder blades (left) and comminution chamber of the blade mill adopted in the preliminary tests (right).

#### **2.4.1 Results of the preliminary laboratory tests**

The preliminary lab tests have shown the effectiveness of the application of cut stresses to break the considered typologies of pharmaceutical waste materials. Moreover, the comminuted products obtained in the tests are characterised by an average lower size that is above the higher average size of the powder and granular medicine contained in the waste sachet (1.0 mm). The results obtained in the preliminary tests are reported for each considered waste typologies in the following.

• B*ottles in high density polyethylene (HDPE), for suspension to be reconstituted*

The bottles have been divided in two parts in order to reach dimensions suitable for the laboratory blade mill.

The tests carried out without the adoption of the control grids did not produce useful results, as no breakage were observed in the bottles collected in the output.

On the contrary, in the tests carried out with the adoption of a 20 mm mesh control grid it was possible to break the bottles in HDPE and reach comminuted products mainly belonging to the size class +1.0 mm. The comminuted products are shown in Figure 7.

• *Bottles in poly(ethylene terephthalate) (PET), for syrup* 

The bottles have been divided in two parts in order to reach dimensions suitable for the laboratory blade mill. The bottles have been divided in two parts in order to reach dimensions suitable for the laboratory blade mill. The tap and aluminium ring have been kept in the sample. The bottles submitted to the tests did not contain syrup. The tests carried out without the adoption of the control grids did not produce useful results, as no breakage were observed in the bottles collected in the output. On the contrary, in the tests carried out with the adoption of a 20 mm mesh control grid it was possible to break the bottles in PET and reach comminuted products mainly belonging to the size class +1.0 mm. The comminuted products are shown in Figure 7.

Fig. 7. Comminuted bottles in HDPE (left) and PET (right) obtained in the preliminary tests with the adoption of a 20 mm mesh control grid.

#### • *Plastic bags and films of varying composition and thickness*

246 Material Recycling – Trends and Perspectives

Fig. 6. Industrial shredder blades (left) and comminution chamber of the blade mill adopted

The preliminary lab tests have shown the effectiveness of the application of cut stresses to break the considered typologies of pharmaceutical waste materials. Moreover, the comminuted products obtained in the tests are characterised by an average lower size that is above the higher average size of the powder and granular medicine contained in the waste sachet (1.0 mm). The results obtained in the preliminary tests are reported for each

The bottles have been divided in two parts in order to reach dimensions suitable for the

The tests carried out without the adoption of the control grids did not produce useful

On the contrary, in the tests carried out with the adoption of a 20 mm mesh control grid it was possible to break the bottles in HDPE and reach comminuted products mainly belonging to the size class +1.0 mm. The comminuted products are shown in Figure 7.

The bottles have been divided in two parts in order to reach dimensions suitable for the laboratory blade mill. The bottles have been divided in two parts in order to reach dimensions suitable for the laboratory blade mill. The tap and aluminium ring have been kept in the sample. The bottles submitted to the tests did not contain syrup. The tests carried out without the adoption of the control grids did not produce useful results, as no breakage were observed in the bottles collected in the output. On the contrary, in the tests carried out with the adoption of a 20 mm mesh control grid it was possible to break the bottles in PET and reach comminuted products mainly belonging to the size class +1.0 mm. The

• B*ottles in high density polyethylene (HDPE), for suspension to be reconstituted*

results, as no breakage were observed in the bottles collected in the output.

in the preliminary tests (right).

laboratory blade mill.

**2.4.1 Results of the preliminary laboratory tests** 

considered waste typologies in the following.

• *Bottles in poly(ethylene terephthalate) (PET), for syrup* 

comminuted products are shown in Figure 7.

The preliminary comminuted tests have been carried out on samples of plastic bags containing bicarbonate and on samples of films. Both sample typologies are made of LDPE.

The plastic bags and films have been cut in samples of 50×50 mm and 100×100 mm in order to reach dimensions suitable for the laboratory blade mill. The tests carried out without the adoption of the control grids did not produce useful results, as no breakage were observed in the samples of 50×50 mm, and clogging and consequent stoppage of the mill for the samples 100×100 mm took place. On the contrary, in the tests carried out with the adoption of a 20 mm mesh control grid it was possible to break the plastic bags and films, both the 50×50 mm and 100×100 mm samples. The comminuted products of 100×100 mm samples of bags and films are shown in Figure 8. When submitted to sieving classification, the comminuted products presented average size generally above 1.0 mm and, therefore, higher than the higher average size of the powder medicine contained in the bags and films.

Fig. 8. Comminuted 100×100 mm samples of bags (left) and films (right) obtained in the preliminary tests with the adoption of a 20 mm mesh control grid.

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 249

Fig. 11. Comminuted flexible multi-layered sachets containing granular medicine, belonging to the size class -0.5 mm, obtained in the preliminary tests without control grid (left) and

On the basis of the results of the preliminary tests, the comminution processes in laboratory scale have been set up. Notably, the tests have been carried out adopting the blade mill

Wet drying has been realised feeding the mill with the waste materials together with little quantities of water. In such a way, the operational conditions that could be achieved with the shredder installed in the considered industrial plant have been simulated. For the Flexible multi-layered (plastic and aluminium) sachets, tests have been conducted with the blade mill and with a mini-shredder, in order to evaluate the possibility of recovering the granular medicine they contain. The comminuted products have been analysed by mean of:

The comminution processes are described in the following paragraphs, for each considered

The HDPE bottles have been cut in their longitudinal axes before feeding them to the blade

In the dry comminution tests, samples made of 5 bottles in HDPE have been adopted. The products of the dry and wet comminution tests have been submitted to dry sieving and image analysis. The sieving tests have been conducted adopting sieves of ASTM series with 2.0 and 1.0 mm mesh. The results of the sieving tests are reported in Figure 12 in terms of

• *Bottles in high density polyethylene (HDPE), for suspension to be reconstituted* 

cumulative passing for dry and wet comminution tests.

with 20 mm mesh control grid (right).

**2.5 Waste processing (comminution) tests** 

• dry milling, with 2 cm mesh control grid; • wet milling, with 2 cm mesh control grid.

• dry sieving;

waste typology.

mill.

• laser granulometry; • imagine analysis.

Retsch - SM 2000 under two operational conditions:

#### • *Flexible multi-layered (plastic and aluminium) sachets containing granular medicine*

Preliminary tests were conducted on flexible multi-layered sachets containing granular medicine. The comminution tests resulted effective both without and with the adoption of the 20 mm mesh control grid. Notably, due to the lower resident time, the milling operations conducted without the control grid produced particles belonging to size classes greater than 1.0, i.e. greater than the maximum size of the granulate medicine contained in the sachet. Figure 9 shows the comminuted products classified in the size class +1.0 mm, while Figure 10 and Figure 11 show the comminuted products classified in the size classes obtained -1.0 +0.5 mm and -0.5 mm.

Fig. 9. Comminuted flexible multi-layered sachets containing granular medicine, belonging to the size class +1.0 mm, obtained in the preliminary tests without control grid (left) and with 20 mm mesh control grid (right).

Fig. 10. Comminuted flexible multi-layered sachets containing granular medicine, belonging to the size class -1.0 +0.5 mm, obtained in the preliminary tests without control grid (left) and with 20 mm mesh control grid (right).

Fig. 11. Comminuted flexible multi-layered sachets containing granular medicine, belonging to the size class -0.5 mm, obtained in the preliminary tests without control grid (left) and with 20 mm mesh control grid (right).

### **2.5 Waste processing (comminution) tests**

On the basis of the results of the preliminary tests, the comminution processes in laboratory scale have been set up. Notably, the tests have been carried out adopting the blade mill Retsch - SM 2000 under two operational conditions:


Wet drying has been realised feeding the mill with the waste materials together with little quantities of water. In such a way, the operational conditions that could be achieved with the shredder installed in the considered industrial plant have been simulated. For the Flexible multi-layered (plastic and aluminium) sachets, tests have been conducted with the blade mill and with a mini-shredder, in order to evaluate the possibility of recovering the granular medicine they contain. The comminuted products have been analysed by mean of:

• dry sieving;

248 Material Recycling – Trends and Perspectives

Preliminary tests were conducted on flexible multi-layered sachets containing granular medicine. The comminution tests resulted effective both without and with the adoption of the 20 mm mesh control grid. Notably, due to the lower resident time, the milling operations conducted without the control grid produced particles belonging to size classes greater than 1.0, i.e. greater than the maximum size of the granulate medicine contained in the sachet. Figure 9 shows the comminuted products classified in the size class +1.0 mm, while Figure 10 and Figure 11 show the comminuted products classified in the size classes obtained -1.0

Fig. 9. Comminuted flexible multi-layered sachets containing granular medicine, belonging to the size class +1.0 mm, obtained in the preliminary tests without control grid (left) and

Fig. 10. Comminuted flexible multi-layered sachets containing granular medicine, belonging to the size class -1.0 +0.5 mm, obtained in the preliminary tests without control grid (left)

• *Flexible multi-layered (plastic and aluminium) sachets containing granular medicine* 

+0.5 mm and -0.5 mm.

with 20 mm mesh control grid (right).

and with 20 mm mesh control grid (right).


The comminution processes are described in the following paragraphs, for each considered waste typology.

• *Bottles in high density polyethylene (HDPE), for suspension to be reconstituted* 

The HDPE bottles have been cut in their longitudinal axes before feeding them to the blade mill.

In the dry comminution tests, samples made of 5 bottles in HDPE have been adopted. The products of the dry and wet comminution tests have been submitted to dry sieving and image analysis. The sieving tests have been conducted adopting sieves of ASTM series with 2.0 and 1.0 mm mesh. The results of the sieving tests are reported in Figure 12 in terms of cumulative passing for dry and wet comminution tests.

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 251

*+2.0 mm -2.0 mm +1.0 mm -1.0 mm* 

*+2.0 mm -2.0 mm +1.0 mm -1.0 mm* 

The high values of the parameter *Compactness*, measured in the products of both dry and wet comminution products, are in relation with the irregular morphology of particles,

The statistic parameters, notably the standard deviation, show a high variability in the analysed particles, with standard error and confidence intervals substantially constant for

**# Obj** 120 120 120 120 120 120 120 **Mean** 205.066 188.244 24.942 13.659 173.927 0.124 15.124 **Min** 7.272 34.974 6.584 2.208 27.283 0.009 3.043 **Max** 961.603 1437.503 73.747 24.068 753.578 0.359 34.991 **Std Dev** 152.176 232.241 10.375 5.290 129.450 0.077 5.712 **Std Err** 13.892 21.201 0.947 0.483 11.817 0.007 0.521 **95% Conf** 37.879 57.808 2.583 1.317 32.222 0.019 1.422 **99% Conf** 49.781 75.973 3.394 1.730 42.347 0.025 1.869

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

Fig. 14. Bottles in HDPE, images of the products of dry comminution tests.

Fig. 15. Bottles in HDPE, images of the products of wet comminution tests.

The values of the parameter Shape Factor describe a shape of elongated particles.

reasonably due to the cut stresses applied by the blades of the mill.

Table 5. Bottles in HDPE, dry comminution, size class: +2.0 mm.

both dry and wet comminution products.

Comparing the results of sieving tests (Figure 13), the dry and wet comminution tests do not show substantial differences in the size distribution of their products.

Fig. 12. Bottles in HDPE, 20 mm grid, cumulative passing, dry (left) and wet (right) comminution.

After the classification of particles in the size classes +2 mm, -2 mm +1 mm, and -1 mm obtained by sieving, image analysis has been conducted on the products of dry and wet comminution tests.

The results of image analysis for the bottles in HDPE are given in Tables 5-10.

Examples of images of the dry and wet comminution products are shown in Figure 14 and Figure 15 respectively.

Comparing the results of the image analysis for the considered size classes, no major differences can be observed in the particles size of the products obtained in the dry and wet comminution tests in terms of the values of the parameters *Area, Major Axis Length, Minor Axis Length and Feret Diameter*.

Comparing the results of sieving tests (Figure 13), the dry and wet comminution tests do not

**0**

**0,1 1,0 10,0 100,0 particle size (mm)**

**wet comminution dry comminution**

**25**

**50**

**cumulative passing (%)**

**-20 +2 +2 -1 -1 particle size (mm)**

Fig. 13. Bottles in HDPE, comparison of the products of dry and wet comminution tests in

After the classification of particles in the size classes +2 mm, -2 mm +1 mm, and -1 mm obtained by sieving, image analysis has been conducted on the products of dry and wet

Examples of images of the dry and wet comminution products are shown in Figure 14 and

Comparing the results of the image analysis for the considered size classes, no major differences can be observed in the particles size of the products obtained in the dry and wet comminution tests in terms of the values of the parameters *Area, Major Axis Length, Minor* 

The results of image analysis for the bottles in HDPE are given in Tables 5-10.

Fig. 12. Bottles in HDPE, 20 mm grid, cumulative passing, dry (left) and wet (right)

**75**

**100**

show substantial differences in the size distribution of their products.

**0,1 1,0 10,0 100,0 particle size (mm)**

**0**

comminution.

**0**

terms of size distribution.

comminution tests.

Figure 15 respectively.

*Axis Length and Feret Diameter*.

**25**

**50**

**weight (%)**

**75**

**100**

**25**

**50**

**cumulative passing (%)**

**75**

**100**

*+2.0 mm -2.0 mm +1.0 mm -1.0 mm* 

Fig. 14. Bottles in HDPE, images of the products of dry comminution tests.

*+2.0 mm -2.0 mm +1.0 mm -1.0 mm* 

Fig. 15. Bottles in HDPE, images of the products of wet comminution tests.

The high values of the parameter *Compactness*, measured in the products of both dry and wet comminution products, are in relation with the irregular morphology of particles, reasonably due to the cut stresses applied by the blades of the mill.

The values of the parameter Shape Factor describe a shape of elongated particles.

The statistic parameters, notably the standard deviation, show a high variability in the analysed particles, with standard error and confidence intervals substantially constant for both dry and wet comminution products.


Table 5. Bottles in HDPE, dry comminution, size class: +2.0 mm.

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 253

**# Obj** 29 29 29 29 29 29 29 **Mean** 5.231 91.432 4.927 1.874 20.587 0.176 2.517 **Min** 0.885 26.783 1.890 0.700 8.621 0.051 1.062 **Max** 9.565 245.852 10.922 3.359 34.566 0.469 3.490 **Std Dev** 2.190 45.358 1.892 0.656 6.504 0.100 0.580 **Std Err** 0.407 8.423 0.351 0.122 1.208 0.018 0.108 **95% Conf** 0.545 11.290 0.471 0.163 1.619 0.025 0.144 **99% Conf** 0.717 14.838 0.619 0.215 2.128 0.033 0.190

**# Obj** 61 61 61 61 61 61 61 **Mean** 1.279 71.463 2.384 0.911 8.827 0.223 1.178 **Min** 0.115 20.377 0.529 0.255 1.529 0.077 0.382 **Max** 7.051 164.213 7.085 3.252 28.419 0.617 2.996 **Std Dev** 1.151 34.111 1.293 0.481 4.833 0.115 0.495 **Std Err** 0.147 4.367 0.166 0.062 0.619 0.015 0.063 **95% Conf** 0.287 8.491 0.322 0.120 1.203 0.029 0.123 **99% Conf** 0.377 11.159 0.423 0.157 1.581 0.038 0.162

> **0,1 1,0 10,0 100,0 particle size (mm)**

products of comminution could not be easily extracted from the mill due to the presence of the syrup acting as a bonding agent for the PET particles and the mill surface. The dry

Fig. 16. Bottles in PET, 20 mm grid, cumulative passing, dry comminution.

Table 9. Bottles in HDPE, wet comminution, size class: -2 +1 mm.

Table 10. Bottles in HDPE, wet comminution, size class: -1 mm.

**0**

**25**

**50**

**cumulative passing (%)**

**75**

**100**

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 


Table 6. Bottles in HDPE, dry comminution, size class: -2.0 +1.0 mm.


Table 7. Bottles in HDPE, dry comminution, size class: -1.0 mm.


Table 8. Bottles in HDPE, wet comminution, size class: +1 mm.

• *Bottles in poly(ethylene terephthalate) (PET), for syrup* 

The PET bottles have been fed to the blade mill without any pre-treatment, therefore including the aluminium cap and relative ring, and in some cases also the paper labels. The comminuted tests have been carried out only in dry conditions, as in the wet tests the


Table 9. Bottles in HDPE, wet comminution, size class: -2 +1 mm.

252 Material Recycling – Trends and Perspectives

**# Obj** 42 42 42 42 42 42 42 **Mean** 5.917 107.792 5.397 2.067 22.963 0.194 2.649 **Min** 0.909 22.001 2.209 0.863 9.138 0.018 1.076 **Max** 15.461 684.613 11.824 3.209 92.040 0.571 4.437 **Std Dev** 3.175 110.433 2.439 0.589 14.100 0.122 0.727 **Std Err** 0.490 17.040 0.376 0.091 2.176 0.019 0.112 **95% Conf** 0.790 27.488 0.607 0.147 3.510 0.030 0.181 **99% Conf** 1.039 36.126 0.798 0.193 4.612 0.040 0.238

**# Obj** 48 48 48 48 48 48 48 **Mean** 1.040 67.968 2.205 0.768 7.582 0.263 1.023 **Min** 0.011 19.554 0.185 0.054 0.514 0.055 0.118 **Max** 3.614 227.840 6.093 2.334 21.682 0.643 2.145 **Std Dev** 0.930 45.895 1.494 0.433 5.192 0.148 0.532 **Std Err** 0.134 6.624 0.216 0.062 0.749 0.021 0.077 **95% Conf** 0.232 11.424 0.372 0.108 1.292 0.037 0.132 **99% Conf** 0.304 15.014 0.489 0.142 1.698 0.048 0.174

**# Obj** 70 70 70 70 70 70 70 **Mean** 178.616 286.454 25.949 13.569 203.690 0.084 14.500 **Min** 22.718 38.559 10.575 3.509 42.665 0.009 5.378 **Max** 349.484 1430.789 41.267 22.467 558.069 0.326 21.094 **Std Dev** 94.828 263.140 7.478 4.529 112.930 0.066 4.175 **Std Err** 11.334 31.451 0.894 0.541 13.498 0.008 0.499 **95% Conf** 23.604 65.500 1.861 1.127 28.110 0.016 1.039 **99% Conf** 31.021 86.081 2.446 1.482 36.943 0.022 1.366

The PET bottles have been fed to the blade mill without any pre-treatment, therefore including the aluminium cap and relative ring, and in some cases also the paper labels. The comminuted tests have been carried out only in dry conditions, as in the wet tests the

Table 6. Bottles in HDPE, dry comminution, size class: -2.0 +1.0 mm.

Table 7. Bottles in HDPE, dry comminution, size class: -1.0 mm.

Table 8. Bottles in HDPE, wet comminution, size class: +1 mm.

• *Bottles in poly(ethylene terephthalate) (PET), for syrup* 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 


Table 10. Bottles in HDPE, wet comminution, size class: -1 mm.

Fig. 16. Bottles in PET, 20 mm grid, cumulative passing, dry comminution.

products of comminution could not be easily extracted from the mill due to the presence of the syrup acting as a bonding agent for the PET particles and the mill surface. The dry

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 255

**# Obj** 183 183 183 183 183 183 183 **Mean** 164.865 44.458 21.181 11.656 77.378 0.334 13.151 **Min** 0.563 16.702 1.171 0.805 4.024 0.083 0.847 **Max** 571.600 152.309 50.237 27.126 264.501 0.752 26.977 **Std Dev** 140.469 20.766 9.826 5.912 42.869 0.132 6.097 **Std Err** 10.384 1.535 0.726 0.437 3.169 0.010 0.451 **95% Conf** 34.965 5.169 2.446 1.472 10.671 0.033 1.518 **99% Conf** 45.952 6.793 3.214 1.934 14.024 0.043 1.995

**# Obj** 46 46 46 46 46 46 46 **Mean** 5.681 47.475 4.676 2.072 15.530 0.327 2.587 **Min** 0.463 19.162 1.763 0.560 4.587 0.105 0.768 **Max** 17.147 119.185 11.921 3.325 38.087 0.656 4.672 **Std Dev** 3.379 24.258 2.045 0.559 7.238 0.142 0.744 **Std Err** 0.498 3.577 0.302 0.082 1.067 0.021 0.110 **95% Conf** 0.841 6.038 0.509 0.139 1.802 0.035 0.185 **99% Conf** 1.106 7.936 0.669 0.183 2.368 0.046 0.243

**# Obj** 8 8 8 8 8 8 8 **Mean** 4.690 72.620 3.232 1.592 18.006 0.320 2.002 **Min** 0.111 28.067 0.595 0.334 1.764 0.038 0.376 **Max** 22.233 330.335 7.219 4.877 85.700 0.448 5.321 **Std Dev** 7.236 104.285 2.024 1.471 27.651 0.127 1.498 **Std Err** 2.558 36.870 0.716 0.520 9.776 0.045 0.530 **95% Conf** 1.801 25.958 0.504 0.366 6.883 0.032 0.373 **99% Conf** 2.367 34.115 0.662 0.481 9.046 0.042 0.490

The composition of the samples that contain the 4 typologies of plastic bags and films used

Table 11. Bottles in PET, dry comminution, size class: +2 mm.

Table 12. Bottles in PET, dry comminution, size class: -2 +1 mm.

Table 13. Bottles in PET, dry comminution, size class: -1 mm +38 μm.

• *Plastic bags and films of varying composition and thickness* 

in the dry and wet comminution tests are reported in Table 14.

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

comminution tests have been carried out on samples composed of 5 PET bottles. The products of the dry comminution tests have been submitted to dry sieving, laser granulometry and image analysis. The sieving tests have been conducted adopting sieves of ASTM series with 2.0, 1.0 mm and 38 μm mesh. Results of sieving tests and of laser granulometry analysis are reported in Figure 16 and Figure 17, respectively, both as cumulative passing for the dry comminution tests. The size class -38 μm has not been analyzed due to the presence of paper fibres of the labels including fine plastic particles.

After the classification in the particle size classes +2 mm, -2 mm +1 mm, and -1 mm +38 µm obtained by sieving, image analysis have been conducted on the products of dry comminution tests. The results of image analysis for the bottles in PET are given in Tables 11-13. Examples of images of the dry comminution products are shown in Figure 18.

Fig. 17. Bottles in PET, 20 mm grid, size distribution, dry comminution, size class +2.0 – 1.0 mm (left) and -1 mm +38 μm (right), laser granulometry.

Fig. 18. Bottles in PET, images of the products of dry comminution tests.

The high values of the parameter *Compactness*, measured in the products of both dry comminution products, are in relation with the irregular morphology of particles, reasonably due to the cut stresses applied by the blades of the mill. The values of the parameter Shape Factor describe a shape of elongated particles. The statistic parameters, notably the standard deviation, show a high variability in the analysed particles, in particular for the higher size class (+2 mm), while the intermediate size class (-2 +1 mm) presents more homogeneous values of the morphologic and dimensional parameters.


Table 11. Bottles in PET, dry comminution, size class: +2 mm.

254 Material Recycling – Trends and Perspectives

comminution tests have been carried out on samples composed of 5 PET bottles. The products of the dry comminution tests have been submitted to dry sieving, laser granulometry and image analysis. The sieving tests have been conducted adopting sieves of ASTM series with 2.0, 1.0 mm and 38 μm mesh. Results of sieving tests and of laser granulometry analysis are reported in Figure 16 and Figure 17, respectively, both as cumulative passing for the dry comminution tests. The size class -38 μm has not been analyzed due to the presence of paper fibres of the labels including fine plastic particles.

After the classification in the particle size classes +2 mm, -2 mm +1 mm, and -1 mm +38 µm obtained by sieving, image analysis have been conducted on the products of dry comminution tests. The results of image analysis for the bottles in PET are given in Tables

> 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

*+2.0 mm -2.0 mm +1.0 mm -1.0 mm +38.0 μm* 

The high values of the parameter *Compactness*, measured in the products of both dry comminution products, are in relation with the irregular morphology of particles, reasonably due to the cut stresses applied by the blades of the mill. The values of the parameter Shape Factor describe a shape of elongated particles. The statistic parameters, notably the standard deviation, show a high variability in the analysed particles, in particular for the higher size class (+2 mm), while the intermediate size class (-2 +1 mm)

presents more homogeneous values of the morphologic and dimensional parameters.

Fig. 18. Bottles in PET, images of the products of dry comminution tests.

0.05 0.1 0.5 1 5 10 50 100 500 1000 particle size / µm

density distribution q3\*(x)

Fig. 17. Bottles in PET, 20 mm grid, size distribution, dry comminution, size class +2.0 – 1.0

11-13. Examples of images of the dry comminution products are shown in Figure 18.

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

> 0.05 0.1 0.5 1 5 10 50 100 500 particle size / µm

mm (left) and -1 mm +38 μm (right), laser granulometry.

density distribution q3\*(x)


Table 12. Bottles in PET, dry comminution, size class: -2 +1 mm.


Table 13. Bottles in PET, dry comminution, size class: -1 mm +38 μm.

• *Plastic bags and films of varying composition and thickness* 

The composition of the samples that contain the 4 typologies of plastic bags and films used in the dry and wet comminution tests are reported in Table 14.

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 257

**wet comminution dry comminution**

**-20 +2 +2 -1 -1 particle size (mm)**

> 0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00

> > 0.05 0.1 0.5 1 5 10 50 100 500 1000 particle size / µm

density distribution q3\*(x)

Fig. 21. Plastic bags and films, 20 mm grid, size distribution, size class – 1.0 mm, dry

Comparing the results obtained in the laser granulometry analysis, the dry and wet comminution tests do not show substantial differences in the size distribution of their

After the division in the particle size classes in +2 mm, -2 mm +1 mm, and -1 mm obtained by sieving, image analysis have been conducted on the products of dry and wet comminution tests. The results of image analysis for the plastic bags and films are given in Tables 15-20. Examples of images taken of the dry and wet comminution products are

The results of image analysis are reported in the following for all the considered size classes. Comparing the results of the image analysis for the considered size classes, the difference between dry and wet comminution tests can be observed in the dimensions of the collected particles, measured by the values of *Area, Major Axis Length, Minor Axis Length e Feret* 

The high values of the parameter *Compactness*, measured in the products of both dry and wet comminution products, are in relation with the irregular morphology of particles, reasonably

due to the cut stresses applied by the blades of the mill to very thin material (LDPE).

Fig. 20. Plastic bags and films, comparison of the products of dry and wet comminution tests

**0**

0.05 0.1 0.5 1 5 10 50 100 500 1000

shown in Figure 22 and Figure 23 respectively.

particle size / µm

comminution (left) and wet comminution (right), laser granulometry.

*Diameter*: the analysed particles generally belong to smaller size classes.

**25**

**50**

**weight (%)**

in terms of size distribution.

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

products.

density distribution q3\*(x)

**75**

**100**


Table 14. Composition of the samples of plastic bags and films used in the dry and wet comminution tests.

The plastic bags and films have been cut in samples of 50×50 mm in order to reach dimensions suitable for the laboratory blade mill. Moreover, the samples maintained their content of bulk powder.

The products of the dry and wet comminution tests have been submitted to dry sieving, laser granulometry and image analysis.

The sieving tests have been conducted adopting sieves of ASTM series with 2.0 and 1.0 mm mesh. The results of the sieving tests are reported in Figure 19 in terms of cumulative passing for dry and wet comminution tests.

Comparing the results obtained in the sieving tests (Figure 20), the wet comminution shows less particles belonging to the +2 mm size class than the dry comminution.

Fig. 19. Plastic bags and films, 20 mm grid, cumulative passing, dry (left) and wet (right) comminution.

The results of laser granulometric analysis are shown in Figure 21 in terms of size distribution for products of dry and wet comminution tests belonging to the -1 mm size class.

bicarbonate LDPE 23 23 thin film LDPE 23 20

in black LDPE 24 27

in blue LDPE 30 30

Table 14. Composition of the samples of plastic bags and films used in the dry and wet

The plastic bags and films have been cut in samples of 50×50 mm in order to reach dimensions suitable for the laboratory blade mill. Moreover, the samples maintained their

The products of the dry and wet comminution tests have been submitted to dry sieving,

The sieving tests have been conducted adopting sieves of ASTM series with 2.0 and 1.0 mm mesh. The results of the sieving tests are reported in Figure 19 in terms of cumulative

Comparing the results obtained in the sieving tests (Figure 20), the wet comminution shows

**0**

**0,1 1,0 10,0 100,0 particle size (mm)**

**25**

**50**

**cumulative passing (%)**

Fig. 19. Plastic bags and films, 20 mm grid, cumulative passing, dry (left) and wet (right)

for products of dry and wet comminution tests belonging to the -1 mm size class.

The results of laser granulometric analysis are shown in Figure 21 in terms of size distribution

**75**

**100**

less particles belonging to the +2 mm size class than the dry comminution.

**Material typology Polymer dry** 

white and red bags containing

bags, with printed character "A"

bags, with printed character "A"

laser granulometry and image analysis.

passing for dry and wet comminution tests.

**0,1 1,0 10,0 100,0 particle size (mm)**

comminution tests.

**0**

comminution.

**25**

**50**

**cumulative passing (%)**

**75**

**100**

content of bulk powder.

**Weigh (%)** 

**comminution wet comminution** 

**particle size (mm)**

Fig. 20. Plastic bags and films, comparison of the products of dry and wet comminution tests in terms of size distribution.

Fig. 21. Plastic bags and films, 20 mm grid, size distribution, size class – 1.0 mm, dry comminution (left) and wet comminution (right), laser granulometry.

Comparing the results obtained in the laser granulometry analysis, the dry and wet comminution tests do not show substantial differences in the size distribution of their products.

After the division in the particle size classes in +2 mm, -2 mm +1 mm, and -1 mm obtained by sieving, image analysis have been conducted on the products of dry and wet comminution tests. The results of image analysis for the plastic bags and films are given in Tables 15-20. Examples of images taken of the dry and wet comminution products are shown in Figure 22 and Figure 23 respectively.

The results of image analysis are reported in the following for all the considered size classes.

Comparing the results of the image analysis for the considered size classes, the difference between dry and wet comminution tests can be observed in the dimensions of the collected particles, measured by the values of *Area, Major Axis Length, Minor Axis Length e Feret Diameter*: the analysed particles generally belong to smaller size classes.

The high values of the parameter *Compactness*, measured in the products of both dry and wet comminution products, are in relation with the irregular morphology of particles, reasonably due to the cut stresses applied by the blades of the mill to very thin material (LDPE).

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 259

Table 16. Plastic bags and films, dry comminution, size class: -2 +1 mm.

Table 17. Plastic bags and films, dry comminution, size class: -1 mm.

Table 18. Plastic bags and films, wet comminution, size class: +2 mm.

• *Flexible multi-layered (plastic and aluminium) sachets containing granular medicine.* 

The flexible multi-layered sachets have been fed to the blade mill without any pretreatment, including the granular medicine they contained. For the dry and wet

**# Obj** 67 67 67 67 67 67 67 **Mean** 4.586 147.115 4.563 2.075 23.798 0.151 2.325 **Min** 0.349 31.033 2.480 0.474 8.716 0.016 0.666 **Max** 15.881 765.458 13.879 3.402 110.257 0.405 4.497 **Std Dev** 2.654 143.863 1.931 0.627 17.288 0.101 0.665 **Std Err** 0.324 17.576 0.236 0.077 2.112 0.012 0.081 **95% Conf** 0.636 34.448 0.462 0.150 4.140 0.024 0.159 **99% Conf** 0.868 47.062 0.632 0.205 5.655 0.033 0.218

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**# Obj** 62 62 62 62 62 62 62 **Mean** 0.886 103.529 2.157 0.847 8.870 0.169 0.974 **Min** 0.070 23.744 0.483 0.173 1.579 0.052 0.300 **Max** 3.647 242.053 5.013 2.413 21.939 0.529 2.155 **Std Dev** 0.725 59.113 1.078 0.479 5.028 0.100 0.428 **Std Err** 0.092 7.507 0.137 0.061 0.639 0.013 0.054 **95% Conf** 0.181 14.714 0.268 0.119 1.251 0.025 0.107 **99% Conf** 0.237 19.338 0.353 0.157 1.645 0.033 0.140

**# Obj** 55 55 55 55 55 55 55 **Mean** 55.820 777.032 16.333 8.129 189.172 0.034 7.174 **Min** 4.040 73.678 4.976 1.902 22.982 0.002 2.268 **Max** 418.924 6791.312 56.129 31.755 1686.727 0.171 23.095 **Std Dev** 81.603 939.346 10.465 5.434 250.611 0.033 4.469 **Std Err** 11.003 126.661 1.411 0.733 33.792 0.004 0.603 **95% Conf** 20.312 233.818 2.605 1.353 62.381 0.008 1.112 **99% Conf** 26.695 307.289 3.423 1.778 81.983 0.011 1.462

Fig. 22. Plastic bags and films, images of the products of dry comminution tests.

Fig. 23. Plastic bags and films, images of the products of wet comminution tests.

The values of the parameter Shape Factor describe a shape of elongated particles.

The statistic parameters, notably the standard deviation, show a high variability in the analysed particles, with standard error and confidence intervals substantially constant for both dry and wet comminution products.


Table 15. Plastic bags and films, dry comminution, size class: +2 mm.


Table 16. Plastic bags and films, dry comminution, size class: -2 +1 mm.

258 Material Recycling – Trends and Perspectives

*+2.0 mm -2.0 mm +1.0 mm -1.0 mm* 

*+2.0 mm -2.0 mm +1.0 mm -1.0 mm* 

The statistic parameters, notably the standard deviation, show a high variability in the analysed particles, with standard error and confidence intervals substantially constant for

**# Obj** 84 84 84 84 84 84 84 **Mean** 110.169 858.617 22.404 11.392 276.048 0.033 10.525 **Min** 0.353 45.314 0.943 0.691 3.999 0.003 0.670 **Max** 460.604 4994.348 54.142 28.985 1175.889 0.277 24.217 **Std Dev** 101.475 828.363 12.335 6.681 232.520 0.038 5.464 **Std Err** 11.072 90.382 1.346 0.729 25.370 0.004 0.596 **95% Conf** 21.700 177.145 2.638 1.429 49.724 0.008 1.168 **99% Conf** 33.195 270.983 4.035 2.186 76.065 0.012 1.787

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

Fig. 23. Plastic bags and films, images of the products of wet comminution tests.

The values of the parameter Shape Factor describe a shape of elongated particles.

Table 15. Plastic bags and films, dry comminution, size class: +2 mm.

both dry and wet comminution products.

Fig. 22. Plastic bags and films, images of the products of dry comminution tests.


Table 17. Plastic bags and films, dry comminution, size class: -1 mm.


Table 18. Plastic bags and films, wet comminution, size class: +2 mm.

• *Flexible multi-layered (plastic and aluminium) sachets containing granular medicine.* 

The flexible multi-layered sachets have been fed to the blade mill without any pretreatment, including the granular medicine they contained. For the dry and wet

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 261

**0,1 1,0 10,0 100,0 particle size (mm)**

Fig. 24. Flexible multi-layered sachets, 20 mm grid, cumulative passing, dry comminution.

Fig. 25. Flexible multi-layered sachets, 20 mm grid, cumulative passing, wet comminution.

The results of laser granulometry analysis are shown in Figure 26 and Figure 27 in terms of size distribution for products of dry comminution tests belonging to the -1 mm +0.85 mm, -

> 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Fig. 26. Flexible multi-layered sachets, 20 mm grid, size distribution, size classes -1 +0.85 mm (left) and -0.85 +0.5 mm (right), dry comminution, laser granulometry.

0.05 0.1 0.5 1 5 10 50 100 500 particle size / µm

density distribution q3\*(x)

**0**

0.85 mm +0.5 mm and -0.5 mm size classes.

0.05 0.1 0.5 1 5 10 50 100 500 1000 particle size / µm

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2

density distribution q3\*(x)

**25**

**50**

**cumulative passing (%)**

**75**

**100**


comminution tests, samples made of 25 sachets (equal to 184.87 g) and of 10 sachets (equal to 73.70 g) have been respectively used.

Table 19. Plastic bags and films, dry comminution, size class: -2 +1 mm.


Table 20. Plastic bags and films, dry comminution, size class: -1 mm.

The products of the dry comminution tests have been submitted to dry sieving, laser granulometry and image analysis.

The sieving tests have been conducted adopting sieves of ASTM series with 1.0 mm, 0.85 mm and 0.50 mm mesh.

The results of the sieving tests are reported in Figure 24 in terms of cumulative passing for the dry comminution tests.

The wet comminution tests have been carried out in order to verify the effect of the use of water on the granular medicine. The results of the tests have been analysed in qualitative terms. In the Figure 25 are shown the images of the products of the comminution test in which 0.4 l of water have been fed to the mill together with the sachets. From the images it can be observed that the sparkling granular medicine has not relevant effects. Moreover, the presence of water allowed reducing the dispersion of powder in the environment during the comminution.

comminution tests, samples made of 25 sachets (equal to 184.87 g) and of 10 sachets (equal

**# Obj** 55 55 55 55 55 55 55 **Mean** 3.638 319.329 4.975 1.915 32.679 0.051 2.039 **Min** 0.354 113.617 1.577 0.451 7.857 0.016 0.671 **Max** 9.377 776.877 10.951 3.989 83.139 0.111 3.455 **Std Dev** 2.309 172.573 2.079 0.847 17.157 0.026 0.695 **Std Err** 0.311 23.270 0.280 0.114 2.313 0.003 0.094 **95% Conf** 0.575 42.956 0.517 0.211 4.271 0.006 0.173 **99% Conf** 0.755 56.454 0.680 0.277 5.613 0.008 0.227

**# Obj** 75 75 75 75 75 75 75 **Mean** 0.679 123.913 2.000 0.809 8.781 0.163 0.851 **Min** 0.049 16.139 0.463 0.136 1.124 0.027 0.249 **Max** 3.544 463.666 5.469 2.341 38.710 0.779 2.124 **Std Dev** 0.606 86.252 1.026 0.527 6.619 0.127 0.377 **Std Err** 0.070 9.960 0.118 0.061 0.764 0.015 0.044 **95% Conf** 0.151 21.470 0.255 0.131 1.648 0.032 0.094 **99% Conf** 0.198 28.216 0.336 0.172 2.165 0.041 0.123

The products of the dry comminution tests have been submitted to dry sieving, laser

The sieving tests have been conducted adopting sieves of ASTM series with 1.0 mm, 0.85

The results of the sieving tests are reported in Figure 24 in terms of cumulative passing for

The wet comminution tests have been carried out in order to verify the effect of the use of water on the granular medicine. The results of the tests have been analysed in qualitative terms. In the Figure 25 are shown the images of the products of the comminution test in which 0.4 l of water have been fed to the mill together with the sachets. From the images it can be observed that the sparkling granular medicine has not relevant effects. Moreover, the presence of water allowed reducing the dispersion of powder in the environment during the

Table 19. Plastic bags and films, dry comminution, size class: -2 +1 mm.

Table 20. Plastic bags and films, dry comminution, size class: -1 mm.

granulometry and image analysis.

mm and 0.50 mm mesh.

the dry comminution tests.

comminution.

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

to 73.70 g) have been respectively used.

Fig. 24. Flexible multi-layered sachets, 20 mm grid, cumulative passing, dry comminution.

Fig. 25. Flexible multi-layered sachets, 20 mm grid, cumulative passing, wet comminution.

The results of laser granulometry analysis are shown in Figure 26 and Figure 27 in terms of size distribution for products of dry comminution tests belonging to the -1 mm +0.85 mm, - 0.85 mm +0.5 mm and -0.5 mm size classes.

Fig. 26. Flexible multi-layered sachets, 20 mm grid, size distribution, size classes -1 +0.85 mm (left) and -0.85 +0.5 mm (right), dry comminution, laser granulometry.

Study on the Feasibility of Hazardous Waste Recycling: The Case of Pharmaceutical Packaging 263

The high values of the parameter *Compactness*, measured in the products of dry comminution products, are in relation with the irregular morphology of multi-layered

The statistic parameters, notably the standard deviation, show a high variability in the analysed particles, due to the simultaneous presence of multi-layered and granular

**# Obj** 11 11 11 11 11 11 11 **Mean** 253.133 73.910 27.032 15.394 131.359 0.193 16.894 **Min** 32.653 38.744 10.198 3.748 35.569 0.092 6.448 **Max** 495.707 136.919 41.900 26.437 227.952 0.324 25.123 **Std Dev** 154.107 27.727 9.990 7.452 63.551 0.072 6.371 **Std Err** 46.465 8.360 3.012 2.247 19.161 0.022 1.921 **95% Conf** 38.360 6.902 2.487 1.855 15.819 0.018 1.586 **99% Conf** 50.413 9.070 3.268 2.438 20.789 0.024 2.084

The results of experimental tests demonstrate the effectiveness of shear stress to comminute

• shear stresses on plastic materials determined an irregular and elongated shape on

• wet and dry conditions are irrelevant on geometric and morphological characteristics of

• statistical analysis on image analysis data evidenced a high variability in geometric and morphological parameters: this is probably due to plasticity property of materials under

• size distribution of the plastic particles after comminution is always greater than 1.0 mm and, therefore, greater than powder eventually contained inside packaging (e.g. in

Considering the outlined results, the comminution process seems to be a feasible treatment for pharmaceutical waste, in order to reduce particle size and to separate packaging

The wet comminution, even if not influential on geometric and morphological

characteristics of output particles, can be adopted to avoid powder dispersion in air.

The comminution tests by blade mill RETSCH – SM 2000 show the following outcomes:

**Area Compact Maj Len Min Len Perim S Factor Feret D** 

particles, reasonably due to the cut stresses applied by the blades of the mill.

particles.

**3. Conclusions** 

output particles;

output particles;

pharmaceutical waste).

investigation and to applied shear stresses;

materials (mainly plastics) and powder eventually contained.

The values of the parameter Shape Factor describe a shape of elongated particles.

Table 21. Flexible multi-layered sachets, dry comminution, size class: -1.0 mm.

primary packaging and waste pharmaceutical product under investigation.

Fig. 27. Flexible multi-layered sachets, 20 mm grid, size distribution, size class -0.5 mm, dry comminution, laser granulometry.

The results of the sieving tests show that the comminuted dry sachets are mostly found in the +1.0 mm and -0.5 mm size classes. In fact, in these classes are respectively collected the multi-layered materials and the granular medicine particles. In the size class –1.0 mm +0.85 mm, the results of laser granulometer analyses show two principal modes, reasonably due to the presence of both multi-layered materials and granular medicine.

After the division in the particle size classes in -1 mm +0.85 mm obtained by sieving, image analysis have been conducted on the products of dry comminution tests. The results of image analysis for the multi-layered sachets are given in Table 21. Examples of images taken of the dry comminution products are shown in Figure 28.

Fig. 28. Flexible multi-layered sachets, images of the products of dry comminution tests.

The high values of the parameter *Compactness*, measured in the products of dry comminution products, are in relation with the irregular morphology of multi-layered particles, reasonably due to the cut stresses applied by the blades of the mill.

The values of the parameter Shape Factor describe a shape of elongated particles.

The statistic parameters, notably the standard deviation, show a high variability in the analysed particles, due to the simultaneous presence of multi-layered and granular particles.


Table 21. Flexible multi-layered sachets, dry comminution, size class: -1.0 mm.
