In this paper were performed laboratory experiments regarding processing by pyrolysis process of urban waste components (wood, paper, textiles). The authors designed and developed an experimental equipment and were applied several technological parameters such as temperature and plant maintenance time. The analysis of physical and chemical properties of obtained products found that pyrolysis process can be an effective alternative treatment of urban waste to reduce their quantity and to increase environmental protection

Ana DONIGA

Dumitru DIMA

Elisabeta VASILESCU

Paula POPA

The Annals of “Dunarea de Jos” University of Galati Fascicle IX Metallurgy and Materials Science

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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 4 – 2011, ISSN 1453 – 083X 
 
 
 
 
RESEARCHES REGARDING WASTE PROCESSING OF CELLULOSIC 
MATERIALS BY PYROLYSIS PROCESS 
 
Ana DONIGA, Dumitru DIMA, Paula POPA,  
Elisabeta VASILESCU 
“Dunărea de Jos” University of Galaţi  
email: ana_doniga@yahoo.com 
 
ABSTRACT 
 
In this paper were performed laboratory experiments regarding processing by 
pyrolysis process of urban waste components (wood, paper, textiles). The authors 
designed and developed an experimental equipment and were applied several 
technological parameters such as temperature and plant maintenance time.  The 
analysis of physical and chemical properties of obtained products found that 
pyrolysis process can be an effective alternative treatment of urban waste to reduce 
their quantity and to increase environmental protection. 
 
KEYWORDS: urban waste, physical and chemical properties 
 
1. Introduction 
 
The waste amount at global level is currently 
increasing. This is due, firstly, to the global 
population growth and the urbanization increasing 
process and secondly, to the high rate of 
industrialization. These contribute to increasing 
quantity and diversification of solid waste, not only in 
developed countries but also in developing countries. 
Waste concentration is much higher in cities than in 
rural areas, because of the urban population tendency 
to consume more than the rural one. Therefore, 
currently, there is more acute the problem of waste 
reduction, recycling and recovering a part of the 
waste, or by destruction, using different methods of 
those who cannot be recovered.[1] 
Recycling and recovering of urban waste at 
global level is aiming, firstly, to an advanced 
processing (and therefore decrease the amount) and, 
secondly, to reduce pollution and environmental 
protection. Products obtained from these processes 
can be used in other industries. 
The largest amount of urban waste is organic 
(biomass): wood products, plastics, paper, cardboard, 
textiles, food waste, rubber, leather, etc.. The main 
substances contained in municipal solid waste are: 
cellulosic substances, albuminoidal and protein, fat, 
minerals, etc. 
There are different methods of waste 
processing:  biological, mechanical, thermal, etc. 
Among the most commonly used heating methods are 
drying, incineration, pyrolysis and co-incineration. 
Pyrolysis is a thermal process occurring in the 
absence of oxygen and consists of successive 
decomposition of the main constituents (cellulose, 
lignin, hemicellulose), which have different thermal 
stability. The process of breaking and rearrangering of 
the bonds in polymers (constituents) that form the 
biomass, leading to a large number of products, 
grouped into three fractions: 
- solid fractions (coal) is the solid residue formed 
mostly of carbon; 
- liquid fraction (bio-oil, tar, steam): a mixture of 
compounds, volatile pyrolysis temperature, which 
then condenses at ambient temperature. They are high 
molecular weight components; 
        - gas fraction: CO, CO2, H2, hydrocarbons. They 
are low molecular weight components. Considering 
that biomass has as basic component the cellulose, we 
state that the pyrolysis (thermal decomposition) is 
governed by the following scheme (Figure 1) [2]. 
In terms of energy, pyrolysis reactions are 
endothermic and have multiple effects: 
 - removal and transformation (neutralization) of 
waste and other waste type, take into account the 
environmental conditions; 
- reducing of treated waste in volume and weight; 
        - obtaining liquid and gaseous fuels. 
The composition and quality of products obtained 
from pyrolysis depend on the processed waste quality, 
but also on the equipment operating and service 
conditions. With appropriate equipments, some 
products can be separated and recovered completely 
as fuel or raw material for chemical industry.  
 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 4 – 2011, ISSN 1453 – 083X 
 
 
 
 
Fig. 1. Cellulose pyrolysis. 
 
Pyrolysis can be applied in several ways, 
depending on working conditions: [3] 
- low temperature pyrolysis (400 ... 600 ° C) and 
medium temperature  (600 ... 1000 ° C);  
- high temperature pyrolysis (2000 ° C); 
- pyrolysis in molten metal bath salts or;  
- vacuum pyrolysis.  
 
2. Materials used and experimental 
procedure 
 
To achieve the laboratory experiments, were 
used household waste as wood flour, paper packaging 
(cardboard) and yarns [4]. All these materials have 
approximately the same composition: 
- Cellulose (C6H10O5) x, proportion of 40 ... 
50%;  
- Similar hemicellulose xylan (C5H8O4) m, 
proportion of 15 ... 25%;  
- Lignin [C9 H10 .3 (OCH 3) 0.9 to 1.7] n 
about. 20 ... 30% (characteristic for wood – it is found 
in bole, leafage and bark) 
- Organic substances: polysaccharide, 
pentozans, hexozans, resins, tannins, dyes, waxes, 
alkaloids.  
 
To carrying out the pyrolysis process in optimal 
conditions, fine particles materials are necessary. It 
has been selected wood flour and cardboard was cut 
into very fine strips, while for textile were chosen 
cotton waste. 
The experiments were conducted in the 
University "Dunarea de Jos" of Galati, Faculty of 
Metallurgy, Materials Science and Environment and 
Faculty of Chemistry laboratories.  
It has been established a technology to carry out 
the pyrolysis process, based on the following steps 
(Fig. 2). 
 
 
 
 
 
 
 
 
 
 
 
 
Fig.2. Pyrolysis process technology diagram for wood waste. 
Pyrolysis Vapor condensation 
Gas absorption 
Solid pyrolysis 
products 
Liquid separation Water + gas absorbed from 
pyrolysis 
Washing waters 
Gas 
 
     Chip 
N2 
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FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 4 – 2011, ISSN 1453 – 083X 
 
 
It was designed an equipment consisting of an 
Automatica electric furnace with silit bar heaters in 
which an air-tight enclosure with protective 
atmosphere was entered. 
For a complete removal of resulting gas, it was 
introduced nitrogen, circulating throughout the 
deployment process at a pressure of 1.2x105 Pa. 
For gas capture, two vessels for washing plastic 
(PET) were used and introduced in distilled water and 
were connected to the pyrolysis chamber. Resulting 
gas were dissolved in water and the liquid can be 
analyzed. The third plastic container was left empty, 
to capture the last amount of gas insoluble in water 
(Fig.3). 
 
 
 
Fig.3. Pyrolysis equipment. 
 
Pyrolysis process was carried out according to 
the following steps:  
- sample preparation. Waste samples were dried 
in the oven, placed in two metal tanks and were 
weighed on an electronic balance, then placed inside 
the enclosure work. 
- pyrolysis process. We have chosen several 
temperatures: 6000C, 4000C, 3000C, 2000C. 
Maintenance times: 4 hours, 1 hour, ½ hours. 
Nitrogen continuously circulated through the 
equipment.  
- process ending. The equipment stops by 
furnace cooling after the established time and nitrogen  
flows through to fully capture any resulting gas; 
- sampling and laboratory analysis.  
 
Final, pyrolysis products are presented as three 
fractions: 
 
-  solid fractions of small particles (wires) of 
coal with original waste size and shape (Fig. 4); 
-  liquid fraction, collected in a silicone rubber 
coil, connected to the first gas capture container; 
-  gas fraction, dissolved in distilled water 
containers. We used this method to determine the 
physical properties of resulted gases.
 
    
 
Fig. 4. Solid fraction resulting from pyrolysis process: 
a – from wood flour, b – from paper. 
  
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FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
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3. Experimental results 
 
In the process of pyrolysis were analyzed the 
resulting three fractions as follows: Solid fraction. 
The obtained coal sample was weighed and compared 
to initial sample in terms of mass, after its chemical 
composition was analyzed. 
In Tables 1, 2, 3 are presented the main 
parameters of the process and mass samples, initial 
and final mass loss after thermal processing. 
 
Applied thermal regime and mass loss of analyzed samples 
 
Table 1. Wood Flour 
 
Thermal regime Solid mass fraction (g) Weight loss (ΔG) 
Sample Temperature 
(0C) 
Time 
(hours) initial G0 final G1 (g) % 
B1 600 4 20 5.30 14.70 73.5 
B2 600 1 20 6.40 13.60 68.0 
B3 400 1 20 6.59 13.41 67.07 
B4 300 1 20 8.10 11.90 59.5 
B5 200 1/2 20 8.70 11.30 56.5 
  
Table 2. Paper waste 
 
Regime Solid mass fraction (g) Weight loss (ΔG) 
Sample Temperature 
(0C) 
Time 
(hours) initial G0 final G1 (g) (%) 
H1 300 1 20 6.90 13.10 65.50 
H2 300 1/2 20 7.49 12.51 62.55 
H3 200 1 20 9.23 10.77 53.85 
H4 200 1/2 20 11.17 8.83 44.15 
 
Table 3. Textile waste 
 
Thermal regime Solid mass fraction(g) Weight loss (ΔG) 
Sample Temperature 
(0C) 
Time 
(hours) initial G0 final G1 (g) % 
T1 600 1 20 3.95 16.05 80.25 
T2 400 1 20 7.49 12.51 62.55 
T3 300 1 20 9.07 10.93 54.65 
               ΔG mass loss is determined by the relationship:  ΔG = G0 – G1 
 
The diagrams in Figure 5 show the variation of mass  loss depending on process parameters and sample’s 
material. 
 
                  B1  B2   B3  B4  B5                           H1  H2   H3   H4                                    T1   T2    T3 
 
Fig.5. Mass loss resulting from pyrolysis: a) wood flour, b) board, c) textile. 
0
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60
70
80
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60
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FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 4 – 2011, ISSN 1453 – 083X 
 
 
Mass loss increases with increasing temperature 
and working time, also is quite important even at low 
temperatures (200 ... 3000C). On an LECO equipment 
was analyzed the result coal of pyrolysis of wood and 
cardboard waste. The carbon percentage shows the 
process efficiency and solid fraction recovery 
possibilities (Table 4). Carbon content is high, so the 
thermal decomposition is advanced even at low 
temperatures.  
For identification of other elements present in 
the solid fraction was used XRF spectrometer. The 
results are presented in Table 5. 
 
Table 4. Carbon and sulphur content of analyzed samples 
 
Thermal regime 
Material Sample Temperature 
(0C) 
Time 
(hours) 
Carbon 
(%) 
Sulphur 
(%) 
Wood flour B4 300 1 73.24 0.30 
Wood flour B5 200 1/2 71.90 0.32 
Wood flour B6* 300 1 70.95 0.34 
Cardboard H1 300 1 57.33 0.18 
Cardboard H2 300 1/2 56.89 0.17 
Cardboard H3 200 1 53.44 0.18 
*B6 sample was obtained by pyrolysis of wood waste in the absence of nitrogen.  
 
Table 5. The content of the main elements present in pyrolysis material 
 
Sample  Zn Fe Mn Cr Ca K 
H1 (Cardboard) 31.61 353.93 41.91 386.01 15728.2 28552.15 
B4 (Wood flour) 26.29 321.09 39.62 335.07 15310.34 27698.71 
T3 (Textile) 442.91 362.89 - 396.46 12162.84 3033.41 
 
The analyzed samples were subjected to the same 
working regime (temp = 3000 C, time = 1 hour). 
Liquid fraction resulted is a strong smelling tar, dark 
brown color and consistency of oil. Because small 
amount were obtained, could not achieve a complete 
material analysis. The resulting gas from pyrolysis 
was dissolved in distilled water to determine the 
physicochemical properties of the resulting liquid, 
using a multifunctional analyzer with Consort C862. 
For each sample were determined pH, electrical 
potential (V), conductivity (λ), resistivity (ρ) and total 
dissolved salts (TDS).  
The results are presented in Table 6. 
 
Table 6. Physical properties of dissolved gases 
 
Sample code 
Parameter Measurement units Wood flour  
(B4) 
Cardboard 
(H1) 
Textile 
(T3) 
pH upH 3.74 4.44 3.67 
V eV 164 116 185 
λ μS/cm 62.5 24.9 141 
ρ kΩ·cm-1 15.99 47.5 7.09 
TDS mg/L 37.1 11.2 83.6 
 
All liquid samples analyzed have low acidic pH. 
The sample’s acidity is given by the content of 
organic acids and carbon dioxide, retained as a result 
of distilled water barbotage of the gas resulting from 
the pyrolysis process. 
Liquid samples have variable conductivity, the 
highest values occurring in those from the textile 
waste. The total content of dissolved salts recorded 
higher values throughout the textile waste. 
Gas fraction. For gas analysis was conducted a 
wood waste pyrolysis at a temperature of 3000 C for 
one hour.  
Gases were captured in two plastic containers, 
without using distilled water. It was used a 
combustion gas analyzer MSI type. The results are 
shown in Table 7. 
The pyrolysis conditions applied resulted in a 
high content of NO and CO. 
 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 4 – 2011, ISSN 1453 – 083X 
 
 
Table 7. Gas fraction composition of wood waste pyrolysis 
 
Container O2 (% vol) 
SO2 
(ppm) 
NO 
(ppm) 
CO 
(ppm) 
CO2 
(% vol) 
1 10.8 281 509.5 853.6 9.8 
2 19.4 35 412.3 543.8 1.5 
 
4. Conclusions 
 
The experimental research led to the following 
observations: 
     - the organic decomposition by pyrolysis process 
was carried out in a simple equipment with low 
energy consumption;  
     - the low temperature and time process;  
     - the small amount of solid fractions after 
pyrol.ime and working conditions; 
    - the resulted coal is called "biological coal" and it 
has a high mineral content, useful as fertilizer in 
agriculture;  
       - the captured gases contain a high percentage of 
NO and CO. In an industrial gas plant, the resulted 
gas can be used as fuel in the pyrolysis process, 
thereby eliminating carbon monoxide; 
- the possibility of energy recovery products;  
    - the possibility of a wide variety of organic waste;  
    - low environmental impact. 
From observations during experimental research it 
can be concluded that in an urban area, depending on 
waste storage and processing possibilities, pyrolysis 
may be preferred to other waste treatment processes 
due to the advantages it presents: 
        - waste consumption;  
        - use of charcoal as a solid material for 
wastewater treatment, including those resulting from 
the pyrolysis. 
     
 
References 
 
[1]. Ndiaye F. T. - Pyrolyse de la biomasse en reacteur cyclone-
recherche des conditions optimales de fonctionnement, I.N.P. 
Lorraine, 2008. 
[2]. Ion V.Ion - Energia biomasei – Energie nr.7 (38), 2006, p. 14-
30. 
[3]. G.I.E. PROCEDIS - Pyrolyse – gazéification de dechets 
solides, Etude ADEME/ Procedis -2004. 
[4]. G. Finqueneisel – Les mécanismes primaires de pyrolyse de la 
biomasse, Université de Metz – 2009. 
 
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Researches Regarding Waste Processing of Cellulosic Materials by Pyrolysis Process

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Researches Regarding Waste Processing of Cellulosic Materials by Pyrolysis Process

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