Printer Friendly

Production and evaluation of briquettes from urban pruning residue and sugarcane bagasse/Producao e avaliacao de briquetes a partir de residuos de poda urbana e bagaco de cana-de-acucar.


Currently, concerns about non-renewable energy sources such as oil and coal are remarkably large. The study of alternatives for clean energy production such as the rational use of biomass is a great way to reduce the use of fossil fuels and the emission of greenhouse gases (Sette Junior et al., 2016; Souza & Vale, 2016; Tavares et al., 2016).

Due to its climate and soil advantages, Brazil has a superior development in agricultural and forest crops; thus, the residues coming from those activities are produced in a very large amount. According to the Sugarcane Industry Union (UNICA, 2017), the State of Sao Paulo was responsible for 56.1% of the national sugarcane production during 2016/2017, corresponding a total volume of 366 million tons. With each processed ton, 320 kilos of sugarcane bagasse are predicted to be generated (UNICA, 2017).

When urban conditions are analyzed, urban residues raise attention for their amount, which continues to grow, and for their deficit of suitable environmental solutions for their proper disposal or reuse. According to the Urban Solid Residues State Report by the Environmental Agency of the State of Sao Paulo (CETESB, 2016), the production of residues was approximately 43000 t d-1 in Sao Paulo, with 860 tons being rejected as trash containing pruning residues from urban trees. According to Meira (2010), there are no references regarding the quantification of urban pruning wastes but the amount is very large and is often directed to landfills where they lose their utility.

Since the Brazilian Act 12.305 of 2010, which established the National Policy of Solid Wastes (PRNS), the disposal in landfills of all kinds of residues, capable of being reused or recycled, has been forbidden. The final disposal must include combustion and other treatments by using technological processes, such as composting and energy reuse, improving the recovery of the system. With this scenario, the main problem is related to the large amount of waste generated and also to the environmental issue when its destination is not adequate.

Among the possible ways of using waste for energy production, briquetting is an interesting one, by applying pressure on a mass of particles, such as biomass wastes, it can form solid and compact blocks with high density (Li & Liu, 2000). The advantages of this method are easy transport and storage, uniform and good burning, and higher heat content (Stolarski et al., 2013).

This study aimed to evaluate the technical feasibility of briquettes produced by residues from urban pruning, sugarcane processing (bagasse), and a mix of both in different percentages.


The materials used were urban pruning residues, collected in Sao Paulo, and sugarcane bagasse (first generation), provided by the sugar and ethanol plant, Usina Santa Rosa, in Porto Feliz, Sao Paulo, Brazil. The residues were stored in sealed plastic bags, in order to preserve their physical conditions until the analyses were done. In the urban pruning residue, species were not identified. The initial moisture contents were 71% in the urban pruning residue and 13% in the bagasse. They were not in contact with the ground and were protected by a canvas.

The bulk density of the residues was determined in accordance to ABNT NBR 6922 (ABNT, 1981) standard. The bulk density of the residues was determined in their initial moisture condition in triplicate.

The proximate analysis of the residues was performed in accordance to ABNT NBR 8112 (ABNT, 1986) standard. Moisture content and the volatile matter of each material was based on ABNT NBR 8112 (ABNT, 1986) standard. For the ash content analysis, TAPPI T211 (TAPPI, 1993) standard was used. Fixed carbon content was calculated in accordance to ABNT NBR 8112 (ABNT, 1986) standard, subtracting the sum between volatile and ash contents. The values were obtained in triplicate.

To obtain the organic solvent content (cyclohexane/ ethanol) (1:1), TAPPI T204 (TAPPI, 1997) standard was used. In order to determine extractives soluble in hot water, a 1000 mL beaker with distilled water was used, based on TAPPI T212 (TAPPI, 1998) standard. The values were obtained in triplicate.

The Klason lignin content was determined in accordance to TAPPI T222 (TAPPI, 1988) standard. The values were obtained in triplicate.

The high heating value of materials (HHV) was determined in triplicate, with approximately 0.5 g of the residues of dry sample, by using a self-contained 'oxygen bomb' calorimeter model C500, from IKA. The same procedure was performed after the output of extractives in cyclohexane/ethanol and in hot water.

Different percentages of the selected biomasses provided a division of five treatments: T1, T2, T3, T4 and T5, respectively made of 100% of urban pruning; 50% urban pruning and 50% sugarcane bagasse; 25% urban pruning and 75% sugarcane bagasse; 10% urban pruning and 90% sugarcane bagasse; 100% sugarcane bagasse. The mixed material of each treatment totalized 300 g, which was adjusted to a 12% moisture content, and then, stored inside a sealed plastic bag until compaction.

Briquettes manufacture was accomplished with a Marcon model hydraulic press, at 1250 kgf cm-2 (122.5 MPa), for a period of 30 s. A 35-mm-internal-diameter cylindrical mold was used with 20 g of material for each sample. This procedure was accomplished without any type of heating sources or binders.

Samples were weighed on an analytical balance and measured with a digital caliper, 120 h after compaction. Apparent density was established by the quotient of the mass and volume of each briquette.

Height and diameter expansion was measured with a digital caliper at the following time intervals: immediately after compaction, 1, 3 and 8 h after compaction as well as prior to the tensile strength test by diametral compression.

Tensile strength test by diametral compression identified the maximum strength to which briquettes can be subjected until rupture occurs in their structure. This test was performed employing the universal test machine EMIC DL30000N, 120 h after briquetting. The force was applied perpendicularly to the compaction pressure. Twelve samples were used in the test for each treatment.

This test was based on ABNT NBR 8740 (ABNT, 1985) standard.

Reference values for the briquetting friability classification are: extremely friable (loss > 30%), averagely friable (loss between 20 to 30%), somewhat friable (loss between 10 to 19%) and slightly friable (loss < 10%).

Apparent density, mechanical resistance and prebriquetting moisture content results were subjected to an analysis of variance, while the comparison between tests was conducted to a 0.05 significance level by F test. When null hypothesis was rejected, means were also compared to a 0.05 significance level, through Tukey test. For bulk density, proximate analysis and heating value, mean, variance and side deviation analysis were made. Statistical analyses were run with R 3.0.1. and Microsoft Excel software.


The bulk density results for both materials in their initial conditions are shown on Table 1.

Sugarcane bagasse had inferior bulk density when compared to urban pruning. The lower the bulk density the greater its volume, consequently there is a greater amount of available material for transporting and storing.

According to Vale et al. (2017), sawdust in general has bulk density varying from 100 to 300 kg m-3. It can be affirmed that the obtained value in urban pruning fits these standards, given the fact that the material is a result of several wood species planted as city trees.

Table 2 presents the proximate analysis, extractives and Klason lignin contents, and heating value results for urban pruning residues and sugarcane bagasse.

Nakashima et al. (2014) found a percentage of 84.03 for the content of volatile matter of sugarcane bagasse, close to that found in this study (84%). High volatile matter content provides an accelerated burning process, because the gases are emitted quickly in larger units of burning area. A successful alternative for materials with high volatile matter content, such as sugarcane bagasse, is the compaction, since this process reduces the superficial area and provides greater densification of residues, slowing down the burning rate of a fuel.

According to Santos et al. (2011), the ashes content is the fraction that remains as a residue after combustion of the material in solid state, the fixed carbon. A good solid fuel must have ashes content inferior to 3%. Sugarcane bagasse ashes (2.61) fell into the desired result. The analyzed urban pruning material showed a high value of ashes content (9.57%), which can be explained by the large quantity of contaminants, such as dirt, dust and sand, probably mixed with the material when collected. High ashes content may be disadvantageous, since it can form solid residues incrusted in the furnace's burners.

A lot of the energy content of the material is expressed in the form of fixed carbon, related to the energy and thermal resistance of the fuel, promoting a slower burning (Santos et al., 2011). The result found for urban pruning (16.69%) is plausible compared with that of the eucalyptus wood studied by Silva et al. (2015), which was 17.9%. The result obtained for sugarcane bagasse was 13.39%, which is comparable to the value of 12.87% obtained by Brasil et al. (2015).

The value of total extractives for bagasse (11.51%) is superior to the value 6.1% obtained by Gouveia et al. (2009). According to Moutinho et al. (2016), high extractives and lignin contents tend to increase the calorific value, a positive characteristic for energy production.

Lignin is a major contributor to the energy potential of solid biofuels due to its high carbon content composition, providing greater thermal resistance and delaying its decomposition (Gani & Naruse, 2007). Urban pruning residue exhibited higher heating value than sugarcane bagasse (Table 2).

Heating value is an excellent parameter to assess the energy potential of biomass fuels (Protassio et al., 2011).

The high heating value (HHV) obtained for urban pruning biomass (4702.63 kcal [kg.sup.-1]) is higher than the HHV found in the study of Eucalyptus grandis sawdust performed by Goncalves et al. (2013), which was 4229 kcal [kg.sup.-1].

According to Munalula & Meincken (2009), the heating value increases with the carbon content. Urban pruning residue showed greater fixed carbon content (Table 2), which also had superior HHV value when compared to sugarcane bagasse.

Table 3 shows the percentage of residues for each treatment, as well as the adjusted moisture content for compaction.

For all treatments, the moisture content was very close, ranging from 11.8 to 12.3%. This moisture content is suitable for the production of briquettes (10 to 12%).

Table 4 presents mean apparent density of briquettes for each treatment.

The apparent density values were similar to those obtained by Goncalves et al. (2013) for briquettes of Eucalyptus grandis sawdust. Quirino et al. (2012) performed a study of the apparent density of briquettes produced with residues of Eucalyptus sp. and obtained values between 1132 and 1343 kg [m.sup.-3], higher than the values of this study.

Treatment T1 showed greater apparent density. The lower the percentage of urban pruning residue the lower the apparent density. All treatments differed between one another in this analysis, except for T3 and T4.

The processing of residues (bulk density) in briquettes (apparent density) favors stocking and transporting, since material compaction causes better use of space and decrease of volume. Urban pruning residue volume suffered a reduction of 864% and sugarcane bagasse of 1567%.

Figure 1A shows that T5 exhibited the maximum diametric expansion, around 1%. Figure 1B shows the height expansion of briquettes, with T5 being the treatment with the maximum expansion of approximately 8%. The objective of Figure 1 was to present the behavior of the briquetting expansion curve, showing the period in which the expansion stabilized.

Yamaji et al. (2013) studied hygroscopicity of different biomasses and sugarcane bagasse showed one of the highest values in height expansion, demonstrating larger interference on the moisture content of briquettes. In addition to moisture absorption, expansion occurs due to the poor particle aggregation of the material. The same behavior was observed for sugarcane bagasse in this study.

Table 5 shows tensile strength and briquettes friability tests for five treatments.

Amaral et al. (2015) obtained mean maximum load between 50 kgf (490.3 N) and 52 kgf (509.9 N) for briquettes produced from two species of bamboo, that is, higher than the values of treatments T4 and T5 and lower than the values of treatments T1 to T3 of this study.

The low resistance of T4 and T5 briquettes in comparison to the others may have occurred because the particle size is not ideal for the compaction process, about 82% of the biomass residue was inside the thick particle class. According to the study of Kaliyan & Morey (2009), particles of different materials with smaller sizes resulted in pellet durability, resulting from a better accommodation and adherence of particles of the compacted material.

Based on the obtained results, T1 and T2 were the best treatments regarding the friability, since they proved to be slightly and averagely friable, respectively.

The lower the friability rate, the more resistant the briquette. It is likely that such behavior is related to the good conformation of the particles of the material, being juxtaposed to each other in a more organized manner, during the formation of the briquette (Dias Junior et al., 2014).


The addition of urban pruning residue provided improved mechanical performance to briquettes, attesting T1 and T2 as the most satisfactory treatments.



ABNT--Associacao Brasileira de Normas Tecnicas. NBR 6922: Carvao vegetal: Ensaio fisico determinacao da massa especifica (densidade a granel). Rio de Janeiro: ANBT, 1981. sp.

ABNT--Associacao Brasileira de Normas Tecnicas. NBR 8740. Carvao vegetal: Determinacao do indice de quebra e abrasao Metodo de ensaio. Rio de Janeiro: ANBT, 1985. sp.

ABNT--Associacao Brasileira de Normas Tecnicas. NBR 8112: Carvao vegetal: Analise imediata. Rio de Janeiro: ABNT, 1986. sp.

Amaral, P. M.; Yamaji, F. M.; Oliveira, P. B. M. de; Silva, D. A. da; Silva, J. M. S. da; Guerra, S. P. S. Caracterizacao quimica, fisica e mecanica de briquetes de duas variedades de bambu. Revista do Instituto Florestal, v.27, p.73-81, 2015. rif.2015.006

Brasil, D. S.; Martins, M. P.; Nakashima, G. T.; Yamaji, F. M. Use of sugarcane bagasse and candeia waste for solid biofuels production. Floresta, v.45, p.185-192, 2015. rf.v45i1.36502

CETESB--Companhia Ambiental do Estado de Sao Paulo. Inventario estadual de residuos solidos urbanos. 2016. Disponivel em: < residuos-urbanos-saude-construcao-civil/publicacoes-erelatorios-2/>. Acesso em: Jan. 2018.

Dias Junior, A. F.; Andrade A. M.; Costa Junior, D. S. Caracterizacao de briquetes produzidos com residuos agroflorestais. Pesquisa Florestal Brasileira, v.34, p.225-234, 2014. https://doi. org/10.4336/2014.pfb.34.79.613

Gani, A.; Naruse, I. Effect of cellulose and lignin content on pyrolysis and combustion characteristics for several types of biomass. Renewable Energy, v.32, p.649-661, 2007. https://doi. org/10.1016/j.renene.2006.02.017

Goncalves, B. F.; Yamaji, F. M.; Fernandez, B. O.; Roz, A. L. da; Floriano, F. S. Caracterizacao e comparacao entre diferentes granulometrias de serragem de Eucalyptus grandis para confeccao de briquetes. Revista do Instituto Florestal, v.25, p.205-213, 2013.

Gouveia, E. R.; Nascimento, R. T. do; Souto-Maior, A. M.; Rocha, G. J. de M. Validacao de metodologia para a caracterizacao quimica de bagaco de cana-de-acucar. Quimica Nova, v.32, p.1500-1503, 2009.

Kaliyan, N.; Morey, R. V. Factors affecting strength and durability of densified biomass products. Biomass & Bioenergy, v.33, p.337-359, 2009.

Li, Y.; Liu, H. High-pressure densification of wood residues to form an upgraded fuel. Biomass & Bioenergy, v.19, p.177-186, 2000.

Meira, A. M. de. Gestao de residuos da arborizacao urbana. Piracicaba: Universidade de Sao Paulo, 2010. 178p. Tese Doutorado. https://

Moutinho, V. H. P.; Rocha, J. J. M. da; Amaral, E. P. do; Santana, L. G. de M.; Aguiar, O. J. R. de. Propriedades quimicas e energeticas de madeiras amazonicas do segundo ciclo de corte. Floresta e Ambiente, v.23, p.443-449, 2016.

Munalula, F.; Meincken, M. An evaluation of South African fuelwood with regards to calorific value and environmental impact. Biomass & Bionergy, v.33, p.414-420, 2009. biombioe.2008.08.011

Nakashima, G. T.; Martins, M. P.; Silva, D. A.; Chrisostomo, W.; Yamaji, F. M. Aproveitamento de residuos vegetais para a producao de briquetes. Revista Brasileira de Ciencias Ambientais, v.34, p.22-29, 2014.

Protassio, T. P.; Bufalino, L.; Tonoli, G. H. D.; Couto, A. M.; Tugilho, P. F.; Guimaraes Junior, M. Relacao entre o poder calorifico superior e os componentes elementares e minerais da biomassa vegetal. Pesquisa Florestal Brasileira, v.31, p.122-133, 2011. https://doi. org/10.4336/2011.pfb.31.66.113

Quirino, W. F.; Pinha, I. V. de O.; Moreira, A. C. de O.; Souza, F. de; Tomazello Filho, M. Densitometria de raios x na analise da qualidade de briquetes de residuos de madeira. Scientia Forestalis, v.40, p.525-536, 2012.

Santos, R. C. dos; Carneiro, A. de C. O.; Castro, R. V. O.; Pimenta, A. S.; Castro, A. F. M. M.; Marinho, I. V.; Boas, M. V. Potencial de briquetagem de residuos florestais da regiao do Serido, no Rio Grande do Norte. Pesquisa Florestal Brasileira, v.31, p.285-294, 2011.

Sette Junior, C. R.; Freitas, P. de C.; Freitas, V. P.; Yamaji, F. M.; Almeida, R. de A. Production and characterization of bamboo pellets. Bioscience Journal, v.32, p.922-930, 2016. https://doi. org/10.14393/BJ-v32n4a2016-32948

Silva, D. A.; Yamaji, F. M.; Barros, J. L.; Roz, A. L. da; Nakashima, G. T. Caracterizacao de biomassas para a briquetagem. Floresta, v.45, p.713-722, 2015.

Souza, F. de; Vale, A. T. do. Densidade energetica de briquetes de biomassa lignocelulosica e sua relacao com os parametros de briquetagem. Pesquisa Florestal Brasileira, v.36, p.405-413, 2016.

Stolarski, M. J.; Szczukowski, S.; Tworkowski, J.; Krzyzaniak, M.; Gulczynski, P.; Mleczek, M. Comparison of quality and production cost of briquettes made from agricultural and forest origin biomass, Renewable Energy, v.57, p.20-26, 2013. https://doi. org/10.1016/j.renene.2013.01.005

TAPPI--Technical Association of Pulp and Paper Industry. Standard Method T222 om-88: Tappi Test Methods. Peachtree Corners: TAPPI, 1988. sp.

TAPPI--Technical Association of Pulp and Paper Industry. Standard Method T211 om-93: Tappi Test Methods. Peachtree Corners: TAPPI, 1993. sp.

TAPPI--Technical Association of Pulp and Paper Industry. Standard Method T204 om-97: Tappi Test Methods. Peachtree Corners: TAPPI, 1997. sp.

TAPPI--Technical Association of Pulp and Paper Industry. Standard Method T212 cm-98: Tappi Test Methods. Peachtree Corners: TAPPI, 1998. sp.

Tavares, B.; Sene, L.; Christ, D. Valorization of sunflower meal through the production of ethanol from the hemicellulosic fraction. Revista Brasileira de Engenharia Agricola e Ambiental, v.20, p.1036-1042, 2016. v20n11p1036-1042

UNICA--Uniao da Industria de Cana-de-acucar. Safra 2016/2017. Disponivel em: <> Acesso em: Jan. 2018.

Vale, A. T. do; Araujo, T. A. de; Fortes, M. M.; Lima, M. B. de O.; Josino, M. N. Qualificacao de briquetes produzidos com mistura de residuos solidos urbanos e rejeitos agricolas e residuos. Enciclopedia Biosfera, v.14, p.1-5, 2017.

Yamaji, F. M.; Vendrasco, L.; Chrisostomo, W.; Flores, W. de P. Analise do comportamento higroscopico de briquetes. Energia na Agricultura, v.28, p.11-15, 2013.

Ana K. de G. Smith (1), Leticia S. Alesi (1), Luciano D. Varanda (1), Diego A. da Silva (1), Luis R. O. Santos (1) & Fabio M. Yamaji (1)

(1) Universidade Federal de Sao Carlos/Departamento de Ciencias Ambientais/Programa de Pos-Graduacao em Planejamento e Uso de Recursos Renovaveis. Sorocaba, SP. E-mail: 0000-0003-2896-7259; 0000-0001-6364-3028; (Corresponding author)--ORCID: 0000-0003-1193-4944; 0000-0002-2552-7672; 0000-0003-4649-7852; 0000-0002-0908-8163

Caption: Figure 1. Results of diametric expansion of briquettes (A); Results of height expansion of briquettes (B)
Table 1. Bulk density of the residues

Material               M *       Bulk density
                    (%d.b. *)   (kg [m.sup.-3])

Urban pruning       71 (0.10)    117.90 (5.75)
Sugarcane bagasse   13 (0.10)    85.93 (5.43)

* M--Moisture; d.b--Dry basis; standard deviation in parenthesis

Table 2. Proximate analysis, extractives and Klason lignin contents
and heating value of the residues

                                Proximate analysis

                       Initial          Ashes         Volatile
Material              moisture           (%)           matter

Urban pruning       71.00 (0.10)     9.57 (0.96)    74.73 (1.40)
Sugarcane bagasse   13.00 (0.10)     2.61 (0.57)    84.00 (0.36)

                    Proximate analysis

Material               carbon

Urban pruning       16.69 (2.02)
Sugarcane bagasse   13.39 (0.69)

                       Extractives contents

                      Hot water     Cyclohexane/
                    soluble mean    ethanol mean       Total
Urban pruning       10.08 (0.31)     2.11 (0.14)    12.19 (0.31)
Sugarcane bagasse    9.51 (0.55)     2.00 (0.10)    11.51 (0.50)

                    Klason lignin contents

                    Klason lignin
                     content (%)

Urban pruning           30.82
Sugarcane bagasse       22.11

                             Heating value

                        HHV *       HHV EXT C/E *

Urban pruning          4702.63         4291.34        4152.82
Sugarcane bagasse      4410.26         4722.46        5018.75

* HHV--High heating value; HHV EXT C/E--High heating value with
extractives removed with Cyclohexane/ethanol; HHV EXT
[H.sub.2]O--Higher heating value with extractives removed with
water; standard deviation in parenthesis

Table 3. Treatments and adjusted moisture content prior to

Treatment   Urban pruning   Sugarcane bagasse   Moisture content
                         (%)                       (%d.b. *)

T1               100                0             11.9 (0.47)
T2               50                50             12.1 (0.20)
T3               25                75             12.2 (0.67)
T4               10                90             11.8 (0.25)
T5                0                100            12.3 (0.17)

T1-100% of urban pruning; T2-50% urban pruning and 50% sugarcane
bagasse; T3-25% urban pruning and 75% sugarcane bagasse; T4-10%
urban pruning and 90% sugarcane bagasse; T5-100% sugarcane bagasse;
* d.b.--Dry basis; Standard deviation in parenthesis

Table 4. Mean apparent density of briquettes

Treatment        Mean apparent        Standard
            density (kg [m.sup.-3])   deviation

T1                 1018.90 d            31.65
T2                 968.96 c             11.46
T3                 915.94 b             10.03
T4                 903.85 b             9.97
T5                 845.58 a             51.72

T1-100% of urban pruning; T2-50% urban pruning and 50% sugarcane
bagasse; T3-25% urban pruning and 75% sugarcane bagasse; T4-10%
urban pruning and 90% sugarcane bagasse; T5-100% sugarcane bagasse;
Equal lowercase letters in the columns imply treatments with
equivalent means, that is, that do not differ between them, at a 0.05
significance level

Table 5. Tensile strength and briquettes friability

Treatment   Mean maximum    Standard    Mean maximum
            tension (MPa)   deviation    load (kgf)

T1             1.54 a         0.17        167.14 a
T2             0.92 b         0.05        107.56 b
T3             0.60 c         0.06        72.80 c
T4             0.35 d         0.03        43.84 d
T5             0.24 e         0.40        31.19 e

Treatment   Standard    Friability   Moisture content
            deviation    rate (%)        (%d.b.)

T1            17.38        3.49            13.7
T2            5.50        21.37            12.7
T3            06.09       46.17            11.9
T4            3.99        67.13            11.2
T5            4.45        69.78            10.8

* T1-100% of urban pruning; T2--50% urban pruning and 50% sugarcane
bagasse; T3--25% urban pruning and 75% sugarcane bagasse; T4-10%
urban pruning and 90% sugarcane bagasse; T5-100% sugarcane bagasse;
Equal lowercase letters in the columns imply treatments with
equivalent means, that is, that do not differ between them, at a 0.05
significance level
COPYRIGHT 2019 ATECEL--Associacao Tecnico Cientifica Ernesto Luiz de Oliveira Junior
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2019 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:de G. Smith, Ana K.; Alesi, Leticia S.; Varanda, Luciano D.; da Silva, Diego A.; Santos, Luis R.O.;
Publication:Revista Brasileira de Engenharia Agricola e Ambiental
Date:Feb 1, 2019
Previous Article:Microstructure and flow properties of lyophilized mango pulp with maltodextrin/Microestrutura e propriedades de escoamento da polpa liofilizada de...
Next Article:Reduction of fuel consumption using driving strategy in agricultural tractor/Reducao do consumo de combustivel usando estrategia de conducao em...

Terms of use | Privacy policy | Copyright © 2022 Farlex, Inc. | Feedback | For webmasters |