Review Article

Utilization of Non-Wood Fibers as Raw Materials for Pulp and Paper Production in Pakistan: A Review

Muhammad Umair Khan1*, Abdur Rehman1, Mansoor Ali Khan1, Abdur Rahman Khan1, Sajid Ali1 and Zeeshan Ahmad2

1Pakistan Forest Institute, Peshawar, Khyber Pakhtunkhwa, Pakistan; 2Department of Industrial Engineering, University of Engineering and Technology Peshawar, Khyber Pakhtunkhwa, Pakistan.

Received | October 04, 2023; Accepted | October 11, 2024; Published | October 26, 2024

*Correspondence | Muhammad Umair Khan, Pakistan Forest Institute, Peshawar, Khyber Pakhtunkhwa, Pakistan; Email: umairicp7@gmail

Citation | Khan, M.U., A. Rehman, M.A. Khan, A.R. Khan, S. Ali and Z. Ahmad. 2024. Utilization of non-wood fibers as raw materials for pulp and paper production in Pakistan: A review. Pakistan Journal of Forestry, 74(2): 53-62.

DOI | https://dx.doi.org/10.17582/journal.PJF/2024/74.2.53.62

Keywords | Non-wood fiber, Raw material types, Suitability, Pulp and paper production

Copyright: 2024 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Introduction

The global as well as Pakistan’s pulp and paper industries have been experiencing rapid growth, leading to a substantial surge in demand for raw materials used in their production. Paper and pulp mills provide a wide range of goods for different uses, making them essential to both the national and international economies. Pakistan is poor in forest cover. Most of the raw material is imported to meet the demand. However Pakistan is an agriculture country which produces a large amount of fruits, vegetables, cereals and agriculture residues. These residues can be utilized as a source of fibers in the production of pulp, paper and paperboards. The past few decades have seen a constant rise in the use of paper in wealthy nations like Japan, the European Union, and the United States, due to the rapid industrial expansion and urbanization (Latta et al., 2016). Due to the increasing demand, Concerns about the environmental consequences of forest harvesting have increased the pressure on logging (Ashori, 2006; Madakadze et al., 2010; Mossello et al., 2010). Consequently, there is a necessity for affordable alternative raw materials and processes. Non-wood fibers, like those found in annual plants and agricultural waste, offer potential sources for making pulp and paper with desirable qualities (Rosa et al., 1999; Sridach, 2010), especially in countries with insufficient forest resources (Cappelletto et al., 2000).

Using agricultural remains and the residues of weed plants can help to meet the rising need of paper in the packaging industry as well as health and hygiene items like towel of paper, toilet paper, and disposable wipes of makeup (Adel et al., 2016; Mousavi et al., 2013). Non-wood raw materials serve as a key fiber resource in regions with limited forest resources. Using plant fibers that are not wood, such as bagasse, rice straws, corn stalks, and cotton stalks, can help increase the amount of raw materials that are available for manufacturing paper. Wood accounts for around 90% of the total production of chemical and mechanical pulps around the globe, whereas less than 10% of paper and pulp are produced from raw materials of non-wood (El-Sakhawy et al., 1996). Approximately 18% of bagasse, 44% of straw, 13% of bamboo, 14% of reeds and 11% of other resources make up non-wood pulp. The two main nations where non-wood pulp is produced in large quantities are China and India (Oinonen and Koskivirta, 1999). China alone produces 70% of the world non wood pulp production.

In countries like China, India, and Egypt where there are little forest resources, a wide variety of non-wood plant fibers are vital as fiber supplies and are gradually becoming more significant in these locations (Laftah and Rahman, 2016). Therefore, the future fiber shortage that is anticipated could be resolved with use of non-wood resources. The utilization of forest resources in a variety of businesses, including the production of paper, building and furniture, has significantly increased in recent years. Fibrous wood is used extensively in the paper and pulp sector. There are significant environmental problems linked to this strong reliance on fibrous wood including: forest destruction, emission of GHGs and rise in global temperature (Ashrafi et al., 2015). Due to this increasing global demand for raw materials of fibers, the shortage of plants in numerous countries and the increasing awareness of sustainability, agricultural crop residues (non-wood) have emerged as one of the great significant alternative resources (Bhardwaj et al., 2019; Gharehkhani et al., 2017). Currently, the utilization of these residues is not a wise practice since they are often burned in open land with inadequate control measures, leading to severe environmental consequences due to generation of heavy smog (Kong et al., 2012). Because these wastes are sustainable and reasonably priced sources of cellulosic fiber, they could provide a competitive alternative to woody lignocellulose biomass if used properly. Their remnants show structural resemblances to other plant fibers used in paper manufacturing with similar composition and physical and chemical properties (Jiménez et al., 2005).

Types of fibers of non-wood for pulp and paper production

Three categories of lignocellulosic fibers are commonly used in the manufacturing of pulp and paper: Recycled fibers, non-wood, and wood. Non-wood was the word created to distinguish it from hardwoods and softwoods, the two main sources of wood fiber. Based on the kind of pulp to be made, non-wood plant fibers have been divided into two general categories: Specialty fibers (softwood substitutes) like flax, sisal, kenaf, bast fibers, hemp, bamboo, abaca, and Common non-wood fibers like cereal straws, grasses, bagasse, bamboo, and reed sand (Hurter and Eng, 2002). The potential sources of non-wood fibers for the production of paper have been categorized into three distinct groups: (1) crop residues derived from point source processing centers, (2) residues from food crops, and (3) crops cultivated solely for their fiber content (Rowell and Cook, 1998).

Among the three general sources of raw material, wood fibers from trees remain dominant of others two. The paper manufactured from any of the three clusters mentioned above retains its fabric-like nature, formed by dewatering a semiliquid comprising cellulosic fibers. In essence, this procedure includes the lignin of slurry and, often, hemicellulose being removed. The processing stages in papermaking based on type of raw material are illustrated in Figure 1 (Yadav et al., 2020).

 

Advantages of non-wood

The utilization of non-wood resources in the production of pulp offers advantages like easy pulping, the provision of exceptional fibers suitable for specific paper types and the creation of high-quality bleached pulp. In farms, a variety of non-wood fibers from annual plants can be produced and collected annually with large yields of up to 3–18 tonnes per hectare (Saijonkari-Pahkala, 2001). In comparison to wood species, non-wood species used in papermaking have a rapid growth rate, resulting in quicker returns to the cultivators. The greatest advantage of incorporating agricultural residues like straw, bagasse, corn stalks and cotton stalks in mills of pulp is twofold. Firstly, it facilitates the efficient disposal of waste materials before harvesting of new crops. Secondly, farmers can earn additional income through this utilization process.

By utilizing these resources, it becomes possible to produce high-quality bleached pulp through a less polluting process compared to hardwood pulp (Johnson, 1999) and with less requirement of energy (Rezayati-Charani et al., 2006). Along with other many countries across the globe, Pakistan has also fewer forest cover thus, the utilization of non-wood fibers can be served as a viable alternative to the continuously depleting forest wood resources (Jiménez et al., 2007). Therefore, it is clear that establishing new local sources of pulping and raw materials in Pakistan would not only result in lower imports but also provide financial incentives to the industrial and agricultural sectors of the country with less environmental and energy burden.

Challenges of non-wood

The utilization of agricultural residues presents some challenges which are not easy to handle. A significant obstacle in introducing fibers of non-wood into the paper sector and industry is the logistics requirement for collection. The cultivation of non-wood sources occurs in dispersed locations, making the collection of raw materials challenging. Consequently, pulp mills utilizing non-wood materials must be kept relatively small to minimize the transportation expenses associated with collecting these raw materials. Non-wood paper mills, as typically operating on a smaller scale, often face financial constraints that prevent them from investing in a proper recovery system. As a result, these mills release their effluents directly into the environment.

An additional difficulty associated with non-wood plant materials is that their chemical composition and morphology are subject to vary with harvesting seasons due to factors including harvesting or cutting time, geographical place and plant breeding (Young, 1997). Moreover, Ash and silica content are normally higher in non-wood fibrous material (Hurter, 1988). The majority of silica tends to dissolve during the alkaline cooking process which later contributes to various issues within the chemical recovery procedure. It results in reduced effectiveness of certain equipment, heightened viscosity of the black liquor and blockage of tubes; posing challenges in pumping the liquor to specific segments of the retrieval process. These issues make the process of chemical recovery challenging, costly and less effective in comparison to the black liquor recovery from wood (Moore, 1996). Moreover, non-wood fiber material retains water more slowly than woody material does, which complicates the processes of washing, screening and paper machine operation.

Reasons for utilizing fibers of non-wood in pulp and paper sector of Pakistan

Quickly expanding paper sector

The population and economic growth of Pakistan have led to an increase in need for paper and paperboard products. With a total installed capacity of 1,050,499 metric tons annually, the paper industry of Pakistan is made up of more than 57 pulp and paper factories. Most of the raw material for the production is imported from different countries. This import can be reduced by utilizing the agriculture residue which is abundantly found in Pakistan.

Shortage of wood fiber

In Pakistan, using non-wood plant fibers to produce pulp and paper is not an option it is a need. Because this country is not rich in forest resources. Only 4.8% of Pakistan’s total land area is covered by forest which indicates a lack of forest resources appropriate for pulp manufacturing. Because of the growing need for wood fibers in the pulp and wood industries, this shortage becomes even more severe. So, the virgin wood has an important role in fulfilling the demand of forest products. However, several parts of Pakistan have limited forested areas, making the availability of non-wood fibers for the production of pulp and paper necessary rather than optional.

Special papermaking properties of selected non-wood fibers

Certain non-wood plant fibers are in demand due to their unique properties which make them superior to wood fibers, especially for specialty paper production. The applications of Bagasse pulp are found in a wide array of paper types such as bag, wrapping, printing, writing, toilet tissue, toweling, glassine, corrugating medium, liner board, bleached boards and coating base stocks (Atchison, 1993). Premium letterhead paper, currency paper, dissolving pulp and several more specialty products can all be made with cotton linters (ATEŞ et al., 2015). Hardwood chemical pulp for writing and printing can be substituted from Bagasse and straw due to their excellent formation to paper (ATEŞ et al., 2015; El-Sakhawy et al., 2018). Wheat straw has shown a good indication in the proper supply for writing and printing paper (Kaur et al., 2018). Pulps formed from non-woody annual plants, such flax, kenaf, bagasse and rice and wheat straw can function well as reinforcing fibers in pulps derived from waste paper.

Non-wood fibers availability

Agriculture residue is available locally at a very low price or even free of cost but the main cost associated with it, is the cost of transportation and collection. Due to huge amount of agriculture wastes, it is not easy to handle. Also due to its manual collection, it acquires huge labor cost ratio to the raw material cost. Therefore, the countries with lowest labor wages, the use of these raw material can be extremely suitable in pulp manufacturing as compare to wood pulping (Gominho et al., 2018).

Over view of agriculture sector of Pakistan

The agricultural sector of Pakistan plays a vital role in its economy. Its contribution to the total GDP is 22% and the total workforce absorbed is 42%. Year-wise Agriculture Contribution and Labor Employed in Agriculture Sector of Pakistan is illustrated in Figure 2 (Possible usses of crop residue for energy generation instead of open burning, December, 2019).

 

Pakistan accounts 40.2 % Agriculture land of its total land. The agriculture land distribution by crops illustrated in Figure 3 shows that sugar cane is the highest crop produced as compare to other crops in Pakistan which is 63% of the total crop production (Possible usses of crop residue for energy generation instead of open burning, December, 2019).

 

Pakistan has a potential of cultivation of major crops including wheat, maize, rice, sugarcane and cotton etc. The annual production of major crops of Pakistan and their generated residues are tabulated in Table 1 (Possible usses of crop residue for energy generation instead of open burning, December, 2019).

 

Table 1: Crop residue potential in 2017-18 in Pakistan.

Crop	Annual production (000 Tons)	Gross residue generated (000 Tons)	Surplus residue potential (000 Tons)
Wheat	25,490	45,882	10,294
Rice	10,320	17,544	4,912
Maize	5,700	13,110	3,278
Coarse cereals	504	907	200
Cotton	1,935	7,353	4,559
Sugarcane	81,102	32,441	12,652
Pulses	125	250	95
Oilseeds	3,555	5,333	1,600
Total	128,731	122,820	37,389

 

Agriculture residues characterization

In comparison of wood fibers, non-wood fibers have vided range of physicochemical properties. Other than having a higher quantity of hemicellulose, silica, and nutrients than wood, non-wood fibers possess certain crucial physical characteristics such as low bulk density, high fiber content and short fiber length. For instance, sugar cane has 74% holocellulose and roughly 45% cellulose by dry matter, compared to 45% of hardwood fibers (Peng and Sirnonson, 1991). Other materials that are frequently used in the manufacturing of writing and printing paper include rye, kenaf, hemp, jute, and reed (Ashori, 2006). The fiber morphology of commonly used agricultural fiber-rich materials and their chemical characterization are shown in Tables 2 and 3, respectively.

 

Table 2: Fiber characteristics of some important agriculture residue.

Agriculture residue	Wall thickness (µm)	Lumen diameter (µm)	Fiber width (µm)	Fiber length (mm)	Reference
Sugarcane bagasse	5.63	9.72	20.96	1.59	(Samariha and Khakifirooz, 2011)
Banana fiber	5.2	29.4	41.6	2.84	(Ogunsile and Oladeji, 2016)
Barley straw	4.07	6.97	15.26	0.67	(Tsalagkas et al., 2021)
Canola straw	7.43	11.9	28	1.21	(Yousefi, 2009)
Coconut husk/coir fibers	2.91–4.02	10.71–12.97	17.52–20.68	0.69–1.06	(van Dam et al., 2006)
Coconut husk/coir fibers	4.41	13.59	20.09	0.84	(Main et al., 2014)
Coconut husk/coir fibers	3.3	10.71	17.6	0.67	(Tsalagkas et al., 2021)
Sunflower stalk	5.85	11.12	22.84	0.96	(Kiaei et al., 2010)
Sunflower stalk	5.9	11.9	23.7	0.96	(Rudi et al., 2016)
Kenaf bark	4.2	11.9	21.9	2.32	(Ververis et al., 2004)
Kenaf fiber (core)	4.3	13.2	22.2	0.74	(Thiruchitrambalam et al., 2012)
Maize stalks	2	4.4	8.4	1.52	(Garay et al., 2009)
Maize stalks	4.19	10.92	20.12	0.88	(Kiaei et al., 2010)
Maize stalks	8.82	13.67	30.19	1.52	(Ekhuemelo and Tor, 2013)
Maize Husk	8.82	13.67	30.19	1.37	(Ekhuemelo and Tor, 2013)
Maize straw	3.68	9.73	17.18	0.75	(Tsalagkas et al., 2021)
Miscanthusgiganteus stalks	4.64	5.76	15.17	0.5	(Tsalagkas et al., 2021)
Rapeseed straw	1.17	23.02	12.5	5.26	(Enayati et al., 2009)
Rapeseed straw	4.31	15.5	24.12	0.95	(Kiaei et al., 2010)
Rapeseed straw	2.25	8.6	13.1	1.2	(Tofanica et al., 2011)
Rapeseed straw	4.91	19.1	28	1.03	(Tofanica et al., 2011)
Rapeseed up	4.25	9.73	18.36	0.71	(Tsalagkas et al., 2021)
Rapeseed low	3.86	11.04	18.99	0.57	(Tsalagkas et al., 2021)
Rice straw	3.02	4.52	10.77	0.54	(Tsalagkas et al., 2021)
Rice straw	1.5	1.9	4.9	0.66	(Garay et al., 2009)
Rice straw	3.16	4.57	10.89	0.83	(Kiaei et al., 2010)
Rice straw	1.83	5.6	11.6	0.78	(Ferdous et al., 2021)
Sugarcane	NA	NA	19.35–20.96	1.22–1.59	(Hemmasi et al., 2011)
Sugarcane bagasse	4.5	10.25	19.86	1.15	(Tsalagkas et al., 2021)
Sugarcane bagasse	1.6	5.2	8.4	1.7	(Khristova et al., 2006)
Sugarcane bagasse	7.74	6.27	21.4	1.51	(Agnihotri et al., 2010)
Sugarcane bagasse	5.64	9.72	20.96	1.59	(Hemmasi et al., 2011)
Sunflower stalk	4.8	13.23	22.99	0.64	(Tsalagkas et al., 2021)
Wheat straw	4.59	4.02	13.2	0.74	(Deniz et al., 2004)
Wheat straw	4.13	8.34	16.87	0.78	(Tsalagkas et al., 2021)
Wheat straw	1.6	6.8	9.9	0.85	(Garay et al., 2009)

 

Table 3: Proximate chemical analysis of some important agriculture residue.

Agriculture residue	Holoce Llulose (%)	Klason lignin (%)	Hot water solubility (%)	Cold water solubility (%)	Alcohol benzene solubility (%)	1 % NaOH solubility (%)	Ash (%)	References
Barley straw	66.01	19.47	16.25	11.01	8.71	56.25	11	(ATEŞ et al., 2015)
Cornstalk	69.92	18.16	16.82	14.64	8.57	46.43	7.75	(ATEŞ et al., 2015)
Cotton stalk	62.79	23.79	17.91	15.05	8.36	48.88	4.99	(ATEŞ et al., 2015)
Hemp	86.08	6.42	5.85	5.29	1.59	20.04	3.62	(ATEŞ et al., 2015)
Cornstalk	82.1	7.3	12.6	NA	NA	69.6	24.9	(Daud et al., 2016)
Empty fruit	80	17	3.5	NA	2.3	NA	3.5	(Khalil, 2011)
Oil palm	83	21	4.5	NA	2.3	NA	2.5	(Khalil, 2011)
Oil palm	73	25	5.5	NA	1.3	NA	2.5	(Khalil, 2011)
Reed stalk	78.85	22.79	9.8	7.61	3.26	36.81	4.17	(ATEŞ et al., 2015)
Rice straw	60.7	12–16	7.3	9.66	0.6	57.7	15–20	(ATEŞ et al., 2015)
Rye straw	76.95	17.25	15.72	11.95	7.44	44.35	4.01	(ATEŞ et al., 2015)
Sunflower	66.85	14.43	24.26	21.08	7.48	50.05	7.99	(ATEŞ et al., 2015)
Tobacco stalk	64.29	15.15	21.56	17.15	8.06	50.57	14.4	(ATEŞ et al., 2015)
Wheat straw	69.84	22.33	14.71	11.33	9.33	53.67	11.6	(ATEŞ et al., 2015)

 

Pulping processes of non-wood

Pulping is actually the separation of fibers by dissolving lignin content among them using mechanical, chemical or both methods (Tian et al., 2019). Mechanical Pulping uses mechanical energy for fiber separation from one another, causing sluggish disturbance in the connectivity of fiber, discharging fiber bundles, single fibers and fiber fragments (Sandberg et al., 2020). On the other hand, chemical pulping use chemicals that make the lignin water-soluble by breaking down its bond in order to get the separated fibers. Due to its capacity to preserve the biomass of the fibers and improve undried fibers conformability and flexibility, chemical pulping is typically chosen over other pulping techniques (Fearon et al., 2020).

For pulping agricultural residue, the most world widely used chemical pulping method is soda pulping in the paper manufacturing sector. For a short interval of time, this process involves the use of chemicals, such as Na2CO3 (6 to 8% solution) or a combination of Na2CO3 (50 to 85% solution) and NaOH (15 to 50% solution), as well as high temperatures and high steam pressures (Jiménez et al., 2005).

Advantages of soda pulping include reduced cooking time, pulp free of sulfates and good chemical recovery. Anthraquinone can be added to pulp to improve the strength and quality of the paper (Jiménez et al., 2009).

Conclusions and Recommendations

Non-wood pulp technology and raw materials may soon gain prominence in the paper manufacturing sector because of the imported pulp huge cost and wood resources scarcity in emerging nations like Pakistan. The heavy reliance of pulp and paper sector on wood causes serious environmental problems such greenhouse gas emissions, deforestation, global warming and the loss of fibrous wood resources. Because of these issues, the paper-based sectors in developing countries now depend heavily on other raw materials. Due to environmental and economic concerns, the pulping of agricultural leftovers has attracted increasing interest. Numerous conclusions have been drawn over time from extensive research and investigations in the subject of pulping of non-wood. As such, worries regarding non-wood fibers utilization in the manufacturing of paper have decreased in comparison to prior years. However, there are still a lot of issues facing the non-wood paper sector.

Pakistan has an abundance of agricultural residue, with wheat accounting for the most (45.88 MT), followed annually by sugarcane bagasse (32.44 MT), rice (17.54 MT) and maize (13.11 MT). As a result, Pakistan has access to enough high-quality non-wood raw materials for pulping. Furthermore, the widespread availability of straws makes it a cheap and appealing raw material for papermaking in Pakistan. Combining non-wood materials with other wood pulps has the potential to produce pulp of a higher quality while also protecting Pakistan forests and financial resources.

Acknowledgment

I would like to express my sincere gratitude to Director Forest Products Research Division, Pakistan Forest Institute Peshawar and the coauthors for their guidance, assistance and contribution provided throughout this study.

Novelty Statement

This study presents a novel approach to producing pulp and paper in Pakistan by using non-wood fibers, such as agricultural leftovers. It provides a sustainable substitute that might drastically cut down on deforestation and other negative environmental effects while also bringing down manufacturing costs.

Author’s Contribution

Abdur Rehman: Contributed in Collection of data of review manuscript and composition of it. Handled the visualization of data and results.

Mansoor Ali Khan: Contributed in composition of review manuscripts and paraphrasing the literature data.

Abdur Rahman Khan: Contributed in reviewing and editing the manuscript to refine its clarity and accuracy.

Sajid Ali: Contributed in collecting and tabulating the data and proof reading of review manuscript.

Zeeshan Ahmad: Contributed to the conceptualization of the study and the development of the research methodology. Also contributed to the critical review and editing of the manuscript.

Conflict of interest

The authors have declared no conflict of interest.

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