The pulp and paper industry is one of the biggest industries in the world and a growing portion of the world’s economy. According to the global paper market review 2018, the paper produced and consumed globally was approximately 406 million tons in 2017 [
1]. The share of paper and paperboard production in China has increased from 15.3% to 23.5% in five years. This was possible because of the development of the Chinese paper industry due to policymakers, researchers and international producers [
2]. India’s share in world production of paper is about 3.7%, with an estimated production of over 20 million tons per annum (2017–2018). Around 50% of this paper is used in major developed countries, with China consuming about 106 million tons. The consumption in the USDA is around 71 million tonnes, and Japan stands third, consuming 27 million tons. Paper consumption in Europe is around 92 million tonnes, whereas the developing and underdeveloped countries, such as Africa, Oceania and Latin America consume about 2% to 8% annually. The high domestic production in developing countries such as China and India cannot satisfy the demand, especially for high-grade paper, due to lack of high-quality raw material and old paper production technology being used in the industry. Therefore, such countries are importing more pulp and paper products than exporting. In the total pulp consumption of the world, the proportions of virgin fiber, recovered fiber and other fiber (non-wood) are 42, 55, and 3%, respectively [
3]. Population growth, increasing literacy rate, industrial revolution and booming e-commerce sector in developing countries are some of the key projected reasons for increase in paper and pulp demand per annum globally. With the growing industrial demand, the utilization of wood is increasing and at the same time, non-wood pulp production is also becoming crucial in the countries that do not have enough trees for pulp industry, such as China, India, Pakistan, Egypt, and Columbia. Currently, recycled waste and non-wood biomass with grasses, cereal straws, corn stalks, bamboo, and bagasse, have been found to be suitable alternatives to trees to complete our demand and supply of raw materials in a commercially viable manner. Typically, lignocellulosic biomass contains 30–50% cellulose, 20–35% hemicellulose and 15–30% lignin, which is perfectly matched for various industrial applications [
4]. Alternative fibers, such as agricultural biomass resources, have the potential to form pulp for papers thereby substituting forest wood, leading to greater sustainability, industry efficiency and lower climate impacts. Non-timber-based fibers are known to possess a variety of physical and optical properties, which can pave the way for utilizing them as a raw material in the timber dependent pulp and paper industry. Life-Cycle Assessment by tissue manufacturing giant company Kimberly-Clark inferred that, when compared between agricultural residues, softwood pulp, and transportation, the softwood-based pulp consumes the maximum use of fossil fuels for paper production and have the highest greenhouse gas emissions, and agricultural residues consume the least fossil fuels [
5].
Indian Farming, Livestock and Dung Potential
In India, 66.46% of the population reportedly resides in rural areas (World Bank, 2017), where over 15–20% of families are landless and about 83% of the landholders belong to the category of small and marginal farmers [
6]. Livestock, being a key source of supplementary income and livelihood, especially for small landholders and the landless rural poor, play an important role in the rural economy of the country [
7]. In India, the total livestock the population is approximately 600 million; where the cow and buffalo contribute 35.94% and 20.45% of the total population, respectively, and the supply of raw material (dung) is substantial [
8]. In total, 500 million tons (Mt) of gross agricultural residue is generated on an annual basis with wide regional varieties of crop-like cereals, oilseed, pulses, and sugarcane, etc. While a major portion of ruminant livestock in South-East Asia, including India, is based on such cereal crop residues, such as roots, stalks, and leaves [
9].
Bovines are typical ruminants with a four-chambered stomach, namely rumen, reticulum, omasum and abomasum [
10]. During the digestive process, the raw materials are processed mechanically in the first chamber of rumen followed by the bacterial breakdown of cellulose in the reticulum. The partially digested materials (cud) move back into the mouth and are rechewed and re-swallowed as regurgitated materials to finally break it into further finer forms. Now this enters in the other chambers, namely omasum and abomasum, where most of the moisture from the food is absorbed. In these chambers, digestive enzymes, such as lysozyme and many anaerobic microorganisms, digest the hemicellulose and pectin content of the plant fibers. It can be easily inferred that a high percentage of cellulose is undigested and excreted in cow dung [
11,
12]. Dung is one of the bioresources of this world which is available on a large scale and is still not fully exploited for its potential. In this way, ruminant animal dung may be considered as an easily available bioresource that holds great potential for sustainable development in the near future [
13]. Sustainable conversion of renewable biopolymeric feedstock in environmentally friendly products for diversity and the right applications fit well into the green growth economy [
14]. While the policy tends to focus on milk production, dung is already driving an informal economy of national importance, which was largely overlooked. Since 2016, Government of India has also been working on dung collection and its utilization under the scheme of Galvanizing Organic Bio-Agro Resources (GOBAR)-Dhan Yojana. Similarly, Cattle commission named Kamdhenu Aayog is also working on a similar approach to develop a circular economy and strengthen the livelihood through cow dung. The extraction of fibrous material from dung would add to the various uses of cow dung, such as the production of biogas, compost, etc., and keeping the organic matter for their other uses.
In the present paper, the authors have tried to explore the potential of ruminant animal dung as a sustainable and alternate source of non-wood material for the pulp and paper industry. Additionally, the morphology and physical characterization of raw fiber is studied for other applications in the future.