Haile et al. Bioresour. Bioprocess.
(2021) 8:35
Page 7 of 22
Among different factors that affect the identity and amount of generated waste from pulp and paper, mills is the type of manufacturing process amplified with the wastewater treatment technologies adopted. The pulp and paper mill waste mainly includes rejects at different stages such as woody and barky residues and sand par- ticles, black liquor, and wastewater sludges. Inorganic sludges are isolated from the chemical recovery station and are composed mainly of calcite lime mud, the slacker grits, and green liquor dregs (Bird and Talberth 2008; Environmental 2007; Leponiemi 2008). The sources of wastewater treatment residues as part of potential sludge are conveyed from two sources. The major part is the primary sludge from the entire manu- facturing route and those generated from the second- ary clarifier are categorized as biological sludge (Simão et al. 2019). Also, the sludge from the water treatment is regarded as chemical flocculation sludge. Deinking sludge from recycled paper production which contains mainly tiny fibers or fragmented fines and additives is another source of waste (Simão et al. 2018). The major source of waste from different stages of pulp and paper manufacturing is summarized in Table 3. The regions and different recycling processes and allied recycling rates determine the quantity of biomass gener- ated from paper production. The variation within regions
Availability of by-products from pulp and paper mill A global review of manufacturing sectors divulged that 17% of the total global waste comes from paper indus- tries (Fig. 5) (Karak et al. 2012; Sakai et al. 1996). Pulp and paper mills contribute to air, water, and land pol- lution and discarded paper and paperboard make up roughly 26% of solid municipal waste in landfill sites (Pati et al. 2008; Ritchlin 2012). Waste data based on relative waste analysis from a specific global company revealed the large contribution of pulp and paper mill waste to the total solid waste indicative of a need to set up a platform for strategic intervention for the realiza- tion of a green environment (Mladenov and Pelovski 2010; Ince et al. 2011). The study reveals that from a total solid waste generation of 238,771 thousand tonnes, around 186 thousand tonnes is generated from pulp and paper industries. Different types of solid wastes and sludge are gener- ated in the pulp and paper mills at different sites of the process (Fig. 4). Potential wastes are generated from wood preparation and the actual pulp manufactur- ing and paper-making stages. Furthermore, an ample amount of different types of wastes are generated from chemical recovery, effluent treatment, and paper manu- facturing methods that utilize recycled paper routes (Camberato et al. 2006; Akbari et al. 2018).
Fig. 4 Sites of waste generation in pulp and paper manufacturing
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