Haile et al. Bioresour. Bioprocess.
(2021) 8:35
Page 13 of 22
waste types. The lower yield of biomaterial ingredients from selected biomass can be enhanced by the integra- tion of pulp and paper industries especially in develop- ing countries like Ethiopia. Another challenge which is still prominent in developing countries is the availability of suitable and integrated waste to energy and related biorefinery system (Ismail and Nizami, 2016; Diep et al. 2012). This directly affects the mass production of high valued-added materials from pulp and paper industry biomass. The other potential challenge is the adequacy of labor in terms of skill as the production of the high value- added biomaterials requires stringent control allied with health and environmental safety concerns and regula- tions. There are also specific challenges in terms of each high-value-added biomaterial addressed in the review. These challenges need critical investigation and can be amended with versatile possibilities as far as continuous marketability of the biomaterials and their high value- added application is targeted. Beneficiation of black liquor for high value-added materials High-performance carbon fiber from black liquor lignin There is an estimated 70 million tonnes of lignin from pulping processes worldwide (Dessbesell et al. 2020; Bajwa et al. 2019). Structurally lignin is a heterogeneous aromatic polymer and consists of mainly three precur- sors: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol (Fig. 8) (Chen 2012). It is a natural macromolecu- lar with multiple aromatic ring compounds consisting of hydrophobic non-polar substructures of phenyl propane and polar groups like carboxyl.
black liquor, woody residues including sawdust, sludges of different types, and fly ash. An abundant quantity of the mill wastes is disposed to landfill, and some are incinerated. Instead using an appropriate biorefinery approach, it is possible to extract different ingredients from the biomass for versatile utili- zation as a biomaterial in different fields of applications. Through the biorefinery approach environmental pol- lution is reduced or eliminated, product substitution is enhanced. Furthermore, the allied spinoff company for biomaterials and the industrial-scale prospect will boost the economic growth. The potential ingredients of cur- rent concern from the biomass are identified (Table 7). Based on the characteristics of ingredients in each bio- mass potential beneficiation routes are proposed for high value-added materials (Simão et al. 2018; Rajput et al. 2012). The general challenges with regards to the forecasted application of pulp and paper industry wastes as high value-added materials can be broadly classified into three patterns. One major challenge is the lower yield from each biomass in terms of the continuous supply of certain
Table 7 Potential ingredients available from pulp and paper mill waste S. N Type of waste Potential ingredients
1 2 3 4
Black liquor
Lignin, xylan
Sawdust /woody residues
Cellulose Cellulose Minerals
Sludges Fly ash
Fig. 8 Major precursors of lignin ( a ) typical structural model of lignin ( b )
Made with FlippingBook Online newsletter maker