Black Liquor Waste Management in the Pulp and Paper Industry

Inhaltsverzeichnis

1. Frontmatter

2. Black Liquor: Chemical, Physical and Combustion Properties and Their Importance in Chemical Recovery Operations

   B. P. Thapliyal, A. K. Dixit

   Abstract

   Black liquor is an invaluable resource for paper mills, processed through various unit operations in the chemical recovery systems to recover and recycle pulping chemicals, and efficiently generate steam and electrical power. During its processing in the chemical recovery systems, black liquor undergoes four major unit operations: concentration, combustion, causticization, and calcination. These operations present significant challenges to mills, requiring careful black liquor management to ensure efficient chemical recovery and energy generation. The properties of black liquor are crucial in understanding the key characteristics that affect the operations of chemical recovery systems. These properties depend on various factors such as raw materials and cooking conditions, including chemical charge, time, temperature, and pressure. Analysis of black liquor properties helps to reveal its nature and aids plant managers and engineers in operating chemical recovery processes smoothly and efficiently. Black liquor properties can be categorized into three main subcategories: chemical, physical and rheological and combustion properties. Since the chemical recovery unit operations in mills differ in their level of operation, equipment design, automation, and controls, therefore, a better understanding of black liquor properties supports to understand their impact in efficient operation of processes. Thus, insight in the black liquor properties becomes crucial for process engineers and operators to recognize their intricate relationships with processes, allowing them to strike an optimal balance for efficient operation of chemical recovery systems.

3. Potential of Synthesis of Polyurethane Foam from Black Liquor

   Saakshy, Reena Choudhary, Rahul Mishra

   Abstract

   Lignin has found its diverse applications and one of the potential utility studied was for making polyurethane foam. Polyurethane is a versatile polymer that belongs to the class of “synthetic polymers known as polyurethanes”. It is formed through the reaction of “polyols and diisocyanates”. The reaction between these two components forms “urethane linkages”, which are responsible for the polymer structure. The addition of lignin to polyurethane foams improves the mechanical and protective properties, making them suitable for use in construction, automotive and other industries. In the scope of this chapter, the utilization of lignin in manufacturing polyurethane foam and the effect of properties of polyurethane foam has been covered. Polyurethane foams are important products for the production of polyurethanes, such as hard, semi-rigid and soft foam types. Rigid foams are chiefly employed in furniture, coatings, adhesives and other applications. Flexible and semi flexible foams are extensively used in the automotive sector for seating cushions, bumpers and sound proofing properties. Rigid polyurethane foam with lignin addition provides high insulation and mechanical properties for the building, automotive industry, freeze industry, and naval applications with improved moisture and flame resistivity.

4. Trends in Analytical Techniques for Lignin Quantification and Characterization

   Saakshy, Rahul Mishra

   Abstract

   Lignin is another most abundantly available organic compound/biopolymer after cellulose and greatest source of natural aromatic compounds on earth. Lignin comes under the category of organic polymer and play an important role in the formation of “cell walls” in wood and lend “rigidity to the cell walls”. In the “pulp and paper sector”, lignin is present in the “black liquor” which is received after the pulping or delignification process. There is increasing need of extraction, purification and characterization of the lignin to explore its application in various industries. The analytical techniques of lignin is important and therefore, the quantitative and qualitative analytical methods of lignin is required to be explored for better utilization of lignin in various industrial applications. In the scope of this chapter, the details of analytical techniques of lignin has been mentioned including the characterization of chemical structure, particle size and molecular size determination.

5. Modification of Black Liquor Properties to Enhance the Chemical Recovery Efficiency

   A. K. Dixit, B. P. Thapliyal

   Abstract

   The black liquors generated from different raw materials have different ratios of organic to inorganic constituents, varying concentrations of process and non-process elements, widely ranging viscosities, and thermal properties. These situations can result in inefficient operations of chemical recovery systems, and over a long period can lead to terrible situations with the build-up of many problems in almost all unit operations. Modification of black liquor properties by subjecting it to controlled chemical, mechanical, and thermal treatments is one of the solutions to make black liquors suitable for smooth operation in chemical recovery unit operations. The agro residue and bamboo based black liquors are generally difficult to handle. Bagasse, wheat straw, rice straw and bamboo black liquors have some unusual characteristics of high viscosity and scaling during evaporation in multiple effect evaporators. As a result, they pose problems in subsequent recovery operations like combustion in recovery boiler, clarification of white liquor and reburning of lime sludge in lime kiln. Firing of low solids black liquor due to highly viscous semi-concentrated black liquor, significantly affects the thermal efficiency of recovery boilers and results in uneconomical operation. Silica present in straw and bamboo black liquors causes problems in smooth evaporation in multiple effect evaporators (MEEs), due to poor heat transfer and equipment down time. Liquor heat treatment and desilication of black liquor are discussed in this chapter to address these problems by modifying black liquor properties after subjecting liquors to chemical and thermal treatments. The impact of modification of black liquor properties is evident on operation of various other chemical recovery processes.

6. Development of Modern Materials from Lignosulphonates

   Saakshy, Rahul Mishra

   Abstract

   The end use of lignin is dependent on the structure which in turn is affected by the raw material and the pulping method or the extraction process. Lignosulphonates are organic polymers extracted from the black liquor of sulphite pulping process. In this chapter, the detailed utilization of ligno-sulphonates has been mentioned including dust control, lubricants, antioxidants, fire retardants, ceramics, chelating agents, binders, emulsifiers, fillers, dispersants, sodium ion batteries, cathode for lithium ion batteries, lead acid battery, carbon fibre, fertilizers, adhesives, enhancer of thermal behavior, animal species and construction material. The development of modern materials from lignosulphonates reduces the dependency on petroleum based materials and open avenues for greener options utilizing renewable resources from lignosulphonates.

7. Recent Advances in Chemical Recovery Furnace for the Efficient Combustion of Black Liquor

   Jaykumar Bhasarkar, Suraj Gawade, Prasad Patil

   Abstract

   The main aim of this chapter is to give insight into the recovery furnace. In recent times, the recovery furnace is not only used to recover the cooking chemicals in the paper industry but also generate the energy in terms of electricity. In modern days, the demands of the electricity consumptions increase and therefore in order to cater these demand, the new modern recovery furnace need to be developed. In this chapter, we have discussed the early recovery furnace and their development in various functions. The corrosion and erosion is the major issue in any recovery furnace as the concentrated black liquor is the feedstock. Black liquor contains several organic, inorganic and non process elements and hence it is very essential to control the corrosion in the furnace by increasing the heat transfer rate. Several possible solutions have been discussed to enhance the capacity of the furnace by controlling the corrosion and erosion problems incorporated in the recovery furnace. We believe that this chapter gives more insight into the recovery furnace which further helps in the development of this research area.

8. Production of Bioethanol as a By-Product in the Pulp and Paper Industry

   Ajay Kumar Chauhan, Shailja Chauhan, Aman Singh Rajpoot, Amit Kumar Chaurasia

   Abstract

   As the world strides for renewable energy solutions, the integration of pulp and paper industries into the bioethanol production landscape emerges as a promising avenue. The pursuit of sustainable and eco-friendly alternatives have led to a paradigm shift in the biofuel landscape, with focus on leveraging the vast potential of pulp and paper industries for bioethanol production. The chapter delves into the innovative approach of utilizing lignocellulosic biomass (LCB), the primary raw material in paper production, as feedstock for bioethanol generation. By exploring the conversion of LCB into simpler sugars, researchers aim to establish a dual-purpose system, yielding both high-value paper products and bioethanol. This chapter provides a comprehensive overview of the ongoing efforts, shedding light on the key developments and challenges face towards making lignocellulosic bioethanol into commercial viable reality. Emphasizing critical role of pretreatment process hydrolysis in the production process, the chapter underscore the significance of this enzymatic or chemical breakdown of LCB as a primary key step for biofuel generation. The exploration of various hydrolysis techniques and their implications on bioethanol yield forms, a central theme, offering insights into optimizing this pivotal stage for enhanced efficiency and economic viability.

9. Valorization of Rice Straw for Ethanol Production and Lignin Recovery Through Acidic and Alkaline Pre-treatments

   Puneet Pathak, Chhavi Sharma, Sneh Gautam, Shashi Prabha Yadav, Aparajita Das

   Abstract

   Rice straw is a valuable resource that is rich in beneficial natural substances such as cellulose, hemicellulose, and lignin. These substances are commonly used in the production of biofuels and other value-added products. However, there is still a challenge in applying the biorefinery residue lignin on a large scale. The raw solid products recovered from rice straw usually contain various contaminants and heterogeneous lignin with complex molecular weight distribution. Currently, the most surplus rice straw is inefficiently burned in the field, leading to acute respiratory illnesses and dangerously high pollution levels. This is because of its limited use and low nutritional value as fodder. Therefore, new methods must be developed to use it as a feedstock for producing biofuels and biopower. Recent studies have evaluated changes in the chemical composition, physio-chemical structure, lignin-carbohydrate connections, and accessibility after several pretreatment methods, mainly acid or alkali or combined, to reduce the recalcitrance of rice straw. Utilizing every component of rice straw in a biorefinery-based method makes the process environmentally friendly and sustainable.

10. Facts on Climatic Effect of Waste Paper Recycling in the Pulp and Paper Industry

    Saakshy, Rahul Mishra

    Abstract

    The recycling of pulp and paper is said to be a key solution of mitigating environmental impact, carbon emissions and promoting sustainability. The chapter makes a review of studies conducted on aspect of recycling of paper which is said to decrease the cutting of trees and deforestation and increase ecological aspects. It has been observed in the previous studies that environment load decreases on the utilization of recycled paper. However, some studies also pointed that recycling of paper could also increase green house gas emissions if fossil fuels are used in place of renewable energy. The high energy demands of the recycling process, varied grade of recycled grades of paper and dependency on virgin raw material for specific grades of paper make the limited utilization of recyled fibre. Moreover, the energy intensive recycling process sometimes increase the carbon footprint. The recycling of pulp and paper remains a topic of study for circular economy in the pulp and paper industry. The actual climatic benefits of global recycling of pulp and paper remains limited. The holistic approach of utilization of renewable energy, improved forest policies along with recycling of paper can be an option to radically reduce the green house gas emissions in the pulp and paper sector.

11. Opportunities for Green Technology Initiatives in the Indian Paper Industry

    Rakesh Kumar Jain, Sunil Padhiyar, Saakshy

    Abstract

    Pulp and paper industry is considered among the highly resource intensive industries requiring abundant quantities of raw materials, chemicals, energy, and water. The industry continues to focus on minimizing the fresh water use and effluent discharges as a part of their move towards sustainable operating practices and closing up of the water loop. Currently, conservation and reuse of water resources have emerged as an important component of proper environmental management in the paper industry owing to the shortage of water and conflicts over water usage. The ultimate goal of the industry is to have effluent free unit operations aimed towards sustainable operation with no negative impact on process efficiency, productivity quality and environment. The traditional wastewater treatment technologies that are used in the paper mills are not able to remove recalcitrant contaminant materials; therefore, advanced wastewater treated technologies are required to either improve the wastewater biodegradability or its final quality. Thus, amid the rising water scarcity, poor internal process water quality and concern for compliance of the prescribed charter’s norms, the paper industry’s commitment to overall water conservation and management require the adoption of the innovative wastewater treatment strategies such as membrane filtration technology and combination of other options. The chapter discusses the status of Indian paper industry, issues and challenges on the water and wastewater management front with a focus on membrane filtration technology with a strategic approach including the process optimisation and appropriate membrane configuration to make it an environmental friendly and a green technological option for treatment of the paper mill effluent.