Currently, the paper industry is one of the key industries in our country. It applied to common items such as notebooks, books, newspapers, or environmentally friendly products. With the development speed above, waste control in the paper production process is a challenge for managers. And sewage sludge is one of them because if we do not manage it closely, it will cause a waste of resources. Moreover, it causes environmental pollution, and the residence of disease vectors such as flies, mosquitoes, etc. So what are the characteristics of sewage sludge? And how is an effective treatment? Let’s follow BioFix Fresh to follow the article below.
1. Characteristics of waste sludge from the pulp and paper industry
In solving the processing of raw materials, paper and pulp wastewater will generate a large amount of solid waste along with impurities of various properties. Therefore, the paper waste sludge will have some of the main components as follows:
Water accounts for 60-65%, the rest is cellulose, hemicellulose, lignin, extractant, ash… In which:
Ash content in paper waste sludge depends on the input materials of the pulp such as hardwood, softwood, bamboo, cork, etc. It is measured by the content of inorganic substances other than carbon, hydrogen, oxygen, nitrogen, and function. This amount ranges from 0.3 to 1.5%, depending on the plant’s variety, age, and growth.
During flocculation, a regulator (polymer) is formed in the sludge when it is removed from the water, through a floating gland tank. Polymers used as coagulants in water treatment include cationic, neutral anionic molecules…
In addition, the paper sludge has a mixture of short cellulose fibers and inorganic fillers such as calcium carbonate, kaolin, chemicals left in the sludge, etc. Therefore, the sludge is discharged into the environment, leading to pollution.
2. Types of sludge
In different stages, there are several types of sludge:
• Primary sludge: formed from the production of primitive wood pulp.
• De-inking sludge: recovered from the de-inking process of recycled paper.
• Secondary sludge: recovered from recycling wastewater treatment.
The total amount of pulp-containing sludge ranges from 3 to 5% of paper production. Cellulose content can account for 40-60% of the solid mass.
3. Recirculation of paper waste sludge
a) Use of sludge in composting
Because fertilizer made from waste paper sludge, it will go through many different stages, creating many intermediate products with biological transformations. Thereby, creating a pathogen-free, useful, safe, and beneficial end product for plant growth, based on the temperature variation occurring during the aerobic incubation period, mainly at the thermophilic phase.
This is the stage of the highest temperature, from 40-65oC to kill pathogenic microorganisms and stabilize waste products. Moreover, promoting the breakdown of proteins, fats, and complex hydrocarbons such as cellulose, hemicellulose, etc.
In addition, we can add BioFix Composting to promote the composting process and improve the quality of the finished product. With ingredients of selected microbial strains, the above preparation is safe for humans and environmentally friendly.
b) As fuel for building materials
Besides, paper sludge can also be used to make products in the field of building materials production, specifically: bricks and cement from 5 to 15% of paper sludge are added as raw materials. The product has become lighter, saving the heating time, and the fuel in the kiln. Increases resistance to cracking during drying and firing with its inherent fiber content. In addition, paper waste sludge can also become an effective alternative fuel in Portland cement production, due to its high organic content.