Investigating the Use of Eco-Friendly Biosolids Made by Recycling Different Wastes in Papermaking

Shuenn Yih Kuo^*
*Correspondence: Shuenn Yih Kuo, Department of Architecture, National Cheng Kung University, 701 No. 1, East District, Tainan 701401, Taiwan, Email:

Keywords

Alkali-activated binder • Wastes in papermaking • Blast furnace slag • Compressive strength • Flexibility • Texture

Introduction

The COVID-19 epidemic has caused the global output of paper products, which reached 90.2 million tonnes in 2021, to keep increasing. The disposal of trash from the paper sector and related costs total over 3 billion USD annually. The price is over $7 million USD for a medium-sized mill. Numerous solid wastes, including chips from wood processing, lime muds from kraft pumping, bottom ash in the recovery boiler, and paper sludge from on-site sewage treatment, are generated during the papermaking process. For the management of these wastes, several programmes have been created [1]. Examples of biomass materials that could be used as fuel in paper mill boilers include wood chips and water treatment sludge. But this procedure` providing electricity for the paper-making process resulted in increased air and water pollution. Other solid wastes, like lime sludge, were challenging to turn into fuel. The ashes from incineration were typically landfilled with these materials, resulting in the occupation of the waste plant and the possibility of soil and water contamination. Determining appropriate resource-based solutions to reprocess these wastes without adding to or shifting the environmental load is thus important [2].

Discussion

The experimental raw material with the label S6000, packaged in 20 kg sealed bags, and given by China Steel in Taiwan, was the BFS used in this investigation. The Chung Hwa Paper Corporation in eastern Taiwan contributed the papermaking byproducts. Among these, lime mud from the caustic kiln, paper sludge from the sewage treatment process, and bottom ash from the recovery boilers were all gathered. The same batch of paper was used to collect all the papermaking byproducts, with 150 kg samples of each item being placed in six airtight bags. Sodium silicate powder was utilised to prepare activators due to the ease of storage and transportation, as well as the simplification of the creation of alkali-activated cementitious materials. The ratio of SiO2 to Na2O in sodium silicate powder was 46.07% to 51.35%. The silicate modulus (Ms) of the activators was 0.93, the water-binder ratio (W/B) was 0.5, and the activators' AE was 10% [3].

The manufacture of the activator or material mixture, the creation of the slurry, the casting of specimens, and the testing were all included in the experimental methods. The alkali activator solution was first made by combining water and sodium silicate powder, and then it was sealed and allowed to cool to room temperature. The necessary amount of raw materials was weighed in the meantime, and they were thoroughly combined for 1 minute. The combination of dry materials was then finished the slurry by adding to an alkali activator and mixing for an additional 10 minutes. The specimens for compressive strength tests were cast in 50 mm 50 mm 50 mm moulds with two layers of mortar, then compacted and vibrated to remove air bubbles, in accordance with ASTM C109 [4].

To stop moisture loss after the initial setting, specimens were covered in plastic films. After 24 hours of casting, samples in this investigation were demolded and kept in a control box at 20 °C and 95% relative humidity. Three samples from each experimental series were evaluated individually for compressive strengths at 3, 7, and 28 days, taking into account the experimental design and sample size. The stress-time curves at day 28 were recorded. 50 kilogramme of sample six sealed sachets of each substance are contained six sealed sachets of each substance are contained. The stress-time curve of the BFS with 20% of the waste replaced was chosen as the study object with the optimization of compressive strength in mind. depicts the stress-time curves for partial replacement of BFS with lime mud or bottom ash, which demonstrated the properties of brittle materials.

Additionally, the curves had comparable forms, with a linear rise in yield strength and a steep falloff at the apex. According to this fluctuation, the samples were crushed and the peak stress intensity was lost. Only the peak points of the curves varied between them, showing that neither lime mud nor bottom ash could alter the properties of brittle materials to cause BFS to be activated by alkali. In the partial replacement of paper with BFS Sludge or wood chips, the curves at the peak steadily declined. This modification showed that the samples still occasionally surpassed the yield strength. These findings suggest that adding wood chips or paper sludge to alkaliactivated BFS could considerably alter its brittleness into ductility [5].

Conclusion

This study assessed the mechanical characteristics, flexibility, and sample texture of several papermaking wastes that might be alkali-activated and used as cementitious materials. The findings increased our understanding of recycling paper waste and illustrated some potential benefits of employing papermaking wastes as building materials (e.g., toughness enhancement and wood texture). A reference for the actual transformation of wastes in papermaking can also be drawn from some experimental data (e.g., 6% AE, 20% waste addition). The contents of papermaking wastes from various sources vary greatly, hence the generalizability of the experimental results is limited.

Acknowledgement

None.

Conflict of Interest

None.

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