Feasibility of applications of waste driven composite for the treatment of paper and pulp industry wastewater

Abstract

The agro-based pulp and paper (PandP) industry produces wastewater with persistent color due to lignin derivatives and other organic compounds, which conventional treatment methods have failed to address effectively. This study explores Advanced Oxidation Processes (AOPs) for decolorizing real industrial effluents. Following circular economy principles, industrial discards such as furnace blast sand (FBS) and foundry sand (FS) were repurposed as substitutes for iron in the synthesis of Fe-TiOand#8322; composites used in the treatment process. The results highlight AOPs and material reuse as promising strategies for enhancing environmental sustainability in wastewater management. The present study aimed to reduce the residual color in real wastewater streams from an agro-based PandP industry. Wastewater samples were collected from three distinct stages: the first, known as the UASB stream, which has highest amount of color was sourced from the initial stage involving straw washing and pulping; the second, the I/L or alkali stream, was obtained from the paper-making, chemical recovery, and bleaching stages; and the third, the O/L or outlet stream, was collected after secondary treatment, though it still exhibited significant color. Due to the varying properties and color intensities of these streams, different treatment methods were employed. A two-step process combining coagulation/flocculation, followed by a simultaneous dual process of simultaneous photocatalysis and photo-Fenton, was employed to treat both the UASB and I/L streams effectively. For O/L stream direct application of dual process was successful. Coagulation-flocculation was applied as a pretreatment to reduce the color load that hindered light penetration, making direct application of the dual process (photocatalysis and photo-Fenton) impractical for the UASB and I/L streams. This pretreatment step was necessary to address persistent organics like phenols and lignin derivatives, which were not effectively removed in the initial stage, allowing for enhanced