PAPER making! g! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 11, Number 3, 2025
affecting these absorption mechanisms were identified through a series of experiments and principal component analysis (PCA). The results showed that the water absorption capacity, driven by capillary action (porosity), exhibited differences between two-dimensional surface absorption (in the X and Y directions) and three-dimensional bulk absorption (including the Z direction, or thickness). Porosity analysis revealed that three-dimensional absorbency is highly correlated with porosity, whereas two-dimensional absorbency has a relatively low correlation and is influenced by fiber properties such as length and width, as well as mass- related characteristics including fines content and freeness. The findings highlight the need to balance these dimensional properties to achieve optimal absorbency in paper towel products. Additionally, this study provides a foundation for developing more efficient paper towels and offers valuable insights into the complex mechanisms of paper towel absorbency, which will aid in the development of improved hygiene paper products. WASTE TREATMENT “The treatment of papermaking effluent with the hybrid process of coagulation- ozonation-membrane filtration in order to recycle and reuse”, Mahdi Elyasi Kojabad & Ali Aghdami, Iranian Journal of Health and Environment , 18(2), (9-2025), 335-348. Background and Objective : The paper industry is one of the most water-intensive sectors, generating a large volume of wastewater. Proper management of this waste—including its treatment, recycling, and reuse—can help prevent environmental pollution and conserve the country's water resources. In this study, a three-step process consisting of coagulation, ozonation, and membrane filtration was employed to treat papermaking wastewater. Materials and Methods : A three-step process involving coagulation, ozonation, and membrane filtration was employed to treat the wastewater. In the first stage, polyaluminum chloride (PAC) was used to remove larger particles. This was followed by ozonation to degrade complex organic compounds. The final stage involved membrane filtration to further purify the water. At each stage, the chemical oxygen demand (COD) of the wastewater was measured and analyzed for comparative evaluation. Results : Each stage played a critical role in the treatment process. Coagulation effectively removed a substantial amount of suspended particles, while ozonation addressed issues related to color and the breakdown of complex compounds. The final stage, membrane filtration, was instrumental in eliminating extremely fine suspended particles. Despite these efforts, the treated effluent exhibited a higher COD than the initial sample, possibly due to the release of intermediate compounds during treatment. However, the process successfully reduced the concentration of crude oil by 66%. Conclusion : The membrane flux analysis revealed that at pH levels of 11 and 14, the effluent’s membrane flux closely approached that of pure water. This finding highlights the potential effectiveness of the proposed purification method for the treatment and recycling of papermaking wastewater. “CaCO 3 accumulation in the wastewater treatment system of a recycled paper mill with zero-liquid discharge”, Qingsi Song, Qiang Ge, Xianbo Zhou, Yujia Wang, Guifang Liu, Hefang Liu, Congyun Zhu, Kuanyong Liu & Shucheng Yang, Water Environment Research , 97(6), June 2025, e70094. The accumulation of CaCO 3 caused by wastewater recycling is a common problem in recycled paper mills. This study analyzed the process water, wastewater and sludge characteristics of a zero-liquid-discharge recycled paper mill to explore the sources of calcium and the impacts of CaCO 3 precipitation. The results showed that the primary factor responsible for CaCO 3 dissolution during water closed recirculating was the pH reduction resulting from volatile fatty acids (VFA) generated through organic matter hydrolysis and acidification. VFAs, functioning as weak organic acids, participate in neutralization reactions with CaCO 3 , thereby enhancing its dissolution. Each ton of wastepaper could introduce about 5kg calcium into wastewater. Ca 2+ was mainly
Technical Abstracts
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