CIEPQPF - Centre of Chemical Processes Engineering and Forest Products, Department of Chemical Engineering, University of Coimbra, Rua Silvio Lima, 3030-790, Coimbra, Portugal; IFB - Federal Institute of Education, Science, and Technology of Brasília - IFB, Campus Ceilândia Brasília - Federal District, Brazil.
CIEPQPF - Centre of Chemical Processes Engineering and Forest Products, Department of Chemical Engineering, University of Coimbra, Rua Silvio Lima, 3030-790, Coimbra, Portugal.
J Environ Manage. 2020 May 1;261:109944. doi: 10.1016/j.jenvman.2019.109944. Epub 2020 Mar 2.
This study aims to investigate the sewage sludge (SS) drying process by incorporating a by-product formed in the pulp and paper industry (green liquor dregs - GLD) as drying adjuvant. Through an innovative approach, the drying kinetics was modelled, and the final dried product was tested for soil applications. After the characterization phase, small cylinders of SS without and with 0.15 g GLD g SS (SS_GLD) were dried in isothermal conditions at 70, 100, and 130 °C. The experimental data were fitted by Fick's second law and thin-layer models, and good results were achieved in both cases (R > 0.98 and RMSE <0.05). Although only a slight improvement was observed, the best conditions for drying biosolids were found with the addition of GLD at 130 °C, where the drying rate was 30.88 gHO kg SS min. In this condition, a decrease of 8% in the energy required for moisture evaporation was observed. Regarding the phytotoxicity tests with Lepidium sativum L. (garden cress), 60% improvement in EC was noticed for the sample with GLD when compared to the raw SS. The dried product SS_GLD complied with the regulations for soil applications regarding the potentially toxic metals (Cr, Ni, Cu, Pb, Zn, and Cd), and promoted an increase in soil organic matter and pH. However, further and in-depth studies should be conducted to assess the potential of SS_GLD application in agricultural soil.
本研究旨在探讨将制浆造纸工业副产物（绿液渣-GLD）纳入污泥（SS）干燥过程中作为干燥助剂的方法。通过创新方法，对干燥动力学进行了建模，并对最终的干燥产品进行了土壤应用测试。在特征描述阶段之后，将没有和含有 0.15 g GLD g SS（SS_GLD）的 SS 小圆柱体在 70、100 和 130°C 的恒温条件下进行干燥。通过菲克第二定律和薄膜模型对实验数据进行拟合，两种情况下都得到了良好的结果（R>0.98 和 RMSE<0.05）。尽管观察到仅略有改善，但在添加 GLD 时在 130°C 下发现了最适合干燥生物固体的条件，此时干燥速率为 30.88 gHO kg SS min。在这种条件下，观察到蒸发水分所需的能量减少了 8%。关于用蕹菜（蕹菜）进行的植物毒性测试，与原始 SS 相比，含有 GLD 的样品的 EC 值提高了 60%。干燥产品 SS_GLD 符合土壤应用中关于潜在有毒金属（Cr、Ni、Cu、Pb、Zn 和 Cd）的规定，并促进了土壤有机质和 pH 值的增加。然而，应该进行进一步和深入的研究，以评估 SS_GLD 在农业土壤中的应用潜力。
