Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia.
JP CCN Domžale-Kamnik d.o.o., Domžale-Kamnik WWTP, Domžale, Slovenia.
J Environ Manage. 2023 Dec 1;347:119074. doi: 10.1016/j.jenvman.2023.119074. Epub 2023 Oct 5.
Anaerobic digestion in wastewater treatment plants converts its unwanted end product - waste activated sludge into biogas. Even if the process is well established, pre-treatment of the sludge can further improve its efficiency. In this study, four treatment regimes for increasing methane production through prior sludge disintegration were investigated using lab-scale cavitation generator and real sludge samples. Three different cavitating (attached cavitation regime, developed cloud shedding cavitation regime and cavitation in a wake regime) and one non-cavitating regime at elevated static pressure were studied in detail for their effectiveness on physical and chemical properties of sludge samples. Volume-weighted mean diameter D[4,3] of sludge's particles decreased by up to 92%, specific surface area increased by up to 611%, while viscosity (at a shear rate of 3.0 s) increased by up to 39% in the non-cavitating and decreased by up to 24% in all three cavitating regimes. Chemical changes were more pronounced in cavitating regimes, where released soluble chemical oxygen demand (sCOD) and increase of dissolved organic matter (DOM) compounds by up to 175% and 122% were achieved, respectively. Methane production increased in all four cases, with the highest increase of 70% corresponding to 312 mL CH g COD. However, this treatment was not particularly efficient in terms of energy consumption. The best energy balance was found for the regime with a biochemical methane potencial increase of 43%.
污水处理厂中的厌氧消化将其不需要的最终产物——废活性污泥转化为沼气。即使该过程已经得到很好的确立，对污泥进行预处理也可以进一步提高其效率。在这项研究中，使用实验室规模的空化发生器和实际的污泥样品，通过预先的污泥解体来提高甲烷产量，研究了四种处理方案。详细研究了三种不同的空化（附着空化、发展的云脱落空化和尾流空化）和一种在升高的静压下的非空化条件，以研究它们对污泥样品的物理和化学性质的有效性。污泥颗粒的体积加权平均直径 D[4,3]降低了多达 92%，比表面积增加了多达 611%，而在非空化条件下，粘度（剪切速率为 3.0 s）增加了多达 39%，而在所有三种空化条件下降低了多达 24%。在空化条件下，化学变化更为明显，其中释放的可溶性化学需氧量（sCOD）和溶解有机物（DOM）化合物的增加分别达到了 175%和 122%。在所有四种情况下，甲烷产量都有所增加，最高增加了 70%，对应于 312 mL CH g COD。然而，就能源消耗而言，这种处理方式并不是特别有效。在生化甲烷潜能增加 43%的情况下，发现了最佳的能量平衡。
