University of Verona, Department of Biotechnology, Strada Le Grazie, 15, 37134 Verona, Italy.
Waste Manag. 2012 Jun;32(6):1196-201. doi: 10.1016/j.wasman.2012.01.006. Epub 2012 Feb 4.
The paper reports the findings of a two-year pilot scale experimental trial for the mesophilic (35°C), thermophilic (55°C) and temperature phased (65+55°C) anaerobic digestion of waste activated sludge. During the mesophilic and thermophilic runs, the reactor operated at an organic loading rate of 2.2 kgVS/m(3)d and a hydraulic retention time of 20 days. In the temperature phased run, the first reactor operated at an organic loading rate of 15 kgVS/m(3)d and a hydraulic retention time of 2 days while the second reactor operated at an organic loading rate of 2.2 kgVS/m(3)d and a hydraulic retention time of 18 days (20 days for the whole temperature phased system). The performance of the reactor improved with increases in temperature. The COD removal increased from 35% in mesophilic conditions, to 45% in thermophilic conditions, and 55% in the two stage temperature phased system. As a consequence, the specific biogas production increased from 0.33 to 0.45 and to 0.49 m(3)/kgVS(fed) at 35, 55, and 65+55°C, respectively. The extreme thermophilic reactor working at 65°C showed a high hydrolytic capability and a specific yield of 0.33 g COD (soluble) per gVS(fed). The effluent of the extreme thermophilic reactor showed an average concentration of soluble COD and volatile fatty acids of 20 and 9 g/l, respectively. Acetic and propionic acids were the main compounds found in the acids mixture. Because of the improved digestion efficiency, organic nitrogen and phosphorus were solubilised in the bulk. Their concentration, however, did not increase as expected because of the formation of salts of hydroxyapatite and struvite inside the reactor.
本文报道了为期两年的中温（35°C）、高温（55°C）和温度分相（65+55°C）厌氧消化剩余活性污泥的中试试验结果。在中温和高温运行期间，反应器的有机负荷率为 2.2kgVS/m³·d，水力停留时间为 20 天。在温度分相运行期间，第一反应器的有机负荷率为 15kgVS/m³·d，水力停留时间为 2 天，而第二反应器的有机负荷率为 2.2kgVS/m³·d，水力停留时间为 18 天（整个温度分相系统为 20 天）。随着温度的升高，反应器的性能得到改善。COD 去除率从中温条件下的 35%提高到高温条件下的 45%，再提高到两段温度分相系统下的 55%。因此，比沼气产量从 35°C 时的 0.33m³/kgVS（进料）分别增加到 55°C 时的 0.45m³/kgVS（进料）和 65+55°C 时的 0.49m³/kgVS（进料）。在 65°C 下运行的极端高温反应器表现出很高的水解能力和 0.33gCOD（可溶）/gVS（进料）的比产率。极端高温反应器的出水显示出平均浓度为 20g/l 的可溶性 COD 和 9g/l 的挥发性脂肪酸。乙酸和丙酸是酸混合物中发现的主要化合物。由于消化效率的提高，有机氮和磷在主体中溶解。然而，由于在反应器内形成了羟基磷灰石和鸟粪石的盐，它们的浓度并没有像预期的那样增加。
