This study focused on investigating the effect of combined chemical and hydrothermal pretreatment (HTP) on the anaerobic digestibility of thickened waste activated sludge (TWAS). Three different combined pretreatment conditions of HTP + free nitrous acid (FNA), HTP + Acid, and HTP + Alkaline were applied to TWAS. To control and compare the effect of combined pretreatments and a single pretreatment, Acid, Alkaline, FNA and HTP pretreatments were applied done prior to AD. The results of this study revealed that combined pretreatments have higher potential to improve methane production yield and rate but not in the solubilization of COD. The highest methane yield of 275 mL CH₄/g TCOD _added was achieved for the combined pretreatment with FNA and HTP. HTP + FNA pretreatment was found to produce higher methane yields compared to the combination of other typical acid and alkaline reagents with hydrothermal pretreatment. Methane yields of 594, 527, and 544 L CH₄/g VSS added, were achieved for HTP + FNA, HTP + ALK, and HTP + ACID pretreatments, respectively. The preliminary economic analysis showed that out of the combined pretreatment, only combining HTP with FNA is economically feasible.

本研究的重点是研究化学和水热联合预处理 (HTP) 对浓缩废活性污泥 (TWAS) 厌氧消化率的影响。HTP + 游离亚硝酸 (FNA)、HTP + 酸和 HTP + 碱性三种不同的组合预处理条件应用于 TWAS。为了控制和比较组合预处理和单一预处理的效果，在 AD 之前进行酸、碱、FNA 和 HTP 预处理。这项研究的结果表明，联合预处理在提高甲烷产率和产率方面具有更高的潜力，但在 COD 的增溶方面没有潜力。最高甲烷产率 275 mL CH ₄ /g TCOD_添加FNA 和 HTP 的联合预处理实现了。与其他典型的酸性和碱性试剂与水热预处理的组合相比，HTP + FNA 预处理被发现产生更高的甲烷产率。HTP + FNA、HTP + ALK 和 HTP + ACID 预处理分别实现了 594、527和 544 L CH ₄ /g VSS 的甲烷产率。初步经济分析表明，在联合预处理中，只有将 HTP 与 FNA 结合在经济上是可行的。