State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Water Res. 2022 Jul 15;220:118657. doi: 10.1016/j.watres.2022.118657. Epub 2022 May 25.
The prolonged reaction period and low methane yield have become a pivotal bottleneck in the anaerobic digestion (AD) of waste activated sludge (WAS), severely limiting its use in bioenergy. This study evaluated the long-term semi-continuous AD of WAS with isoelectric-point (pI) pretreatment in terms of the reaction period, methane yield, material resource recovery, and economic and environmental benefits. The experimental results show that after pI pretreatment, at the same solids retention time (SRT), the average methane yield and methane content in the biogas of WAS increased by 120.9% and 15.5%, respectively. The average methane yield from AD with pI pretreatment at a 5-day SRT was 1.6 times that of the AD without pI pretreatment at a 15-day SRT, indicating that pI pretreatment significantly (P < 0.001) increased the methane yield from the AD of WAS at different SRTs, even at an ultra-short SRT. Statistical analyses of the changes in the concentrations of soluble organic matter in the AD process with and without pI pretreatment confirmed that pI pretreatment enhanced the biochemical reactions related to the transformation of sludge organic matter during the whole AD process, but not the initial organic solubilisation and hydrolysis of the sludge. Furthermore, pI pretreatment recovered the NaHCO, NaS, and multivalent metals from the sludge, indicating that AD with pI pretreatment efficiently recovered both bioenergy and material resources from the sludge. Economic and environmental analyses of AD with and without pI pretreatment further indicated that with pI pretreatment, the annual economic benefit of AD increases by 162% and carbon emissions decreases by approximately 2.63 × 10 kg CO/year compared with conventional AD. These findings serve as an important reference for the development of a novel AD technology for sludge that incorporates second-generation pretreatment and operates at an ultra-short SRT.
该研究采用等电点（pI）预处理方法，从反应周期、甲烷产量、物质资源回收和经济环境效益等方面评估了长期半连续厌氧消化（AD）废活性污泥（WAS）的性能。实验结果表明，pI 预处理后，在相同的固体停留时间（SRT）下，WAS 沼气中的平均甲烷产量和甲烷含量分别提高了 120.9%和 15.5%。pI 预处理在 5 天 SRT 下的平均甲烷产量是无 pI 预处理在 15 天 SRT 下的 1.6 倍，这表明 pI 预处理显著（P<0.001）提高了不同 SRT 下 WAS 的 AD 甲烷产量，甚至在超短 SRT 下也是如此。有无 pI 预处理的 AD 过程中可溶性有机物浓度变化的统计分析证实，pI 预处理增强了与污泥有机物转化相关的生化反应，而不是污泥的初始有机溶解和水解。此外，pI 预处理从污泥中回收了 NaHCO3、Na2S 和多价金属，表明 pI 预处理的 AD 有效地从污泥中回收了生物能源和物质资源。有无 pI 预处理的 AD 的经济和环境分析进一步表明，与传统 AD 相比，pI 预处理的 AD 每年的经济效益增加了 162%，碳排放量减少了约 2.63×10kg CO/年。这些发现为开发新型 AD 技术提供了重要参考，该技术将第二代预处理和超短 SRT 结合应用于污泥处理。
