污泥自热高温好氧消化效能的化学强化及其机理研究

Autothermal thermophilic aerobic digestion (ATAD) is a promising technology for sewage sludge stabilization. In comparison to anaerobic digestion, efficiency of ATAD process for sludge treatment is doubled while the energy consumption remains similar. According to our previous studies on the characteristic changes of free ammonia, volatile fatty acids (VFA), heavy metals and other inhibitory substances during a typical ATAD process, microbial activities were inhibited within a conventional ATAD system. Hence, the potential is still substantial to improve the efficiency of an ATAD process. Our previous studies have demonstrated that dosing the system with additives such as nitrate, phosphate buffered saline(PBS) can significantly enhance the performance of ATAD. However, how the performance is enhanced via such an intensified process has been an enigma in many aspects. For instance, how can additives affect the inhibitory substance and microbial populations? How did those additives contribute to the nitrogen removal? Do we need to moderately adjust the operation parameters of an ATAD system supplemented with those additives? How to add those combined reagents when different sludge are treated in ATAD system? Moreover, we need to elucidate how sludge stabilization can still be achieved quickly with ORP < 0 mv? Solving the above questions will decipher the key microbial metabolisms and putative mechanisms. This research will investigate those aspects. The obtained results will elucidate the fundamental principles and establish models for sludge degradation. As such, this research will provide a road map for highly efficient sludge stabilization via ATAD process to enhance its practical application.

污泥自热高温好氧消化（ATAD）是一项单位污泥处理能耗接近厌氧消化但反应效率倍增的污泥快速稳定化技术。然而，从消化体系中游离氨氮、挥发性脂肪酸、重金属等抑制微生物活性物质（IMS）的产生与变化规律看，ATAD体系效能的发挥尚有较大的提升空间。本申请团队在前期研究中发现，适时、适量地投硝酸盐、磷酸盐缓冲溶液等组合药剂能大幅提高ATAD体系的污泥稳定化速率，但，该技术尚有诸多机理问题急待探明：硝酸盐、磷酸盐缓冲溶液等组合药剂与IMS各组分间存在怎样的关系？组合药剂添加后，污泥组分和微生物种属发生了怎样的变化？污泥稳定化过程中药剂如何使用？为何投加药剂后体系中总氮反而出现了下降？在体系ORP低于0mv时，污泥消化何以还能快速进行？本申请拟通过这些问题的研究，阐明有关的机理性问题，建立相关的污泥消化反应动力学模型，从而为新技术的推广与应用提供深层次的理论问题。

本课题针对污泥自热高温好氧消化（ATAD）体系特有的有机物代谢环境特点和游离氨氮、挥发性脂肪酸等具有微生物抑制作用的产物的变化规律，提出了以硝酸盐、磷酸缓冲溶液等组合药剂解除产物抑制从而大幅提高污泥稳定化速率的新技术。考察了药剂投加量、投加时段、作用环境参数（消化温度、曝气作用、进料浓度、进料类型、作用环境pH）对ATAD效果的影响，阐明了药剂作用机理。主要研究结果如下：.1、消化结束时硝酸铁强化组较空白组可使挥发性脂肪酸的浓度从5499 mg/L有效降低至716 mg/L，乙酸浓度从2790mg/L 减少至541 mg/L，显著提高了消化过程中微生物的活性。加药组ATP浓度可高达3850 RLU，而空白组中ATP浓度最高只有1455 RLU，使得强化组污泥稳定化的时间较空白组提前了9天，加药组最终VS去除率达到46.36%，而空白组最终VS去除率仅有38.36%。.2、硝酸铁强化污泥ATAD的最佳药剂投加参数为：药剂投加量为以去除1000 mg/L乙酸当量，投加时段为第6天，投加pH为6.5。.3、硝酸铁强化污泥ATAD工艺的最佳作用环境参数为：消化温度为55 ℃，曝气速率为每小时气液比1.0，进料污泥TS浓度为5.5%，进料污泥类型为100%二沉池污泥。.4、硝酸铁投加后不仅降低了VFA的浓度，也改变了VFA的种类分布，有利于微生物降解。酸抑制解除使得ATAD系统内革兰氏阳性菌尤其是Firmicutes的相对丰度明显增加。微生物多样性显著降低，微生物群落结构得到选择性简化和强化作用，从而可溶性有机物中可生化降解部分比例呈倍数增长，显著提高了VS去除率，缩短了污泥稳定化时间。.5、磷酸盐缓冲液的投加可以提高ATAD中污泥的稳定性。磷酸盐缓冲液的最佳用量为0.01 mol/L，处理组VS去除率最高，达到44.42%，比对照组高6.08%。与对照组相比，处理组的稳定时间提前了9天，达到了最高的稳定水平。