Doğan Ilgin, Sanin F Dilek
Department of Environmental Engineering, Middle East Technical University, Ankara, Turkey.
Water Res. 2009 May;43(8):2139-48. doi: 10.1016/j.watres.2009.02.023. Epub 2009 Feb 26.
Commonly used pretreatment method of alkaline solubilization (using NaOH) and a relatively new technology of microwave (MW) irradiation (160 degrees C) were combined as a pretreatment method of waste activated sludge (WAS) in this study. First alkaline and MW pretreatment methods were examined separately, then their combination for different conditions was investigated in terms of their effect on COD solubilization, turbidity and capillary suction time (CST). For combined pretreatments, soluble COD to total COD ratio (SCOD/TCOD) of WAS increased from 0.005 (control) to 0.18, 0.27, 0.34 and 0.37 for combined methods of MW and pH-10, 11, 12 and 12.5, respectively. Deteriorated dewaterability due to alkaline pretreatment was also improved due to the incorporation of MW irradiation. Further, with small scale batch anaerobic reactors, pH-10, pH-12, MW (alone), MW+pH-10 and MW+pH-12 pretreated WAS samples were anaerobically digested. Highest total gas and methane productions were achieved with MW+pH-12 pretreatment with 16.3% and 18.9% improvements over control reactor, respectively. Finally the performance of MW+pH-12 pretreatment was examined with 2L anaerobic semi-continuous reactors for 92 days and compared to that of the control reactors. These reactors were operated at an SRT of 15 days. After steady state, 43.5% and 55% improvements were obtained in respective daily total gas and methane productions. TS, VS and TCOD reductions were improved by 24.9%, 35.4% and 30.3%, respectively based on a relative calculation with respect to control reactors. This way combined alkaline-microwave treatment proved to be an effective sludge minimization method. Pretreated digested sludge had 22% improved dewaterability than unpretreated digested sludge. Higher SCOD and NH(3)-N concentrations were measured in the pretreated digested sludge supernatant; however, PO(4)-P concentration did not increase much.
本研究将常用的碱溶预处理方法（使用NaOH）与相对较新的微波（MW）辐照技术（160℃）相结合，作为废弃活性污泥（WAS）的预处理方法。首先分别考察了碱预处理和微波预处理方法，然后研究了它们在不同条件下的组合对化学需氧量（COD）溶解、浊度和毛细吸水时间（CST）的影响。对于联合预处理，WAS的可溶性COD与总COD之比（SCOD/TCOD）从0.005（对照）分别增加到微波与pH值为10、11、12和12.5联合处理方法下的0.18、0.27、0.34和0.37。由于引入了微波辐照，碱预处理导致的脱水性能恶化也得到了改善。此外，使用小型间歇式厌氧反应器，对pH值为10、pH值为12、微波（单独）、微波+pH值为10和微波+pH值为12预处理的WAS样品进行厌氧消化。微波+pH值为12预处理的总气体和甲烷产量最高，分别比对照反应器提高了16.3%和18.9%。最后，使用2L厌氧半连续反应器对微波+pH值为12预处理的性能进行了92天的考察，并与对照反应器进行了比较。这些反应器在污泥停留时间（SRT）为15天的条件下运行。稳态后，每日总气体和甲烷产量分别提高了43.5%和55%。基于与对照反应器的相对计算，总固体（TS）、挥发性固体（VS）和总化学需氧量（TCOD）的减少分别提高了24.9%、35.4%和30.3%。这样，碱-微波联合处理被证明是一种有效的污泥减量化方法。预处理后的消化污泥脱水性能比未预处理的消化污泥提高了22%。预处理后的消化污泥上清液中测得较高的SCOD和氨氮（NH₃-N）浓度；然而，磷酸盐（PO₄-P）浓度没有太大增加。
