School of Engineering, University of British Columbia, Okanagan Campus, 1137 Alumni Ave., Kelowna, BC V1V 1V7, Canada.
Water Res. 2013 Sep 15;47(14):5040-51. doi: 10.1016/j.watres.2013.05.055. Epub 2013 Jun 7.
Microwave (2.45 GHz, 1200 W) and conventional heating (custom pressure vessel) pretreatments were applied to dewatered municipal waste sludge (18% total solids) using identical heating profiles that span a wide range of temperatures (80-160 °C). Fourteen lab-scale semi-continuous digesters were set up to optimize the energy (methane) output and sludge retention time (SRT) requirements of untreated (control) and thermally pretreated anaerobic digesters operated under mesophilic and thermophilic temperatures. Both pretreatment methods indicated that in the pretreatment range of 80-160 °C, temperature was a statistically significant factor (p-value < 0.05) for increasing solubilization of chemical oxygen demand and biopolymers (proteins, sugars, humic acids) of the waste sludge. However, the type of pretreatment method, i.e. microwave versus conventional heating, had no statistically significant effect (p-value >0.05) on sludge solubilization. With the exception of the control digesters at a 5-d SRT, all control and pretreated digesters achieved steady state at all three SRTs, corresponding to volumetric organic loading rates of 1.74-6.96 g chemical oxygen demand/L/d. At an SRT of 5 d, both mesophilic and thermophilic controls stopped producing biogas after 20 d of operation with total volatile fatty acids concentrations exceeding 1818 mg/L at pH <5.64 for mesophilic and 2853 mg/L at pH <7.02 for thermophilic controls, while the pretreated digesters continued producing biogas. Furthermore, relative (to control) organic removal efficiencies dramatically increased as SRT was shortened from 20 to 10 and then 5 d, indicating that the control digesters were challenged as the organic loading rate was increased. Energy analysis showed that, at an elevated temperature of 160 °C, the amount of methane recovered was not enough to compensate for the energy input. Among the digesters with positive net energy productions, control and pretreated digesters at 80 °C were more favorable at an SRT of 10 d.
微波（2.45GHz，1200W）和常规加热（定制压力釜）预处理应用于脱水城市污水污泥（总固体 18%），使用跨越广泛温度范围（80-160°C）的相同加热曲线。建立了 14 个实验室规模的半连续消化器，以优化未经处理（对照）和在中温和高温下运行的热预处理厌氧消化器的能量（甲烷）产量和污泥停留时间（SRT）要求。两种预处理方法均表明，在 80-160°C 的预处理范围内，温度是增加污水污泥化学需氧量和生物聚合物（蛋白质、糖、腐殖酸）溶解的统计学上显著因素（p 值<0.05）。然而，预处理方法的类型，即微波与常规加热，对污泥溶解没有统计学上的显著影响（p 值>0.05）。除了 SRT 为 5d 的对照消化器外，所有对照和预处理消化器在所有三个 SRT 下均达到稳定状态，对应于体积有机负荷率为 1.74-6.96g 化学需氧量/L/d。在 SRT 为 5d 时，中温和高温对照在运行 20d 后停止产生沼气，总挥发性脂肪酸浓度分别超过 1818mg/L（pH<5.64）和 2853mg/L（pH<7.02），而预处理消化器继续产生沼气。此外，随着 SRT 从 20 缩短到 10 再缩短到 5d，相对于对照，有机去除效率显著增加，表明随着有机负荷率的增加，对照消化器受到了挑战。能量分析表明，在 160°C 的高温下，回收的甲烷量不足以补偿能量输入。在具有正净能量产生的消化器中，在 SRT 为 10d 时，80°C 下的对照和预处理消化器更有利。
