Microalgal biomass grown in wastewater treatment raceway ponds may be valorised producing bioenergy through anaerobic digestion. However, pretreatment techniques seem to be necessary for enhancing microalgae methane yield. In this study, hydrothermal pretreatment was studied prior to batch and continuous reactors. The pretreatment increased organic matter solubilisation (8-13%), anaerobic digestion rate (30-90%) and final methane yield (17-39%) in batch tests. The highest increase was attained with the pretreatment at 130 degrees C for 15 min, which was attested in a laboratory-scale continuous reactor operated at a hydraulic retention time of 20 days with an average organic loading rate of 0.7 g VS/L center dot day. The methane yield increased from 0.12 to 0.17 L CH4/g VS (41%) in the pretreated digester as compared to the control. Microscopic images of microalgal biomass showed that pretreated cells had unstructured organelles and disrupted cell wall external layer, which may enhance the hydrolysis. Indeed, images of the pretreated reactor digestate showed how cells were more degraded than in the control reactor. (C) 2014 Elsevier Ltd. All rights reserved.
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机译：废水处理跑道池中生长的微藻生物质可以通过厌氧消化进行增值生产生物能源。然而，预处理技术似乎对于提高微藻甲烷的产率是必需的。在这项研究中，对间歇式和连续式反应器进行水热预处理进行了研究。在分批测试中，预处理提高了有机物的溶解度（8-13％），厌氧消化率（30-90％）和最终甲烷产率（17-39％）。在130℃预处理15分钟可获得最高的增加，这是在实验室规模的连续反应器中进行的，该反应器在20天的水力停留时间下运行，平均有机负载率为0.7 g VS / L中心点日。与对照相比，预处理蒸煮器中的甲烷产率从0.12 L CH4 / g VS增加至0.17 L CH4 / g VS（41％）。显微藻类生物量的显微图像显示，预处理的细胞具有无结构的细胞器和破坏的细胞壁外层，这可能会增强水解作用。实际上，经过预处理的反应器消化物的图像显示出与对照反应器相比，细胞如何降解得更多。 （C）2014 Elsevier Ltd.保留所有权利。
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