GEMMA-Group of Environmental Engineering and Microbiology, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, c/Jordi Girona 1-3, Building D1, E-08034 Barcelona, Spain.
Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, Universitat de Barcelona, Av. Diagonal 643, 08007 Barcelona, Spain.
Molecules. 2018 Aug 21;23(9):2096. doi: 10.3390/molecules23092096.
This study aims at optimizing the anaerobic digestion (AD) of biomass in microalgal-based wastewater treatment systems. It comprises the co-digestion of microalgae with primary sludge, the thermal pretreatment (75 °C for 10 h) of microalgae and the role of the hydraulic retention time (HRT) in anaerobic digesters. Initially, a batch test comparing different microalgae (untreated and pretreated) and primary sludge proportions showed how the co-digestion improved the AD kinetics. The highest methane yield was observed by adding 75% of primary sludge to pretreated microalgae (339 mL CH₄/g VS). This condition was then investigated in mesophilic lab-scale reactors. The average methane yield was 0.46 L CH₄/g VS, which represented a 2.9-fold increase compared to pretreated microalgae mono-digestion. Conversely, microalgae showed a low methane yield despite the thermal pretreatment (0.16 L CH₄/g VS). Indeed, microscopic analysis confirmed the presence of microalgae species with resistant cell walls (i.e., sp. and diatoms). In order to improve their anaerobic biodegradability, the HRT was increased from 20 to 30 days, which led to a 50% methane yield increase. Overall, microalgae AD was substantially improved by the co-digestion with primary sludge, even without pretreatment, and increasing the HRT enhanced the AD of microalgae with resistant cell walls.
本研究旨在优化基于微藻的废水处理系统中生物质的厌氧消化（AD）。它包括微藻与原污泥的共消化、微藻的热预处理（75°C 10 小时）以及水力停留时间（HRT）在厌氧消化器中的作用。最初，通过比较不同的微藻（未经处理和预处理）和原污泥比例的批处理试验表明，共消化如何改善 AD 动力学。通过向预处理的微藻中添加 75%的原污泥（339 mL CH₄/g VS），观察到最高的甲烷产量。然后在中温实验室规模反应器中研究了该条件。平均甲烷产量为 0.46 L CH₄/g VS，与预处理的微藻单消化相比增加了 2.9 倍。相反，尽管进行了热预处理，微藻的甲烷产量仍然很低（0.16 L CH₄/g VS）。事实上，显微镜分析证实存在具有抗性细胞壁的微藻物种（即 sp. 和硅藻）。为了提高它们的厌氧生物降解性，将 HRT 从 20 天增加到 30 天，导致甲烷产量增加了 50%。总体而言，通过与原污泥共消化，即使没有预处理，微藻的 AD 也得到了极大的改善，并且增加 HRT 可以提高具有抗性细胞壁的微藻的 AD。
