This paper investigated the effect of alkaline hydrothermal pretreatment (HTP) on the hydrolysis, biodegradation and methane generation potential of waste activated sludge (WAS). A multi-variable experimental approach was designed, where initial solids content (1-5%), reaction temperature (130-190 °C), reaction time (10-30 min.) and caustic concentration (0-0.2 mgNaOH/mgVS) were varied in different combinations to assess the impact of alkaline HTP. This process significantly enhanced the hydrolysis of organic compounds in sludge into soluble fractions, whereby increasing the chemical oxygen demand (COD) leakage up to 200-900% with the 17-99% solubility. It boosted volatile solids (VS) biodegradation up to 40%, which resulted in a parallel increase in methane generation from 216 mLCH4/gVS to as high a 456 mLCH4/gVS methane generation basically relied on the conversion of solubilized COD. Alkaline HTP process was optimized for the maximum methane production. Optimum conditions were obtained at 190 °C reaction temperature, 10 min. reaction time, 0.2 mgNaOH/mgVS and 5% dry matter content. Under these conditions, 453.8 mLCH4/gVS was predicted. Biochemical methane potential (BMP) value was determined as 464 mLCH4/gVS supporting predictive power of the BMP model. The biodegradability compared to the untreated raw WAS was enhanced 78.2%.

中文翻译：

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在厌氧条件下优化碱性水热预处理生物污泥以提高甲烷生成量。

本文研究了碱性水热预处理（HTP）对废活性污泥（WAS）的水解，生物降解和甲烷生成潜力的影响。设计了一种多变量实验方法，其中初始固体含量（1-5％），反应温度（130-190°C），反应时间（10-30分钟）和苛性碱浓度（0-0.2 mgNaOH / mgVS）不同的组合以评估碱性HTP的影响。此过程显着增强了污泥中有机化合物水解成可溶级分的能力，从而使化学需氧量（COD）泄漏增加到200-900％，溶解度为17-99％。它使挥发性固体（VS）的生物降解率提高了40％，甲烷的生成量从216 mLCH4 / gVS平行增加到456 mLCH4 / gVS的甲烷生成量基本上依赖于溶解的COD的转化。碱性HTP工艺经过优化，可最大程度地生产甲烷。在190°C反应温度下10分钟获得了最佳条件。反应时间为0.2 mgNaOH / mgVS，干物质含量为5％。在这些条件下，预计会有453.8 mLCH4 / gVS。确定的生化甲烷潜力（BMP）值为464 mLCH4 / gVS，可支持BMP模型的预测能力。与未处理的原始WAS相比，其生物降解性提高了78.2％。2 mgNaOH / mgVS和5％的干物质含量。在这些条件下，预计会有453.8 mLCH4 / gVS。确定的生化甲烷潜力（BMP）值为464 mLCH4 / gVS，可支持BMP模型的预测能力。与未处理的原始WAS相比，其生物降解性提高了78.2％。2 mgNaOH / mgVS和5％的干物质含量。在这些条件下，预计会有453.8 mLCH4 / gVS。确定的生化甲烷潜力（BMP）值为464 mLCH4 / gVS，可支持BMP模型的预测能力。与未处理的原始WAS相比，其生物降解性提高了78.2％。