Abstract: Hydrothermal liquefaction (HTL) can directly convert high water content biomass into bio-oil, which can realize both the harmless treatment and resource utilization of the feedstock. However, the bio-oil property varies from one material to another. In this work, HTL of Chlorella, paper mill sludge, and pharmaceutical sludge under the same reaction condition was performed, and the yield and properties of the bio-oil obtained from these three feedstocks were compared. From the point of view of the raw materials, Chlorella, paper mill sludge, and pharmaceutical sludge had similar carbohydrate content (35wt%~40wt%), Chlorella had a higher protein content but a much lower ash content than the two sludges. After HTL, the bio-oil yields of Chlorella, paper mill sludge, and pharmaceutical sludge were 31.2%, 15.4%, and 19.3%, respectively, the difference in the bio-oil yield was mainly attributed to the difference of the feedstock composition. In addition, Chlorella bio-oil had the highest carbon content and heating value, followed by paper mill sludge bio-oil, and pharmaceutical sludge bio-oil had the lowest carbon content and heating value. The paper mill sludge bio-oil had the highest energy recovery (53.4%), greater than those from Chlorella bio-oil and pharmaceutical sludge bio-oil. The composition of bio-oil was very complex, including hydrocarbons, chain amides, nitrogen-containing heterocyclic compounds, acids, and other compounds. The peak area percentages of hydrocarbon compounds in Chlorella, paper mill sludge, and pharmaceutical sludge bio-oil were 27.3wt%, 16.7wt%, and 28.9wt%, respectively. The peak area percentage of nitrogen-containing heterocyclic compounds in the paper mill sludge bio-oil was the highest (45.1wt%), and the peak area percentage of acids in the Chlorella bio-oil was the maximum (22.2wt%). Besides, the peak area percentage of chain amides present in the bio-oil followed the trends Chlorella bio-oil>pharmaceutical sludge bio-oil>paper mill sludge bio-oil. Furthermore, the maximum weight loss rate of the bio-oils from two sludges was 220~230℃, lower than that of the Chlorella bio-oil (250℃). The low boiling point (<200℃) compound content in paper mill sludge and pharmaceutical sludge bio-oil (~33wt%) was higher than that in Chlorella bio-oil (23wt%). And the fractions below 400℃ in the three kinds of bio-oils were all above 80%. The results of this study indicate that HTL can realize the resource utilization of algae and sludge.

Key words: Biomass, Algae, Sludge, Hydrothermal, Liquefaction, Bio-oil

摘要： 水热液化(HTL)技术可将高含水生物质直接转化为生物油。本工作以小球藻、造纸污泥和制药污泥为原料，对比了三种原料水热液化生物油的特性。结果表明小球藻、造纸污泥和制药污泥的生物油产率分别为31.2%, 15.4%和19.3%。小球藻生物油碳氢含量及热值最高，制药污泥生物油碳氢含量及热值最低，造纸污泥生物油碳氢含量及热值介于两者之间，而造纸污泥生物油能量回收率最高。生物油组成复杂，成分中含有烃类、酸类、链状酰胺和含氮杂环等化合物，制药污泥生物油中烃类化合物的含量最高，为28.9wt%，造纸污泥生物油中含氮杂环化合物最多，为45.1wt%。另外，造纸污泥和制药污泥生物油中低沸点(<200℃)化合物含量为33wt%左右，明显高于小球藻生物油中的低沸点化合物含量(23wt%)。本研究结果表明水热液化可以实现藻类和污泥的资源化利用。

关键词: 生物质, 藻类, 污泥, 水热, 液化, 生物油