水热预处理对城市污泥和微藻混合厌氧发酵产甲烷的影响

Effect of hydrothermal pretreatment on the anaerobic co-digestion of municipal sludge and microalgae for methane production

为了提高城市污泥和微藻混合厌氧发酵产甲烷率,在80℃和120℃水热预处理15~120 min后,对水溶性有机物的溶出、降解规律及厌氧发酵产甲烷特征进行研究。结果表明,120℃处理120 min,城市污泥和微藻有机物溶出效果最佳,水溶性化学需氧量(COD)、总有机碳(TOC)和总氮(TN)含量显著高于未处理组,城市污泥和微藻水溶性有机物以类色氨酸和类酪氨酸蛋白质为主。水热处理过程中,城市污泥蛋白质发生降解,逐渐转化成类腐殖类物质;微藻类色氨酸蛋白逐渐增加,类酪氨酸蛋白逐渐减少,出现了以类腐殖和类腐殖酸类物质为主的荧光特征峰。水热预处理后的城市污泥和微藻混合厌氧发酵累积甲烷产量达204.04 mL/g VS,比未处理混合组提高了7.25%,比城市污泥单独发酵提高了8.48%。研究表明水热预处理能有效提升城市污泥和微藻混合发酵产甲烷效率,这与水热处理对水溶性有机物溶出及降解转化的促进作用有关。

The given paper intends to trace and examine the effects of the hydrothermal pretreatment on the methane production by the anaerobic co-digestion of the municipal sludge and microalgae so as to solve the problem of its low energy utilization rate. As is known,the municipal sludge and microalgae used to be hydrothermally pretreated at 80 ℃ and 120 ℃ for 15-120 min,whereas the optimal treatment condition has to be determined in accordance with the concentration rate of the chemical oxygen demand( COD),the total organic carbon( TOC) and the total nitrogen( TN) rates in the aqueous solution. What is more,the changing regularity of the water-soluble organic matters has to be analyzed via the 3-D fluorescence spectroscopy. And,then,the biochemical methane potential( BMP) test has to be done through the automatic methane potential test system. The results of our testing indicate that the organic matters in it may have the best dissolution effect when treated in the condition of 120 ℃ for120 min,so that the content rate of the water-soluble COD,TOC and TN should be made much higher than that of the untreated counterparts. And,since the substances,the protein contents like tryptophan and tyrosine,are of the main water-soluble organic compounds in the municipal sludge and microalgae,and,in the process of hydrothermal treatment,the protein contents of such municipal sludge tend to get degraded and gradually transformed into humic substances,the tryptophan content,like protein of the microalgae,tend to increase,but the tyrosine,like protein content,tend to decrease gradually. The accumulated fluorescents,like materials are dominated by the turning-up humic and humic acids. And,hence,through the hydrothermal pretreatment,it would be possible for the cumulative methane of the anaerobic co-digestion of municipal sludge and microalgae to reach 204. 04 m L/g VS,which becomes 7. 25% higher than that of the untreated mixed group and 8. 48% higher than that of the single digested usual municipal sludge. And,so,the results of our testing experiments show that hydrothermal pretreatment is in a position to improve the methane production efficiency of anaerobic co-digestion of the municipal sludge and microalgae effectively and efficiently,which proves to be related to the promotion of the hydrothermal treatment on the dissolution and degradation of the water-soluble organic matters.