利用城市生活污水高效培养微藻的优化研究

发布时间：2018-10-14 11:50

【摘要】：化石能源危机和水体富营养化已日益严重,微藻可以有效去除城市生活污水中的氮磷,同时收获的藻细胞可以提取微藻油脂用于生产生物柴油,部分替代化石能源。本文以小球藻作为研究对象,利用城市生活污水作为培养液,通过控制培养条件如灭菌条件、通气量、初始接种密度等,分析这些环境条件对小球藻生物量和脂肪酸组成的影响,研究其对于污水中氮磷等物质的去除规律,综合考察环境因素对小球藻的生物量和总脂肪酸产量的影响,从而优化利用城市生活污水培养小球藻的培养条件,提高小球藻的生物量和总脂肪酸产量。主要结果如下：(1)小球藻可以在不灭菌处理的生活污水中正常生长,但生长速度较慢,且总脂肪酸产量也比较低；城市生活污水进行灭菌处理有利于小球藻的生长和生物量的累积,其中高温蒸汽灭菌处理组的小球藻生物累积量最高,其生物量为0.2181g/L。通气能够增加藻细胞与城市生活污水中营养物质的接触面积,有利于小球藻藻的生长；与不通气培养相比,在通气条件下,城市生活污水中小球藻的生物量累积量明显增加。当通气量为2 L/min,小球藻生物累积量最高为0.2413g/L。增大接种浓度和添加微量元素都有利于小球藻的生长和生物量的累积。(2)在小球藻细胞中,C16：0(棕桐油)、C18：1(油酸)、C18：2(亚油酸)和C18：3(亚麻酸)含量较高。环境条件对小球藻的脂肪酸组成具有一定的影响。灭菌条件越严格,有利于藻细胞对不饱和脂肪酸,特别是多不饱和脂肪酸的累积,高温蒸汽灭菌的藻细胞中不饱和脂肪酸和多不饱和脂肪酸含量最高,分别占脂肪酸总量的62.68%和25.74%。通气条件下的藻细胞中不饱和脂肪酸的含量要高于不通气条件。通气量为1 L/min时,藻细胞中不饱和脂肪酸和多不饱和脂肪酸的含量最多。但随着通气量的增加,藻细胞中饱和脂肪酸含量上升,不饱和脂肪酸和多不饱和脂肪酸含量下降。接种浓度增加时,藻细胞中饱和脂肪酸的含量呈上升趋势,不饱和脂肪酸和多不饱和脂肪酸的含量则有下降的趋势。添加微量元素后,藻细胞中脂肪酸的种类较为丰富,但是饱和脂肪酸、不饱和脂肪酸和多不饱和脂肪酸的含量会下降。(3)小球藻对城市生活污水有着良好的净化效果。灭菌处理、增加通气量、加大接种浓度和添加微量元素能够提高小球藻对COD、NH4+-N、TN、TP的净化效率。小球藻对COD的净化基本都是在72h内完成,对COD的净化率都可以达到55%以上。污水中TN和NH4+-N的去除贯穿了整个培养过程,TN和NH4+-N含量随着培养时间的增加而下降,最终TN和NH4+-N的含量稳定在一定的水平上。对TN和NH4+-N的去除基本是在72h内完成,且最终对TN和NH4+-N的去除率都高达83.6%和80%以上。小球藻对TP的净化总体呈现为先迅速下降,再有所回升,并稳定。在接种后24h内,小球藻对TP的去除速度最快,污水中TP的含量呈直线下降的趋势,此时,去除率达到最大值,各组的TP去除率均可达到73%以上,但之后污水中TP的含量有所回升并处于上下波动的状态,最终基本稳定在一定的水平,最终对T.P的去除率也可达到47.5%以上。(4)对小球藻的培养条件进行多因子优化研究,确定了小球藻的最佳培养条件：通气量为2 L/min,接种浓度为2.1×106个/ml,不添加微量元素,总脂肪酸量理论值为42ug/mg,实际测定值为37.8ug/mg,相对误差为10%。
[Abstract]:The fossil energy crisis and the eutrophication of water bodies are becoming more and more serious. Microalgae can effectively remove the nitrogen and phosphorus in urban domestic sewage, and the harvested algae cells can extract micro algae oil for the production of biodiesel and partly replace fossil energy. The effects of these environmental conditions on biomass and fatty acid composition of chlorella were analyzed by controlling culture conditions such as sterilization condition, aeration quantity, initial inoculation density and so on. The effects of environmental factors on the biomass of chlorella and the total fatty acid yield of chlorella were investigated, and the biomass and total fatty acid yield of chlorella were improved. The main results are as follows: (1) the chlorella can grow normally in the domestic sewage without sterilization treatment, but the growth speed is slow, and the total fatty acid yield is low; the sterilization treatment of urban domestic sewage is beneficial to the growth of chlorella and the accumulation of biomass, The biomass of chlorella in the high-temperature steam sterilization treatment group was 0. 2181g/ L. The aeration can increase the contact area between the algae cells and the nutrients in urban domestic sewage, which is beneficial to the growth of chlorella; compared with the non-aeration culture, the biomass accumulation amount of chlorella in urban domestic sewage is obviously increased under the condition of aeration. When the ventilation volume was 2L/ min, the bioaccumulation amount of chlorella was 0.2413g/ L. Increasing the inoculation concentration and adding trace elements are beneficial to the growth of chlorella and the accumulation of biomass. (2) In chlorella cells, C16: 0 (brown color), C18: 1 (oleic acid), C18: 2 (linoleic acid) and C18: 3 (linolenic acid) were high in content. Environmental conditions have a certain effect on the fatty acid composition of chlorella. The more stringent the sterilization conditions, it is beneficial to the accumulation of unsaturated fatty acids, especially polyunsaturated fatty acids, in algae cells. The content of unsaturated fatty acids and polyunsaturated fatty acids in algae cells sterilized by high temperature steam accounts for 62. 68% and 25.74% of the total fatty acids. The content of unsaturated fatty acids in algal cells under ventilation should be higher than that of non-aeration. When the ventilation volume is 1 L/ min, the content of unsaturated fatty acid and polyunsaturated fatty acid in algae cells is most abundant. However, with the increase of ventilatory capacity, the content of saturated fatty acids in algae cells increased, and the content of unsaturated fatty acids and polyunsaturated fatty acids decreased. When the inoculation concentration increased, the content of saturated fatty acids in algae cells was increasing, and the content of unsaturated fatty acids and polyunsaturated fatty acids decreased. The content of saturated fatty acid, unsaturated fatty acid and polyunsaturated fatty acid will decrease after adding trace elements. (3) The chlorella has good purifying effect on urban domestic sewage. Sterilization treatment, increased aeration, increased inoculation concentration and addition of trace elements could improve the purification efficiency of chlorella on COD, NH4 +-N, TN and TP. The purification of COD in chlorella is basically completed within 72h, and the purification rate of COD can reach above 55%. The removal of TN and NH4 +-N in sewage runs through the whole culture process, and the content of TN and NH4 +-N decreases with the increase of culture time, and the content of TN and NH4 +-N is stable at a certain level. The removal of TN and NH4 +-N was basically completed within 72h, and the removal rate of TN and NH4 +-N was 83.6% and more than 80%. The purification of TP in chlorella was first decreased rapidly, and then recovered and stabilized. Within 24h after inoculation, the removal rate of TP was the fastest, and the content of TP in sewage decreased linearly. At this time, the removal rate reached the maximum, the TP removal rate of each group could reach more than 73%, but the TP content in sewage recovered and was in the state of upper and lower fluctuation. In the end, the removal rate of T. P can reach 47. 5%. (4) A multi-factor optimization study was carried out on the cultivation conditions of chlorella, and the optimal culture conditions of chlorella were determined: the ventilation volume was 2 L/ min, the inoculation concentration was 2. 1/ 106/ ml, the trace elements were not added, the theoretical value of total fatty acid was 42ug/ mg, the actual measured value was 37. 8ug/ mg, and the relative error was 10%.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X799.3

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